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• 2331. [Article] Black truffle economics : evaluating the costs and returns of establishing and producing Tuber melanosporum in the Willamette Valley, Oregon.

  The following paper is an objective view on the viability of growing the truffle Tuber melanosporum in the Willamette Valley. Included in this study are the history of the truffle, biological cycle, habitat ...

  Citation × Citation Citation Abstract Copy Title: Black truffle economics : evaluating the costs and returns of establishing and producing Tuber melanosporum in the Willamette Valley, Oregon. Author: Alvis, Heather E. The following paper is an objective view on the viability of growing the truffle Tuber melanosporum in the Willamette Valley. Included in this study are the history of the truffle, biological cycle, habitat description, method of cultivation and an enterprise budget for commercial production in the Willamette Valley. The truffle, a fungus that grows naturally underground, has long been a delicacy in European culture and it continues to appear in expensive restaurants around the world. The cultivation of T melanosporum was established first in Europe, but is gaining popularity in other parts of the world. Farms are appearing in Israel, Australia, The United States, New Zealand, and other nations. North Carolina and California also have operating truffle farms. Several species are currently cultivated in Europe, but the most prevalent and the only species cultivated outside of Europe is the Perigord (Black) truffle, Tuber melanosporum. Truffles are the fruiting bodies of various fungi. Spores produced within fruiting body germinate into tiny hair-like filaments (mycelia) that eventually attach themselves to the root tips of a host species and form mycorrhiza. After about six years, secondary mycelia emanating from the mycorrhizae grow together into a knot and form the fruiting body or carpophore. Host trees vary according to the location and species of truffle, however oak and hazelnut trees are most commonly used. Host trees that have been mycorrhized with truffles can be purchased from reputable growers for about $15 each. The climatic characteristics of the Willamette Valley are similar to those of major truffle growing regions in Europe. In addition, soils in the Willamette Valley may have an advantage because potentially competitive ectomycorrhizal fungi are adapted to acidic soils. T. melanosporum is grown in soils with high pH. Raising the soil pH for T. melanosporum could reduce the competition from native fungi adapted to acidic soils. Although few attempts have been made to cultivate truffles in Oregon, the Willamette Valley could be an ideal habitat for growing Tuber melanosporum. Establishment of a truffle farm takes 7 to 12 years depending on the species and the condition of the plot. Land must be free of plants that support ectomycorrhizal fungi, have evenly mixed sand, silt and clay (or well drained soils) and have an alkaline pH. An irrigation system should be installed in case of drought. After the trees are planted, maintenance of the truffle plot involves tilling the soil once a year, liming to maintain pH and pruning the host trees. Production typically begins after about six years and full production after about 10 years. Yields are difficult to estimate because truffle production is heavily influenced by weather conditions. In Europe, typical yields range from 50-150 kg per hectare (50-150 pounds per acre) in different plantations. The enterprise budget for a truffle farm in the Willamette Valley considers the costs and returns for a newly established farm. The budget is, by design, only a guide and does not consider individual differences among farmers. For example, it is expected that truffle cultivation will be an enterprise added to an existing farm, however the included budget includes costs of renting machinery for tilling. For a farmer that already owns his/her machinery, the budget must be altered accordingly. Truffles are expensive to produce. Profit and loss depend greatly on yield and price per pound. Also, commercial cultivation of truffles has not been achieved in Oregon and results are unpredictable. In good years, however some farms yield more than 100 kg per hectare (100 pounds per acre). Market prices fluctuate and may depend heavily on reputation as well as quality of truffles. In 2001, fresh truffles of the variety Tuber melanosporum were available on the Internet for about $225/kg ($500/pound). Other truffle species such as T. magnatum sell for about $765/kg ($1700/pound). The truffle industry is virtually unexplored in Oregon and there is potential to grow T. melanosporum in the Willamette Valley. This is a high risk crop due to the initial investment, a 10 year establishment period and fluctuations in yield and market values. Still, truffles are a low maintenance crop, can be sold worldwide and are highly acclaimed among gourmets. Also, truffle supply is limited, resulting in extreme high price. Socially and economically it appears that Tuber melanosporum could be a viable enterprise in the Willamette Valley. Title: Black truffle economics : evaluating the costs and returns of establishing and producing Tuber melanosporum in the Willamette Valley, Oregon. Author: Alvis, Heather E. The following paper is an objective view on the viability of growing the truffle Tuber melanosporum in the Willamette Valley. Included in this study are the history of the truffle, biological cycle, habitat description, method of cultivation and an enterprise budget for commercial production in the Willamette Valley. The truffle, a fungus that grows naturally underground, has long been a delicacy in European culture and it continues to appear in expensive restaurants around the world. The cultivation of T melanosporum was established first in Europe, but is gaining popularity in other parts of the world. Farms are appearing in Israel, Australia, The United States, New Zealand, and other nations. North Carolina and California also have operating truffle farms. Several species are currently cultivated in Europe, but the most prevalent and the only species cultivated outside of Europe is the Perigord (Black) truffle, Tuber melanosporum. Truffles are the fruiting bodies of various fungi. Spores produced within fruiting body germinate into tiny hair-like filaments (mycelia) that eventually attach themselves to the root tips of a host species and form mycorrhiza. After about six years, secondary mycelia emanating from the mycorrhizae grow together into a knot and form the fruiting body or carpophore. Host trees vary according to the location and species of truffle, however oak and hazelnut trees are most commonly used. Host trees that have been mycorrhized with truffles can be purchased from reputable growers for about $15 each. The climatic characteristics of the Willamette Valley are similar to those of major truffle growing regions in Europe. In addition, soils in the Willamette Valley may have an advantage because potentially competitive ectomycorrhizal fungi are adapted to acidic soils. T. melanosporum is grown in soils with high pH. Raising the soil pH for T. melanosporum could reduce the competition from native fungi adapted to acidic soils. Although few attempts have been made to cultivate truffles in Oregon, the Willamette Valley could be an ideal habitat for growing Tuber melanosporum. Establishment of a truffle farm takes 7 to 12 years depending on the species and the condition of the plot. Land must be free of plants that support ectomycorrhizal fungi, have evenly mixed sand, silt and clay (or well drained soils) and have an alkaline pH. An irrigation system should be installed in case of drought. After the trees are planted, maintenance of the truffle plot involves tilling the soil once a year, liming to maintain pH and pruning the host trees. Production typically begins after about six years and full production after about 10 years. Yields are difficult to estimate because truffle production is heavily influenced by weather conditions. In Europe, typical yields range from 50-150 kg per hectare (50-150 pounds per acre) in different plantations. The enterprise budget for a truffle farm in the Willamette Valley considers the costs and returns for a newly established farm. The budget is, by design, only a guide and does not consider individual differences among farmers. For example, it is expected that truffle cultivation will be an enterprise added to an existing farm, however the included budget includes costs of renting machinery for tilling. For a farmer that already owns his/her machinery, the budget must be altered accordingly. Truffles are expensive to produce. Profit and loss depend greatly on yield and price per pound. Also, commercial cultivation of truffles has not been achieved in Oregon and results are unpredictable. In good years, however some farms yield more than 100 kg per hectare (100 pounds per acre). Market prices fluctuate and may depend heavily on reputation as well as quality of truffles. In 2001, fresh truffles of the variety Tuber melanosporum were available on the Internet for about $225/kg ($500/pound). Other truffle species such as T. magnatum sell for about $765/kg ($1700/pound). The truffle industry is virtually unexplored in Oregon and there is potential to grow T. melanosporum in the Willamette Valley. This is a high risk crop due to the initial investment, a 10 year establishment period and fluctuations in yield and market values. Still, truffles are a low maintenance crop, can be sold worldwide and are highly acclaimed among gourmets. Also, truffle supply is limited, resulting in extreme high price. Socially and economically it appears that Tuber melanosporum could be a viable enterprise in the Willamette Valley. Close

• 2332. [Article] Greater Sage-grouse conservation assessment and strategy for Oregon: A plan to maintain and enhance populations and habitat

  Greater sage-grouse (Centrocercus urophasianus) were once found in most grassland and sagebrush (Artemisia spp.) habitats east of the Cascades in Oregon. European settlement and conversion of sagebrush ...

  Citation × Citation Citation Abstract Copy Title: Greater Sage-grouse conservation assessment and strategy for Oregon: A plan to maintain and enhance populations and habitat Author: Hagen, Christian Greater sage-grouse (Centrocercus urophasianus) were once found in most grassland and sagebrush (Artemisia spp.) habitats east of the Cascades in Oregon. European settlement and conversion of sagebrush steppe into agricultural production led to extirpation of the species in the Columbia Basin by the early part of the 1900s, but sagebrush rangelands have persisted, particularly in southeast Oregon. Populations have fluctuated markedly since the mid 1900s with notable declines in populations from the 1950s to early 1970s. These patterns in populations and habitat loss are similar to those observed for greater sage-grouse throughout its range. Population declines during the latter part of the 1900s lead to considerable concern for the species and subsequent conservation planning in all western states where it occurs. This management strategy is a result of this larger conservation effort by the Western Association of Fish and Wildlife Agencies. This updated and revised Plan describes Oregon Department of Fish and Wildlife’s management of greater sage-grouse and provides guidance to public land management agencies and land managers for sage-grouse conservation. Conservation actions should be encouraged on private lands as these contain some of the more productive sites, but conservation on private land is voluntary. Highlights of updates. Population goals have been revised based on statistically more robust methods for estimating population sizes. Accomplishments in conservation, research, and monitoring that have occurred since 2005 are discussed. The Core Area approach to strategically identifying important landscapes for sage-grouse is explained in detail from model development to implementation. Finally, there have been numerous publications on sage-grouse since 2005 and that literature has been updated to the document where appropriate. This management strategy and the supporting background information is intended to promote the conservation of greater sage-grouse and intact functioning sagebrush communities in Oregon. The strategy is tied to the life history of greater sage-grouse and uses the best science available. Although this strategy focuses on conservation of greater sage-grouse, the intent is to benefit conservation needs of other sagebrush-steppe species. Oregon greater sage-grouse are important to the North American population and management actions in the state will have implications on a much larger scale. This Plan recognizes that livestock ranching operations which manage for ecologically sustainable native rangelands is compatible with sage-grouse conservation, and necessary management activities to maintain a sustainable ranching operation are not considered “development actions” under the application of the Mitigation Policy to sage-grouse habitat. This Plan provides biological recommendations for long-term conservation of sage-grouse in Oregon based on the best available science. However, ODFW recognizes that land use planners and managers may need to consider these recommendations within the context of socialeconomic issues and decisions that are the responsibility of the respective governmental bodies. Thus, the intent of this plan is to inform decision-makers regarding the biological consequences of various actions on sage-grouse, but not to dictate land management decision. This document is divided into 6 sections. Section I explains the background and philosophy of conservation approaches in this strategy. Section II provides an overview of sage-grouse biology and ecology throughout the species range. Sections III and IV provide an assessment of populations and habitat, respectively, upon which management objectives are developed and their underlying assumptions and rationale are stated. In Section V, conservation guidelines are outlined, that describe actions needed and methods for achieving habitat objectives. Section VI outlines components for Plan implementation, includes a description of the structure and role of local implementation groups, and implications for public (state and federal) land management agencies. There are 6 appendices that provide supporting information, including a new appendix about socio-economics provided by the Association of Oregon Counties. Sections III to VI of the plan were expanded, because these sections are linked to the objectives and implementation of this Plan. Populations and habitat were assessed by BLM district boundaries because; the availability of habitat measures by district, each district approximates an eco-region, and BLM is the primary land manager within most of the district boundaries. The 23 years 1980-2003 are the relevant time period to establish a benchmark for sage-grouse populations and their habitats, because the factors of predator control methods (and take levels), grazing schedules, survey protocols, habitat treatments and harvest levels of sage-grouse were similar through this period. Title: Greater Sage-grouse conservation assessment and strategy for Oregon: A plan to maintain and enhance populations and habitat Author: Hagen, Christian Greater sage-grouse (Centrocercus urophasianus) were once found in most grassland and sagebrush (Artemisia spp.) habitats east of the Cascades in Oregon. European settlement and conversion of sagebrush steppe into agricultural production led to extirpation of the species in the Columbia Basin by the early part of the 1900s, but sagebrush rangelands have persisted, particularly in southeast Oregon. Populations have fluctuated markedly since the mid 1900s with notable declines in populations from the 1950s to early 1970s. These patterns in populations and habitat loss are similar to those observed for greater sage-grouse throughout its range. Population declines during the latter part of the 1900s lead to considerable concern for the species and subsequent conservation planning in all western states where it occurs. This management strategy is a result of this larger conservation effort by the Western Association of Fish and Wildlife Agencies. This updated and revised Plan describes Oregon Department of Fish and Wildlife’s management of greater sage-grouse and provides guidance to public land management agencies and land managers for sage-grouse conservation. Conservation actions should be encouraged on private lands as these contain some of the more productive sites, but conservation on private land is voluntary. Highlights of updates. Population goals have been revised based on statistically more robust methods for estimating population sizes. Accomplishments in conservation, research, and monitoring that have occurred since 2005 are discussed. The Core Area approach to strategically identifying important landscapes for sage-grouse is explained in detail from model development to implementation. Finally, there have been numerous publications on sage-grouse since 2005 and that literature has been updated to the document where appropriate. This management strategy and the supporting background information is intended to promote the conservation of greater sage-grouse and intact functioning sagebrush communities in Oregon. The strategy is tied to the life history of greater sage-grouse and uses the best science available. Although this strategy focuses on conservation of greater sage-grouse, the intent is to benefit conservation needs of other sagebrush-steppe species. Oregon greater sage-grouse are important to the North American population and management actions in the state will have implications on a much larger scale. This Plan recognizes that livestock ranching operations which manage for ecologically sustainable native rangelands is compatible with sage-grouse conservation, and necessary management activities to maintain a sustainable ranching operation are not considered “development actions” under the application of the Mitigation Policy to sage-grouse habitat. This Plan provides biological recommendations for long-term conservation of sage-grouse in Oregon based on the best available science. However, ODFW recognizes that land use planners and managers may need to consider these recommendations within the context of socialeconomic issues and decisions that are the responsibility of the respective governmental bodies. Thus, the intent of this plan is to inform decision-makers regarding the biological consequences of various actions on sage-grouse, but not to dictate land management decision. This document is divided into 6 sections. Section I explains the background and philosophy of conservation approaches in this strategy. Section II provides an overview of sage-grouse biology and ecology throughout the species range. Sections III and IV provide an assessment of populations and habitat, respectively, upon which management objectives are developed and their underlying assumptions and rationale are stated. In Section V, conservation guidelines are outlined, that describe actions needed and methods for achieving habitat objectives. Section VI outlines components for Plan implementation, includes a description of the structure and role of local implementation groups, and implications for public (state and federal) land management agencies. There are 6 appendices that provide supporting information, including a new appendix about socio-economics provided by the Association of Oregon Counties. Sections III to VI of the plan were expanded, because these sections are linked to the objectives and implementation of this Plan. Populations and habitat were assessed by BLM district boundaries because; the availability of habitat measures by district, each district approximates an eco-region, and BLM is the primary land manager within most of the district boundaries. The 23 years 1980-2003 are the relevant time period to establish a benchmark for sage-grouse populations and their habitats, because the factors of predator control methods (and take levels), grazing schedules, survey protocols, habitat treatments and harvest levels of sage-grouse were similar through this period. Close

• 2333. [Article] Impacts of Swiss needle cast on Douglas-fir tree-ring stable isotopes and tree carbohydrate reserves

  Understanding the mechanisms of disease in forest pathology is a critical component to learning how to most efficiently manage tree diseases like Swiss needle cast (SNC). SNC is an economically important, ...

  Citation × Citation Citation Abstract Copy Title: Impacts of Swiss needle cast on Douglas-fir tree-ring stable isotopes and tree carbohydrate reserves Author: Saffell, Brandy J. Understanding the mechanisms of disease in forest pathology is a critical component to learning how to most efficiently manage tree diseases like Swiss needle cast (SNC). SNC is an economically important, fungal disease of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) that is prevalent in coastal areas of the Pacific Northwest. This thesis research provides two contributions to the greater understanding of the pathogenic impacts on plant physiological functioning, or pathophysiology, of SNC on Douglas-fir that will ultimately inform management decisions in Pacific Northwest forests affected by SNC. The primary objectives of this thesis research were: (1) to examine the effects of SNC on Douglas-fir tree-ring stable isotope discrimination of carbon (Δ¹³C) and oxygen (δ¹⁸O) and (2) to evaluate the impact of SNC on tree carbohydrate reserves. Thesis Objective 1- I used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible reference species (western hemlock, Tsuga heterophylla (Raf.) Sarg.) to evaluate their use as proxies for variation in past SNC infection, particularly in relation to potential explanatory climate factors. Trees were sampled from a site where a fungicide trial took place from 1996 to 2000, which enabled the comparison of years when disease was present and absent, relative to untreated trees which had the infection throughout. Tree-ring Δ¹³C of treated Douglas-fir increased during the treatment period, and was ~1.6 per mil greater than that of untreated Douglas-fir at the end of the years of the fungicide treatment. Both annual growth and tree-ring Δ¹³C increased with treatment such that treated Douglas-fir had values similar to co-occurring western hemlock during the treatment period, which suggests that the use of Δ¹³C in Douglas-fir tree-rings to track SNC disease history may be a practical approach provided a reference species is available to develop a parallel Δ¹³C chronology. There was no difference in tree-ring δ¹⁸O between treated and untreated Douglas-fir. Tree-ring Δ¹³C of diseased Douglas-fir was negatively correlated with relative humidity (RH) during the two previous summers, consistent with increased leaf colonization by SNC under high humidity conditions that then lead to greater disease severity in following years. Thesis Objective 2- The effects of SNC on Douglas-fir carbohydrate reserves were explored to evaluate the extent to which non-structural carbohydrate (NSC) can be mobilized under natural conditions of low water stress and restricted carbon supply in relation to potential demands for growth. Concentrations of starch, sucrose, glucose and fructose were analyzed in twig wood, foliage, and trunk sapwood of 15 Douglas-fir trees expressing a gradient of SNC symptom severity. There were significant negative relationships between disease severity and growth (mean basal area increment, BAI), as well as between disease severity and mean concentration of trunk NSC. The amount of NSC per unit growth (mean NSC/BAI), an index of the relative priority of storage versus growth, increased with disease severity in all three sampled tissues. These results suggest that under reduced carbon supply with SNC, Douglas-fir trees retain NSC at the expense of growth. The crown retains the most NSC, presumably to maintain foliage growth in the spring to compensate for SNC-induced rapid foliage loss in the summer and fall. Title: Impacts of Swiss needle cast on Douglas-fir tree-ring stable isotopes and tree carbohydrate reserves Author: Saffell, Brandy J. Understanding the mechanisms of disease in forest pathology is a critical component to learning how to most efficiently manage tree diseases like Swiss needle cast (SNC). SNC is an economically important, fungal disease of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) that is prevalent in coastal areas of the Pacific Northwest. This thesis research provides two contributions to the greater understanding of the pathogenic impacts on plant physiological functioning, or pathophysiology, of SNC on Douglas-fir that will ultimately inform management decisions in Pacific Northwest forests affected by SNC. The primary objectives of this thesis research were: (1) to examine the effects of SNC on Douglas-fir tree-ring stable isotope discrimination of carbon (Δ¹³C) and oxygen (δ¹⁸O) and (2) to evaluate the impact of SNC on tree carbohydrate reserves. Thesis Objective 1- I used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible reference species (western hemlock, Tsuga heterophylla (Raf.) Sarg.) to evaluate their use as proxies for variation in past SNC infection, particularly in relation to potential explanatory climate factors. Trees were sampled from a site where a fungicide trial took place from 1996 to 2000, which enabled the comparison of years when disease was present and absent, relative to untreated trees which had the infection throughout. Tree-ring Δ¹³C of treated Douglas-fir increased during the treatment period, and was ~1.6 per mil greater than that of untreated Douglas-fir at the end of the years of the fungicide treatment. Both annual growth and tree-ring Δ¹³C increased with treatment such that treated Douglas-fir had values similar to co-occurring western hemlock during the treatment period, which suggests that the use of Δ¹³C in Douglas-fir tree-rings to track SNC disease history may be a practical approach provided a reference species is available to develop a parallel Δ¹³C chronology. There was no difference in tree-ring δ¹⁸O between treated and untreated Douglas-fir. Tree-ring Δ¹³C of diseased Douglas-fir was negatively correlated with relative humidity (RH) during the two previous summers, consistent with increased leaf colonization by SNC under high humidity conditions that then lead to greater disease severity in following years. Thesis Objective 2- The effects of SNC on Douglas-fir carbohydrate reserves were explored to evaluate the extent to which non-structural carbohydrate (NSC) can be mobilized under natural conditions of low water stress and restricted carbon supply in relation to potential demands for growth. Concentrations of starch, sucrose, glucose and fructose were analyzed in twig wood, foliage, and trunk sapwood of 15 Douglas-fir trees expressing a gradient of SNC symptom severity. There were significant negative relationships between disease severity and growth (mean basal area increment, BAI), as well as between disease severity and mean concentration of trunk NSC. The amount of NSC per unit growth (mean NSC/BAI), an index of the relative priority of storage versus growth, increased with disease severity in all three sampled tissues. These results suggest that under reduced carbon supply with SNC, Douglas-fir trees retain NSC at the expense of growth. The crown retains the most NSC, presumably to maintain foliage growth in the spring to compensate for SNC-induced rapid foliage loss in the summer and fall. Close

• 2334. [Article] The biology and pathogenicity of a sheath nematode Hemicycliophora similis Thorne, 1955

  A study, using greenhouse and laboratory experiments, was made of Hemicycliophora similis from Bandon, Oregon to determine: identity and morphometrics, time and development of a life cycle, host plant ...

  Citation × Citation Citation Abstract Copy Title: The biology and pathogenicity of a sheath nematode Hemicycliophora similis Thorne, 1955 Author: McKewan, Jeanette Anne A study, using greenhouse and laboratory experiments, was made of Hemicycliophora similis from Bandon, Oregon to determine: identity and morphometrics, time and development of a life cycle, host plant preferences and optimum environmental conditions for reproduction and pathogenicity. Morphometric investigations revealed discrepancies between the measurements of this nematode species and those recorded in nematological literature for H. similis. Personal communications with R. P. Esser, H. J. Jensen and B. M. Zuckerman suggested the variations noted do not necessitate describing a new species. For purposes of this research the nematode is named Hemicycliophora sirnilis. Life history investigations were conducted to determine the number of days required to complete a life cycle and the various stages as the nematode developed from egg to egg. Eggs mature to first-stage larvae, without sheath or spear, in 3-5 days and hatch as second-stage larvae in 8-10 days. Second-stage larvae inoculated onto carrot seedlings matured into third-stage larvae in 12-15 days. Fourth-stage larvae appeared in 25-28 days, and adults were present in 35-38 days. Embryonating eggs were observed lodged within an incompletely shed fourth-stage cuticle attached to adult females and within the normal sheath surrounding the adult. One molting specimen was found with two eggs lodged within the fourth-stage cuticle. Such eggs were seen to develop to second-stage larvae; however, none were observed over a long enough time period to determine if larvae hatched and emerged free of the cuticular confinement. Evaluated as hosts were beet, broccoli, carrot, corn, dill, pea, radish, rutabaga, tomato and turnip. Carrot, tomato and turnip supported the highest increase in population; no substantial increase was observed on beet, broccoli, corn and dill. The nematode formed galls consisting of large multibranched growths and reproduced on many of the plant species tested. Galling of seedling roots was most severe on carrot, but slight galling was observed on beet, rutabaga and turnip. Multibranching was observed with varying severity in all hosts. Germination of carrot seeds was reduced substantially when grown in sandy soil infested with H. similis. Slight germination reductions occurred with all hosts tested except corn and pea. Adults and larvae were observed feeding behind root tips and on nematode induced galls. Root discoloration was noted on several plants. To evaluate temperature and soil optima, rooted cranberry cuttings, germinated cranberry seedlings and carrot seedlings were utilized. Carrot seeds were planted in sandy soils of two different textures and pH, infested with H. similis and grown in three temperature regimes: 30°C and 24°C night, 22°C day and 14°C night and 30°C day 6 °C night. The optimum temperature for reproduction on carrot was 22°C day 14°C night in both soil types. A pH gradient developed in cups with the least acidic pH occurring at the base corresponding to maximum nutrient uptake by plant roots. The soil mix in which bog sand from Bandon was incorporated developed a more acidic condition presumably due to the additional organic N content which supplied ammonical nitrogen. The soil mix with Newport sand had no additional organic N and a less acidic condition developed. Maximum nematode population and root density also occurred at the base of the cup. Plants grown in infested soil had sparse multibranched roots; no galls were observed in this experiment. Cranberry cuttings were grown in sterile bog soil from Bandon, Oregon and inoculated with 225 nematodes/450 cc soil. The optimum temperature for nematode reproduction and plant growth was 30°C and 24°C night. Runner growth and root dry weights were not significantly effected by nematode feeding. Germinated cranberry seedlings were subjected to similar conditions; temperature response was similar to that of cuttings. Root dry weights and runner growth of cranberry seedlings was greater in nematode inoculated treatments than non-inoculated controls: nematode feeding on cranberry roots resulted in an increase of multibranching. This research indicated nematode feeding was detrimental to growth of a variety of plant species. High soil populations of H. similis caused severe reductions to root growth and seed germination. However, since this study was conducted in controlled conditions, it was not substantiated that this nematode caused a reduction of growth to field-grown cranberry plants. Further investigations are needed to correlate these findings with field data to determine pathogenicity on cranberry. Title: The biology and pathogenicity of a sheath nematode Hemicycliophora similis Thorne, 1955 Author: McKewan, Jeanette Anne A study, using greenhouse and laboratory experiments, was made of Hemicycliophora similis from Bandon, Oregon to determine: identity and morphometrics, time and development of a life cycle, host plant preferences and optimum environmental conditions for reproduction and pathogenicity. Morphometric investigations revealed discrepancies between the measurements of this nematode species and those recorded in nematological literature for H. similis. Personal communications with R. P. Esser, H. J. Jensen and B. M. Zuckerman suggested the variations noted do not necessitate describing a new species. For purposes of this research the nematode is named Hemicycliophora sirnilis. Life history investigations were conducted to determine the number of days required to complete a life cycle and the various stages as the nematode developed from egg to egg. Eggs mature to first-stage larvae, without sheath or spear, in 3-5 days and hatch as second-stage larvae in 8-10 days. Second-stage larvae inoculated onto carrot seedlings matured into third-stage larvae in 12-15 days. Fourth-stage larvae appeared in 25-28 days, and adults were present in 35-38 days. Embryonating eggs were observed lodged within an incompletely shed fourth-stage cuticle attached to adult females and within the normal sheath surrounding the adult. One molting specimen was found with two eggs lodged within the fourth-stage cuticle. Such eggs were seen to develop to second-stage larvae; however, none were observed over a long enough time period to determine if larvae hatched and emerged free of the cuticular confinement. Evaluated as hosts were beet, broccoli, carrot, corn, dill, pea, radish, rutabaga, tomato and turnip. Carrot, tomato and turnip supported the highest increase in population; no substantial increase was observed on beet, broccoli, corn and dill. The nematode formed galls consisting of large multibranched growths and reproduced on many of the plant species tested. Galling of seedling roots was most severe on carrot, but slight galling was observed on beet, rutabaga and turnip. Multibranching was observed with varying severity in all hosts. Germination of carrot seeds was reduced substantially when grown in sandy soil infested with H. similis. Slight germination reductions occurred with all hosts tested except corn and pea. Adults and larvae were observed feeding behind root tips and on nematode induced galls. Root discoloration was noted on several plants. To evaluate temperature and soil optima, rooted cranberry cuttings, germinated cranberry seedlings and carrot seedlings were utilized. Carrot seeds were planted in sandy soils of two different textures and pH, infested with H. similis and grown in three temperature regimes: 30°C and 24°C night, 22°C day and 14°C night and 30°C day 6 °C night. The optimum temperature for reproduction on carrot was 22°C day 14°C night in both soil types. A pH gradient developed in cups with the least acidic pH occurring at the base corresponding to maximum nutrient uptake by plant roots. The soil mix in which bog sand from Bandon was incorporated developed a more acidic condition presumably due to the additional organic N content which supplied ammonical nitrogen. The soil mix with Newport sand had no additional organic N and a less acidic condition developed. Maximum nematode population and root density also occurred at the base of the cup. Plants grown in infested soil had sparse multibranched roots; no galls were observed in this experiment. Cranberry cuttings were grown in sterile bog soil from Bandon, Oregon and inoculated with 225 nematodes/450 cc soil. The optimum temperature for nematode reproduction and plant growth was 30°C and 24°C night. Runner growth and root dry weights were not significantly effected by nematode feeding. Germinated cranberry seedlings were subjected to similar conditions; temperature response was similar to that of cuttings. Root dry weights and runner growth of cranberry seedlings was greater in nematode inoculated treatments than non-inoculated controls: nematode feeding on cranberry roots resulted in an increase of multibranching. This research indicated nematode feeding was detrimental to growth of a variety of plant species. High soil populations of H. similis caused severe reductions to root growth and seed germination. However, since this study was conducted in controlled conditions, it was not substantiated that this nematode caused a reduction of growth to field-grown cranberry plants. Further investigations are needed to correlate these findings with field data to determine pathogenicity on cranberry. Close

• 2335. [Article] Lichen communities and caribou habitat in Denali National Park and Preserve, Alaska, USA

  Lichens play many important roles in subarctic terrestrial ecosystems by fixing nitrogen, colonizing rock and gravel, stabilizing otherwise bare soil, adding significantly to vegetation biodiversity and ...

  Citation × Citation Citation Abstract Copy Title: Lichen communities and caribou habitat in Denali National Park and Preserve, Alaska, USA Author: Nelson, Peter, 1970- Lichens play many important roles in subarctic terrestrial ecosystems by fixing nitrogen, colonizing rock and gravel, stabilizing otherwise bare soil, adding significantly to vegetation biodiversity and serving as the primary food for caribou in the winter. In these chapters, I analyzed lichen community and ecological trait structure along environmental gradients, map lichens using some of their unique spectral properties to generate lichen maps and study caribou habitat selection patterns in relation to lichens and other habitat variables. Morphological and life history traits of lichens influence their ecological roles through physiological limitations imposed by their form and photobionts, the algal or cyanobacterial partner. In chapter 2, I analyzed the lichen traits in relationship to environmental gradients, other forms of vegetation and time since fire in Denali National Park and Preserve, Alaska. Lichens with different photobionts reached different maxima along environmental gradients, these corresponding to variable water availability or specific biotic factors thought to favor that photobiont. Green algal lichens were most abundant in the alpine whereas cyanolichens peaked where shrub cover increased. Tripartite lichens were most abundant in middle elevation, mossy areas. Lichen growthforms peaked along desiccation and water absorption gradients. Lichens with small vegetative propagules were most abundant in lowland forests. Recent fire favored simple, Cladonia-form lichens with soredia that grow on wood whereas erect branched fruticose lichens, the "reindeer lichens", had only partially recovered 20-100 years after fire. These results imply interacting forces of water regulation, dispersal and optimum conditions for photosynthesis drive lichen trait frequency and abundance. The fungal partner within the lichen symbiosis produces many unique compounds that are often brightly colored. Other studies have attempted to map lichens using their distinctive spectral properties but no study has yet to target specific lichen compounds in order to better model lichen cover. In chapter 3, I focused on one yellow lichen compound, usnic acid, as the target for modeling lichen cover using Landsat 7 ETM+ satellite data. Usnic lichen cover had non-linear relationships with the three best predictors; elevation, blue and near-infrared bandpasses. Using these three predictors, I generated an usnic lichen map for Denali, which I use in chapter 4 for analyzing caribou habitat selection. I also modeled and mapped other vegetation groups corresponding to caribou diet items used later. My results show that some lichens may be directly mapped from space by targeting this specific compound produced by the fungus. Caribou depend on lichens for up to 66% of their winter diet but other factors, such as snow, affect their access to the lichens. In chapter 4, I analyzed caribou habitat selection over 20 years in Denali using vegetation maps from chapter 3, climate data and other environmental variables. Over the two-decade period, caribou selected middle elevation, open areas with high graminoid cover and earlier snow-free dates. As each winter progressed, caribou aggregated where there was higher lichen cover and earlier snow-melt. Caribou selected habitat differently between years, which I collapsed into three different habitat/year groups: (1) years where most animals were in low elevation, flat terrain where there was low lichen and conifer cover but high graminoid and shrub cover with variable snow; (2) years caribou went to middle elevations with deeper snow and rugged terrain and moderate graminoid and lichen cover; and (3) years where caribou were dispersed west in low elevation woodlands with high lichen cover. My results show interacting factors determine caribou habitat selection at multiple spatial scales, specifically the importance of open, tussock tundra and long-term trends in snow melt at long time scales and lichen and snow-melt at shorter time scales. This research improves our understanding of the regional distribution and abundance of lichens in relation to higher plants, fire, and caribou. Title: Lichen communities and caribou habitat in Denali National Park and Preserve, Alaska, USA Author: Nelson, Peter, 1970- Lichens play many important roles in subarctic terrestrial ecosystems by fixing nitrogen, colonizing rock and gravel, stabilizing otherwise bare soil, adding significantly to vegetation biodiversity and serving as the primary food for caribou in the winter. In these chapters, I analyzed lichen community and ecological trait structure along environmental gradients, map lichens using some of their unique spectral properties to generate lichen maps and study caribou habitat selection patterns in relation to lichens and other habitat variables. Morphological and life history traits of lichens influence their ecological roles through physiological limitations imposed by their form and photobionts, the algal or cyanobacterial partner. In chapter 2, I analyzed the lichen traits in relationship to environmental gradients, other forms of vegetation and time since fire in Denali National Park and Preserve, Alaska. Lichens with different photobionts reached different maxima along environmental gradients, these corresponding to variable water availability or specific biotic factors thought to favor that photobiont. Green algal lichens were most abundant in the alpine whereas cyanolichens peaked where shrub cover increased. Tripartite lichens were most abundant in middle elevation, mossy areas. Lichen growthforms peaked along desiccation and water absorption gradients. Lichens with small vegetative propagules were most abundant in lowland forests. Recent fire favored simple, Cladonia-form lichens with soredia that grow on wood whereas erect branched fruticose lichens, the "reindeer lichens", had only partially recovered 20-100 years after fire. These results imply interacting forces of water regulation, dispersal and optimum conditions for photosynthesis drive lichen trait frequency and abundance. The fungal partner within the lichen symbiosis produces many unique compounds that are often brightly colored. Other studies have attempted to map lichens using their distinctive spectral properties but no study has yet to target specific lichen compounds in order to better model lichen cover. In chapter 3, I focused on one yellow lichen compound, usnic acid, as the target for modeling lichen cover using Landsat 7 ETM+ satellite data. Usnic lichen cover had non-linear relationships with the three best predictors; elevation, blue and near-infrared bandpasses. Using these three predictors, I generated an usnic lichen map for Denali, which I use in chapter 4 for analyzing caribou habitat selection. I also modeled and mapped other vegetation groups corresponding to caribou diet items used later. My results show that some lichens may be directly mapped from space by targeting this specific compound produced by the fungus. Caribou depend on lichens for up to 66% of their winter diet but other factors, such as snow, affect their access to the lichens. In chapter 4, I analyzed caribou habitat selection over 20 years in Denali using vegetation maps from chapter 3, climate data and other environmental variables. Over the two-decade period, caribou selected middle elevation, open areas with high graminoid cover and earlier snow-free dates. As each winter progressed, caribou aggregated where there was higher lichen cover and earlier snow-melt. Caribou selected habitat differently between years, which I collapsed into three different habitat/year groups: (1) years where most animals were in low elevation, flat terrain where there was low lichen and conifer cover but high graminoid and shrub cover with variable snow; (2) years caribou went to middle elevations with deeper snow and rugged terrain and moderate graminoid and lichen cover; and (3) years where caribou were dispersed west in low elevation woodlands with high lichen cover. My results show interacting factors determine caribou habitat selection at multiple spatial scales, specifically the importance of open, tussock tundra and long-term trends in snow melt at long time scales and lichen and snow-melt at shorter time scales. This research improves our understanding of the regional distribution and abundance of lichens in relation to higher plants, fire, and caribou. Close

• 2336. [Article] Ultraviolet radiation as an environmental stressor of amphibians

  My thesis explored the effects of and potential mediating mechanisms for an important environmental stressor, ultraviolet-B (UVB) radiation. UVB radiation has negative effects on organisms in both terrestrial ...

  Citation × Citation Citation Abstract Copy Title: Ultraviolet radiation as an environmental stressor of amphibians Author: Bancroft, Betsy A. My thesis explored the effects of and potential mediating mechanisms for an important environmental stressor, ultraviolet-B (UVB) radiation. UVB radiation has negative effects on organisms in both terrestrial and aquatic systems. I used meta-analysis to quantify the effects of UVB radiation on a diversity of aquatic organisms (Chapter 2). UVB negatively affects aquatic organisms by reducing both survival and growth. In particular, UVB reduces growth of embryos more than any other life history stage. Some taxonomic groups may be more affected by UVB radiation than others. In our analysis, the growth of members of the kingdom Protozoa was suppressed by UVB radiation to a greater degree than any other kingdom. These analyses suggest that UVB is an important stressor in both freshwater and marine systems. Amphibians are a common component of freshwater systems and are experiencing world-wide population declines. These declines may be due to a number of causes including habitat loss, introduced species, global climate change, disease, toxic chemicals and UVB radiation. I used meta-analytic techniques to quantify the effects of UVB radiation on amphibians. By synthesizing the results of 41 articles on the effects of UVB radiation on amphibians (Chapter 3), I found a nearly 2-fold reduction in survival of amphibians exposed to UVB radiation. Salamanders (caudates) appear to be more susceptible to damage from UVB than frogs or toads (anurans). Moreover, survival of larvae was much lower than survival of embryos or metamorphic individuals under UVB radiation. In addition, I used factorial meta-analytic techniques to explore the interaction between UVB radiation and other stressors in amphibian habitats. UVB radiation acted synergistically with other stressors to reduce survival of amphibians. Behavioral avoidance of UVB radiation may help mediate the negative effects of UVB radiation on amphibians. In aquatic systems, behavioral avoidance usually requires movement out of shallow water, where UVB levels can be high, into deeper waters with lower UVB transmittance. However, these two microhabitats have very different thermal profiles, creating a trade-off between exploiting warm waters with high UVB levels and avoiding UVB by seeking cooler, deeper regions of ponds. I explored the microhabitat use of larvae of four species through a series of laboratory experiments, field experiments, and observational field transects at three different amphibian habitats (Chapter 4). Larvae did not avoid UVB radiation in either the laboratory or field experiments. Larvae in thermal gradients selected relatively high temperatures regardless of the UVB exposure at these temperatures. In field transects, salamander larvae were most common in deeper, cooler waters where UVB levels were lower. In contrast, anuran larvae were frequently observed in the warmer and shallower regions of each habitat. These regions also had the highest UVB levels, suggesting that anuran larvae are exposed to high levels of UVB due to thermoregulatory behavior. Behavioral avoidance of UVB radiation is not the only mechanism amphibians may use to prevent damage from UVB. Pigments such as melanin may allow larvae to exploit warm shallow waters by absorbing harmful UVB radiation before it causes cellular damage. I tested the efficacy of melanin as a photoprotective pigment in the larvae of two species, Rana cascadae and Pseudacris regilla (Chapter 5). I found no evidence of a photoprotective function for melanin in these larvae. In contrast, lighter colored tadpoles grew more under UVB radiation compared to darker colored tadpoles. Overall, exposure to UVB reduced survival of P. regilla larvae and reduced growth of R. cascadae larvae. Larvae of both of these species were frequently observed in very shallow water with intense solar radiation. This thesis emphasizes the importance of UVB radiation as an environmental stressor in aquatic habitats. Many aquatic organisms are negatively affected by UVB exposure. My thesis work quantitatively demonstrated that UVB radiation is one factor that reduces survival of amphibians and suggests that some species are exposed to high levels of UVB radiation in natural habitats. While UVB radiation is not the sole cause of amphibian population declines, my work suggests that UVB radiation is an important stressor for amphibians that should not be overlooked. In addition, UVB radiation is clearly an important stressor for many other aquatic organisms. Future work should consider the effects of UVB in aquatic systems, particularly the effects of UVB radiation on community structure and ecosystem function. Title: Ultraviolet radiation as an environmental stressor of amphibians Author: Bancroft, Betsy A. My thesis explored the effects of and potential mediating mechanisms for an important environmental stressor, ultraviolet-B (UVB) radiation. UVB radiation has negative effects on organisms in both terrestrial and aquatic systems. I used meta-analysis to quantify the effects of UVB radiation on a diversity of aquatic organisms (Chapter 2). UVB negatively affects aquatic organisms by reducing both survival and growth. In particular, UVB reduces growth of embryos more than any other life history stage. Some taxonomic groups may be more affected by UVB radiation than others. In our analysis, the growth of members of the kingdom Protozoa was suppressed by UVB radiation to a greater degree than any other kingdom. These analyses suggest that UVB is an important stressor in both freshwater and marine systems. Amphibians are a common component of freshwater systems and are experiencing world-wide population declines. These declines may be due to a number of causes including habitat loss, introduced species, global climate change, disease, toxic chemicals and UVB radiation. I used meta-analytic techniques to quantify the effects of UVB radiation on amphibians. By synthesizing the results of 41 articles on the effects of UVB radiation on amphibians (Chapter 3), I found a nearly 2-fold reduction in survival of amphibians exposed to UVB radiation. Salamanders (caudates) appear to be more susceptible to damage from UVB than frogs or toads (anurans). Moreover, survival of larvae was much lower than survival of embryos or metamorphic individuals under UVB radiation. In addition, I used factorial meta-analytic techniques to explore the interaction between UVB radiation and other stressors in amphibian habitats. UVB radiation acted synergistically with other stressors to reduce survival of amphibians. Behavioral avoidance of UVB radiation may help mediate the negative effects of UVB radiation on amphibians. In aquatic systems, behavioral avoidance usually requires movement out of shallow water, where UVB levels can be high, into deeper waters with lower UVB transmittance. However, these two microhabitats have very different thermal profiles, creating a trade-off between exploiting warm waters with high UVB levels and avoiding UVB by seeking cooler, deeper regions of ponds. I explored the microhabitat use of larvae of four species through a series of laboratory experiments, field experiments, and observational field transects at three different amphibian habitats (Chapter 4). Larvae did not avoid UVB radiation in either the laboratory or field experiments. Larvae in thermal gradients selected relatively high temperatures regardless of the UVB exposure at these temperatures. In field transects, salamander larvae were most common in deeper, cooler waters where UVB levels were lower. In contrast, anuran larvae were frequently observed in the warmer and shallower regions of each habitat. These regions also had the highest UVB levels, suggesting that anuran larvae are exposed to high levels of UVB due to thermoregulatory behavior. Behavioral avoidance of UVB radiation is not the only mechanism amphibians may use to prevent damage from UVB. Pigments such as melanin may allow larvae to exploit warm shallow waters by absorbing harmful UVB radiation before it causes cellular damage. I tested the efficacy of melanin as a photoprotective pigment in the larvae of two species, Rana cascadae and Pseudacris regilla (Chapter 5). I found no evidence of a photoprotective function for melanin in these larvae. In contrast, lighter colored tadpoles grew more under UVB radiation compared to darker colored tadpoles. Overall, exposure to UVB reduced survival of P. regilla larvae and reduced growth of R. cascadae larvae. Larvae of both of these species were frequently observed in very shallow water with intense solar radiation. This thesis emphasizes the importance of UVB radiation as an environmental stressor in aquatic habitats. Many aquatic organisms are negatively affected by UVB exposure. My thesis work quantitatively demonstrated that UVB radiation is one factor that reduces survival of amphibians and suggests that some species are exposed to high levels of UVB radiation in natural habitats. While UVB radiation is not the sole cause of amphibian population declines, my work suggests that UVB radiation is an important stressor for amphibians that should not be overlooked. In addition, UVB radiation is clearly an important stressor for many other aquatic organisms. Future work should consider the effects of UVB in aquatic systems, particularly the effects of UVB radiation on community structure and ecosystem function. Close

• 2337. [Article] An analysis of a population of snowshoe hares, Lepus americanus washingtonii Baird, in western Oregon

  The ecology of a population of snowshoe hares, Lepus americanus washingtonii, was studied in western Oregon from 1960 to 1962. Objectives were to obtain information to control hares, which frequently cause ...

  Citation × Citation Citation Abstract Copy Title: An analysis of a population of snowshoe hares, Lepus americanus washingtonii Baird, in western Oregon Author: Black, Hugh C., 1941- The ecology of a population of snowshoe hares, Lepus americanus washingtonii, was studied in western Oregon from 1960 to 1962. Objectives were to obtain information to control hares, which frequently cause damage to coniferous reproduction in the region, and to compare the life history of this little-studied subspecies with others. The study area was located on cut-over forest land at 2900-foot elevation in the western Cascades. The climate is characterized by heavy precipitation in winter and summer drought. Snowfall is slight. Sixty-four live-traps were located in a square grid of 8 rows of 8 traps each, at spacings of approximately 100 and 200 feet. Half the traps were located on a recently clear-cut area and half in young-growth western hemlock and Douglas-fir. Traps usually were set for three successive days at monthly intervals. Trapped hares were marked and released on the main study area, and hares from nearby areas were removed for necropsy. In all, 207 hares were caught 889 times on the trapping grid during the 18-month study. One-third of hares tagged and released were not recaught, but the remainder were recaught one or more times. Trapping success varied from 3.6 to 44.4 percent. Principle factors influencing movements of hares, trapping success, and distribution of catches were vegetative structure, weather, and differing behavior of adults. Estimates of numbers of hares were computed from live-trapping data by the recapture, and the calendar-graph methods. Both methods indicated comparable trends in the population. Estimates of hares on the area trapped ranged from 41 in March to 136 in August. Estimated density of hares was 1.6 per acre at start of trapping in October. Density was nearly doubled to about 3.0 hares per acre in late summer. Most adult females on the area studied had two or three litters a year, averaging three young per litter. First litters were born in May and last litters in August. Most juveniles approached maximum size by four months. Mean total length of adults of both sexes was greater than that of subadults. Foot and total length of adult females were greater than in adult males. Mean weight of adult males in winter was 40.6 ounces and of females, 43.4 ounces. Subadults and adults weighed slightly less in early winter than in late fall. Sex ratio of 205 adult and juvenile hares was 80 females to 100 males; ratio of 84 young juveniles tagged during the summer was 87 females to 100 males. Juveniles tagged (154) exceeded adults tagged (51) by a ratio of 3:1. Weighted mean range-size of adult hares caught three or more times as computed by the inclusive-boundary-strip, and circular-bivariant-distribution methods was 5.76 and 10.15 acres for males; 3.30 and 7.80 acres for females. Mean home range of juveniles was comparable to the range of adult females. Distribution of catches of hares repeatedly caught and tracking of toe-clipped hares showed that trap-revealed ranges are related to true ranges and that ranges of most adults are fairly stable. A tendency towards farther ranging and linearity of movements was shown by some hares in winter. Location and use of forms are described. Signs of feeding showed that hares fed on conifers and shrubs in winter and herbaceous vegetation in summer. Young juvenile hares "disappeared" from the population at a high rate. Probability of their survival from birth to the first breeding season was less than 0.18. Crude survival rate of all hares was 0.73. Neither disease nor parasitism constituted serious decimating factors, and pathology of 74 hares necropsied was normal. Predation was the most important source of mortality among hares of all ages. Symptoms of "trap sickness" were shown, mainly in winter, by 29 of 207 hares. The following parasites were found in 50 necropsied hares, and 207 hares examined for ticks and fleas: Protozoa, Eimeria stiedae; Cestoda, Mosgovoyia pectinata americana, and Taenia pisiformis; Nematoda, Trichostrongylus affinis, and Nematodirus triangularis; Acarina, Haemphysalis leporis-palustris; and Siphonaptera, Cediopsyllus simplex and Hoplopsyllus affinis. Title: An analysis of a population of snowshoe hares, Lepus americanus washingtonii Baird, in western Oregon Author: Black, Hugh C., 1941- The ecology of a population of snowshoe hares, Lepus americanus washingtonii, was studied in western Oregon from 1960 to 1962. Objectives were to obtain information to control hares, which frequently cause damage to coniferous reproduction in the region, and to compare the life history of this little-studied subspecies with others. The study area was located on cut-over forest land at 2900-foot elevation in the western Cascades. The climate is characterized by heavy precipitation in winter and summer drought. Snowfall is slight. Sixty-four live-traps were located in a square grid of 8 rows of 8 traps each, at spacings of approximately 100 and 200 feet. Half the traps were located on a recently clear-cut area and half in young-growth western hemlock and Douglas-fir. Traps usually were set for three successive days at monthly intervals. Trapped hares were marked and released on the main study area, and hares from nearby areas were removed for necropsy. In all, 207 hares were caught 889 times on the trapping grid during the 18-month study. One-third of hares tagged and released were not recaught, but the remainder were recaught one or more times. Trapping success varied from 3.6 to 44.4 percent. Principle factors influencing movements of hares, trapping success, and distribution of catches were vegetative structure, weather, and differing behavior of adults. Estimates of numbers of hares were computed from live-trapping data by the recapture, and the calendar-graph methods. Both methods indicated comparable trends in the population. Estimates of hares on the area trapped ranged from 41 in March to 136 in August. Estimated density of hares was 1.6 per acre at start of trapping in October. Density was nearly doubled to about 3.0 hares per acre in late summer. Most adult females on the area studied had two or three litters a year, averaging three young per litter. First litters were born in May and last litters in August. Most juveniles approached maximum size by four months. Mean total length of adults of both sexes was greater than that of subadults. Foot and total length of adult females were greater than in adult males. Mean weight of adult males in winter was 40.6 ounces and of females, 43.4 ounces. Subadults and adults weighed slightly less in early winter than in late fall. Sex ratio of 205 adult and juvenile hares was 80 females to 100 males; ratio of 84 young juveniles tagged during the summer was 87 females to 100 males. Juveniles tagged (154) exceeded adults tagged (51) by a ratio of 3:1. Weighted mean range-size of adult hares caught three or more times as computed by the inclusive-boundary-strip, and circular-bivariant-distribution methods was 5.76 and 10.15 acres for males; 3.30 and 7.80 acres for females. Mean home range of juveniles was comparable to the range of adult females. Distribution of catches of hares repeatedly caught and tracking of toe-clipped hares showed that trap-revealed ranges are related to true ranges and that ranges of most adults are fairly stable. A tendency towards farther ranging and linearity of movements was shown by some hares in winter. Location and use of forms are described. Signs of feeding showed that hares fed on conifers and shrubs in winter and herbaceous vegetation in summer. Young juvenile hares "disappeared" from the population at a high rate. Probability of their survival from birth to the first breeding season was less than 0.18. Crude survival rate of all hares was 0.73. Neither disease nor parasitism constituted serious decimating factors, and pathology of 74 hares necropsied was normal. Predation was the most important source of mortality among hares of all ages. Symptoms of "trap sickness" were shown, mainly in winter, by 29 of 207 hares. The following parasites were found in 50 necropsied hares, and 207 hares examined for ticks and fleas: Protozoa, Eimeria stiedae; Cestoda, Mosgovoyia pectinata americana, and Taenia pisiformis; Nematoda, Trichostrongylus affinis, and Nematodirus triangularis; Acarina, Haemphysalis leporis-palustris; and Siphonaptera, Cediopsyllus simplex and Hoplopsyllus affinis. Close

• 2338. [Article] Responsive pedagogies of practice : researching an ambitious secondary mathematics teacher education design

  Design in secondary mathematics teacher education must prepare teacher candidates to do the work of ambitious and equitable mathematics teaching with skill by situating development in the work of teaching ...

  Citation × Citation Citation Abstract Copy Title: Responsive pedagogies of practice : researching an ambitious secondary mathematics teacher education design Author: Campbell, Matthew Paul, 1983- Design in secondary mathematics teacher education must prepare teacher candidates to do the work of ambitious and equitable mathematics teaching with skill by situating development in the work of teaching and incorporating opportunities to investigate and enact teaching. Teacher education designs must also be responsive to the work that mathematics teachers are expected to do in school settings--which are a product of a set of goals, expectations, and communities that have formed over long histories. This dissertation pursues novel and emerging questions around what the design and implementation of a responsive and practice-focused approach to teacher education--what I call a responsive pedagogy of practice--entails, how those entailments are informed by the work of teaching in schools, and how those entailments inform what individuals do in teacher education programs. Three manuscripts collectively illustrate progress on these ideas, drawing upon data and analyses from design-based research in a secondary mathematics teacher education program. The first manuscript addresses a question of what is meant by and entailed in the design and implementation of a responsive pedagogy of practice. Through an intertwined process of design, implementation, analyses, and revision, three sets of findings informing the development of a theory of responsive pedagogies of practice emerged. First, two needs emerged in addition to the initial attention to developing teacher candidates' instructional skill--aligning with the mathematics of the secondary classroom and developing teacher candidates’ mathematical knowledge for teaching (MKT; Ball, Thames, & Phelps, 2008). The negotiation of these multiple needs poses a challenge for teacher educators. This negotiation also gave rise to a second finding involving the development of instructional skill, which needs to focus on the development on multiple levels of pedagogical tools. Further, a set of pedagogical tools must be derived, in part, from the work that teacher candidates do in school settings. Ultimately, this means that responsiveness in teacher education entails preparing teacher candidates to do what is typically done in school settings while also finding the openings at which to press for more ambitious and equitable teaching practice. Finally, a third finding emerged regarding the novel roles for teacher educators and partner teachers that are constructed through a responsive and practice-focused pedagogy of teacher education. The second manuscript highlights analyses conducted to further investigate the features of the activity of secondary mathematics teaching to which a teacher education design needs to be responsive. Data from teacher candidates' enactments across two settings--the university methods courses and their student teaching placements--were drawn upon to identify the entailments of the activity of secondary mathematics teaching. A modified analytic framework from Leont’ev (1981) and Wertsch, Minick, and Arns (1984) was used to analyze the work of teacher candidates in each setting. While the work in the methods courses emphasized providing students access to mathematics and the orchestration of goal-directed discussions, work in student teaching placements was defined by efficient and productive work on mathematical procedures. Opportunities for more novel instruction were made available contingent on the two expectations being met. These findings have implications for what pedagogical tools should be developed through a responsive pedagogy of practice that enable efficient and procedurally focused mathematics work while also making progress on increasingly ambitious and equitable instruction. The third manuscript highlights an example of how an emerging sense of responsive and practice-focused approaches to teacher education and the work of teacher candidates in school classrooms inform the design features of a responsive pedagogy of practice. A specific design example is put forth that situates opportunities of enactment in the work of addressing students' mathematics errors in the midst of work with students on mathematics procedures. As such, the example is derived from the work that teacher candidates do in school classrooms and also shows how a design can attend to the multiple needs related to teacher candidate and student development. The example serves as one of many activities in development--all of which are subject to further examination through a design-based research process. Title: Responsive pedagogies of practice : researching an ambitious secondary mathematics teacher education design Author: Campbell, Matthew Paul, 1983- Design in secondary mathematics teacher education must prepare teacher candidates to do the work of ambitious and equitable mathematics teaching with skill by situating development in the work of teaching and incorporating opportunities to investigate and enact teaching. Teacher education designs must also be responsive to the work that mathematics teachers are expected to do in school settings--which are a product of a set of goals, expectations, and communities that have formed over long histories. This dissertation pursues novel and emerging questions around what the design and implementation of a responsive and practice-focused approach to teacher education--what I call a responsive pedagogy of practice--entails, how those entailments are informed by the work of teaching in schools, and how those entailments inform what individuals do in teacher education programs. Three manuscripts collectively illustrate progress on these ideas, drawing upon data and analyses from design-based research in a secondary mathematics teacher education program. The first manuscript addresses a question of what is meant by and entailed in the design and implementation of a responsive pedagogy of practice. Through an intertwined process of design, implementation, analyses, and revision, three sets of findings informing the development of a theory of responsive pedagogies of practice emerged. First, two needs emerged in addition to the initial attention to developing teacher candidates' instructional skill--aligning with the mathematics of the secondary classroom and developing teacher candidates’ mathematical knowledge for teaching (MKT; Ball, Thames, & Phelps, 2008). The negotiation of these multiple needs poses a challenge for teacher educators. This negotiation also gave rise to a second finding involving the development of instructional skill, which needs to focus on the development on multiple levels of pedagogical tools. Further, a set of pedagogical tools must be derived, in part, from the work that teacher candidates do in school settings. Ultimately, this means that responsiveness in teacher education entails preparing teacher candidates to do what is typically done in school settings while also finding the openings at which to press for more ambitious and equitable teaching practice. Finally, a third finding emerged regarding the novel roles for teacher educators and partner teachers that are constructed through a responsive and practice-focused pedagogy of teacher education. The second manuscript highlights analyses conducted to further investigate the features of the activity of secondary mathematics teaching to which a teacher education design needs to be responsive. Data from teacher candidates' enactments across two settings--the university methods courses and their student teaching placements--were drawn upon to identify the entailments of the activity of secondary mathematics teaching. A modified analytic framework from Leont’ev (1981) and Wertsch, Minick, and Arns (1984) was used to analyze the work of teacher candidates in each setting. While the work in the methods courses emphasized providing students access to mathematics and the orchestration of goal-directed discussions, work in student teaching placements was defined by efficient and productive work on mathematical procedures. Opportunities for more novel instruction were made available contingent on the two expectations being met. These findings have implications for what pedagogical tools should be developed through a responsive pedagogy of practice that enable efficient and procedurally focused mathematics work while also making progress on increasingly ambitious and equitable instruction. The third manuscript highlights an example of how an emerging sense of responsive and practice-focused approaches to teacher education and the work of teacher candidates in school classrooms inform the design features of a responsive pedagogy of practice. A specific design example is put forth that situates opportunities of enactment in the work of addressing students' mathematics errors in the midst of work with students on mathematics procedures. As such, the example is derived from the work that teacher candidates do in school classrooms and also shows how a design can attend to the multiple needs related to teacher candidate and student development. The example serves as one of many activities in development--all of which are subject to further examination through a design-based research process. Close

• 2339. [Article] Drought, dispersal, and community dynamics in arid-land streams

  Understanding the mechanisms that regulate local species diversity and community structure is a perennial goal of ecology. Local community structure can be viewed as the result of numerous local and regional ...

  Citation × Citation Citation Abstract Copy Title: Drought, dispersal, and community dynamics in arid-land streams Author: Bogan, Michael T. Understanding the mechanisms that regulate local species diversity and community structure is a perennial goal of ecology. Local community structure can be viewed as the result of numerous local and regional processes; these processes act as filters that reduce the regional species pool down to the observed local community. In stream ecosystems, the natural flow regime (including the timing, magnitude, and duration of high and low flow events) is widely recognized as a primary regulator of local diversity and community composition. This is especially true in aridland streams, where low- and zero-flow events can occur frequently and for extended periods of time (months to years). Additionally, wetted habitat patches in arid-land stream networks are often fragmented within and among stream networks. Thus dispersal between isolated aquatic patches may also play a large role in regulating local communities. In my dissertation, I explored the roles that drought, dispersal, and local habitat factors play in structuring arid-land stream communities. I examined the impact of flow permanence and seasonal variation in flow and other abiotic factors on aquatic communities at both fine spatial scales over a long time period (8 years; Chapter 2) and at a broad spatial scale over a shorter time period (1-2 years; Chapter 4). Additionally, I quantified aquatic invertebrate aerial dispersal over moderate spatial scales (≤ 0.5 km) by conducting a colonization experiment using artificial stream pools placed along and inland from two arid-land streams (Chapter 4). Finally, I examined the roles of spatial isolation, microhabitat type, and local abiotic and biotic factors in structuring aquatic communities in freshwater oases scattered across one of the most arid regions of North America, the southern Sonoran Desert (Chapter 5). In Chapter 2, I found that severe drought caused an unprecedented drying event in isolated perennial stream pools, and that several additional drying events occurred over the following four years. This transition to intermittent flow caused the extirpation of several large, long-lived species with low dispersal abilities (including the top predator) and drove the local community into an alternative state. In the colonization experiment described in Chapter 3, I found that several arid-land stream invertebrate taxa disperse widely and frequently. The widespread dispersers identified by this experiment included several of the earliest colonist taxa observed following the severe drought described in Chapter 2. Other taxa, though, only dispersed overland after receiving an environmental cue (rainfall) or preferentially dispersed along stream corridors. In Chapter 4, where I examined invertebrate community structure across a large network of well-connected intermittent and perennial reaches, I found low diversity in intermittent reaches, regardless of their connectivity to diverse upstream perennial reaches. These species-poor, intermittent communities were composed of a unique suite of species with lifehistory adaptations that conferred desiccation resistance, including extended egg and larval diapause stages. The short flow duration of intermittent reaches (<100 days) likely precluded upstream perennial taxa from establishing populations in downstream intermittent reaches before drying occurred, while the relative predictability of flow timing (Dec-Apr) likely allowed for a small number of species to develop appropriate life-history traits (e.g., diapause stage, rapid development time) to exploit these temporally-fleeting habitats. In Chapter 5, I found over 220 species of aquatic animals (including ≥ 5 undescribed species) in the 19 desert oases that were sampled across the southern Sonoran Desert. Local community composition in these oases was strongly driven by microhabitat type. Additionally, native aquatic species richness and abundance in these oases were significantly reduced by the introduction of tilapia, an exotic fish species. The threats to arid-land streams presented by increased drought severity, anthropogenic water withdrawals, and local habitat degradation (e.g., introduced species, unmanaged recreational use) are grave across the southwestern US and northwestern Mexico. I hope that in addition to furthering our understanding of ecological processes in arid-land streams, this dissertation makes a small contribution towards the efforts to preserve these habitats. Title: Drought, dispersal, and community dynamics in arid-land streams Author: Bogan, Michael T. Understanding the mechanisms that regulate local species diversity and community structure is a perennial goal of ecology. Local community structure can be viewed as the result of numerous local and regional processes; these processes act as filters that reduce the regional species pool down to the observed local community. In stream ecosystems, the natural flow regime (including the timing, magnitude, and duration of high and low flow events) is widely recognized as a primary regulator of local diversity and community composition. This is especially true in aridland streams, where low- and zero-flow events can occur frequently and for extended periods of time (months to years). Additionally, wetted habitat patches in arid-land stream networks are often fragmented within and among stream networks. Thus dispersal between isolated aquatic patches may also play a large role in regulating local communities. In my dissertation, I explored the roles that drought, dispersal, and local habitat factors play in structuring arid-land stream communities. I examined the impact of flow permanence and seasonal variation in flow and other abiotic factors on aquatic communities at both fine spatial scales over a long time period (8 years; Chapter 2) and at a broad spatial scale over a shorter time period (1-2 years; Chapter 4). Additionally, I quantified aquatic invertebrate aerial dispersal over moderate spatial scales (≤ 0.5 km) by conducting a colonization experiment using artificial stream pools placed along and inland from two arid-land streams (Chapter 4). Finally, I examined the roles of spatial isolation, microhabitat type, and local abiotic and biotic factors in structuring aquatic communities in freshwater oases scattered across one of the most arid regions of North America, the southern Sonoran Desert (Chapter 5). In Chapter 2, I found that severe drought caused an unprecedented drying event in isolated perennial stream pools, and that several additional drying events occurred over the following four years. This transition to intermittent flow caused the extirpation of several large, long-lived species with low dispersal abilities (including the top predator) and drove the local community into an alternative state. In the colonization experiment described in Chapter 3, I found that several arid-land stream invertebrate taxa disperse widely and frequently. The widespread dispersers identified by this experiment included several of the earliest colonist taxa observed following the severe drought described in Chapter 2. Other taxa, though, only dispersed overland after receiving an environmental cue (rainfall) or preferentially dispersed along stream corridors. In Chapter 4, where I examined invertebrate community structure across a large network of well-connected intermittent and perennial reaches, I found low diversity in intermittent reaches, regardless of their connectivity to diverse upstream perennial reaches. These species-poor, intermittent communities were composed of a unique suite of species with lifehistory adaptations that conferred desiccation resistance, including extended egg and larval diapause stages. The short flow duration of intermittent reaches (<100 days) likely precluded upstream perennial taxa from establishing populations in downstream intermittent reaches before drying occurred, while the relative predictability of flow timing (Dec-Apr) likely allowed for a small number of species to develop appropriate life-history traits (e.g., diapause stage, rapid development time) to exploit these temporally-fleeting habitats. In Chapter 5, I found over 220 species of aquatic animals (including ≥ 5 undescribed species) in the 19 desert oases that were sampled across the southern Sonoran Desert. Local community composition in these oases was strongly driven by microhabitat type. Additionally, native aquatic species richness and abundance in these oases were significantly reduced by the introduction of tilapia, an exotic fish species. The threats to arid-land streams presented by increased drought severity, anthropogenic water withdrawals, and local habitat degradation (e.g., introduced species, unmanaged recreational use) are grave across the southwestern US and northwestern Mexico. I hope that in addition to furthering our understanding of ecological processes in arid-land streams, this dissertation makes a small contribution towards the efforts to preserve these habitats. Close

• 2340. [Article] The influence of social structure and molecular evolution on genetic diversity in the sperm whale (Physeter macrocephalus)

  The sperm whale (Physeter macrocephalus) shows some of the most derived characteristics of any mammal: a large body size, large brain, complex social organization and a capacity for deep foraging dives ...

  Citation × Citation Citation Abstract Copy Title: The influence of social structure and molecular evolution on genetic diversity in the sperm whale (Physeter macrocephalus) Author: Alexander, Alana The sperm whale (Physeter macrocephalus) shows some of the most derived characteristics of any mammal: a large body size, large brain, complex social organization and a capacity for deep foraging dives that few other marine mammals can match. Despite a history of exploitation that removed hundreds of thousands of individuals, the sperm whale population remains relatively abundant in comparison with other large whale species. Given this abundance, and the sperm whale's matrifocal social organization, it is surprising that previous research found that mitochondrial DNA control region (mtDNA CR) diversity in sperm whales is extremely low and population structure is relatively limited within oceans. This dissertation addresses several questions spanning evolutionary and ecological time scales, including whether the low levels of mtDNA CR diversity and differentiation seen in the sperm whale have been limited by sample size and geographic scope in previous studies; how sperm whale genetic diversity is partitioned at several hierarchical levels; and hypotheses explaining the low mtDNA CR diversity. To achieve this, I generated DNA profiles representing 557 individuals from circum-equatorial regions, strandings around the coasts of New Zealand, Samoa and Oregon, and biopsy samples from the Gulf of Mexico. DNA genotypes constructed from these samples (mtDNA CR, sex, 13 microsatellite loci), and mtDNA information from 1,167 previously published samples, indicated a high degree of mtDNA CR differentiation within the previously un-sampled Indian Ocean (FST 0.314, p < 0.001). The level of differentiation seen was similar to that found with the marginal seas of the Atlantic i.e. the Gulf of Mexico and the Mediterranean (FST 0.469, p < 0.001). In contrast, levels of mtDNA differentiation seen in the Pacific were much lower (FST 0.061, p < 0.001). Microsatellite differentiation was much less marked for all three oceans, consistent with tests indicating male-biased dispersal and gene flow. In addition to regional differentiation, significant differentiation was seen among social groups. However, the magnitude of this differentiation differed by ocean. Hierarchical mtDNA analyses showed that in the Pacific, 'social group' explained more variance than geographic region. In contrast, in the Indian Ocean, regions explained more variance than social group. In the Atlantic, the number of social groups within regions was too limited to make conclusions. Social group was the only level that explained significant variation in microsatellite allele frequencies in any ocean. Increased relatedness within social groups does not appear to explain the microsatellite differentiation. Instead, the likely explanation is different breeding males consorting with different female-dominated social groups. mtDNA differentiation seen among social groups appears to be driven by ‘lenient matrilineality', where 38% of groups were strictly matrilineal, and a further 25% of groups were comprised of more than one matriline, but fewer matrilines than expected by chance. However, the levels of matrilineality are too low to be consistent with the previously proposed hypothesis of a selective sweep linked with maternal cultural innovations as an explanation for low mtDNA diversity in the sperm whale. To examine alternative hypotheses for low mtDNA diversity, next-generation sequencing (454 and Illumina) was used to sequence mitogenomes for 17 Pacific Ocean sperm whale samples, with other cetacean mitogenomes compiled from the literature. Using these mitogenomes, no evidence of slow substitution rates were found in the mtDNA CR or protein-coding genes of the mitogenome that could explain the low diversity. In addition, the mtDNA CR had the highest diversity of the entire mitogenome and showed genealogical patterns concordant with the rest of the mitogenome. This discounts mtDNA CR-specific constraints as the cause of low mtDNA CR diversity. To investigate the remaining hypotheses of a selective sweep, population bottleneck or expansion, 8 nuclear loci (~12,000 bp) were sequenced for 22 sperm whales (Pacific and Gulf of Mexico), and compared to 10 New Zealand pygmy sperm whales (Kogia breviceps). The results were inconsistent with a selective sweep and showed instead low diversity across both mtDNA and nuclear DNA, in comparison to the higher levels of genetic diversity in the pygmy sperm whale and other cetacean species. Demographic reconstructions showed the sperm whale to have had a stable, but small, population size for much of historical time. This suggests a recent population expansion is responsible for the low mtDNA (and nuclear DNA) diversity in the sperm whale. The inferred timing of the expansion corresponds with expansions in squid species (the primary prey of the sperm whale), and explains shared mtDNA haplotypes between oceans. Since this expansion, the marked philopatry shown by female sperm whales at various hierarchical levels ranging from social groups (e.g. lenient matrilineality) to broader geographic scales, has led to maternally-mediated genetic drift driving striking differences in mtDNA haplotype frequencies between social groups, regions, and oceans. Title: The influence of social structure and molecular evolution on genetic diversity in the sperm whale (Physeter macrocephalus) Author: Alexander, Alana The sperm whale (Physeter macrocephalus) shows some of the most derived characteristics of any mammal: a large body size, large brain, complex social organization and a capacity for deep foraging dives that few other marine mammals can match. Despite a history of exploitation that removed hundreds of thousands of individuals, the sperm whale population remains relatively abundant in comparison with other large whale species. Given this abundance, and the sperm whale's matrifocal social organization, it is surprising that previous research found that mitochondrial DNA control region (mtDNA CR) diversity in sperm whales is extremely low and population structure is relatively limited within oceans. This dissertation addresses several questions spanning evolutionary and ecological time scales, including whether the low levels of mtDNA CR diversity and differentiation seen in the sperm whale have been limited by sample size and geographic scope in previous studies; how sperm whale genetic diversity is partitioned at several hierarchical levels; and hypotheses explaining the low mtDNA CR diversity. To achieve this, I generated DNA profiles representing 557 individuals from circum-equatorial regions, strandings around the coasts of New Zealand, Samoa and Oregon, and biopsy samples from the Gulf of Mexico. DNA genotypes constructed from these samples (mtDNA CR, sex, 13 microsatellite loci), and mtDNA information from 1,167 previously published samples, indicated a high degree of mtDNA CR differentiation within the previously un-sampled Indian Ocean (FST 0.314, p < 0.001). The level of differentiation seen was similar to that found with the marginal seas of the Atlantic i.e. the Gulf of Mexico and the Mediterranean (FST 0.469, p < 0.001). In contrast, levels of mtDNA differentiation seen in the Pacific were much lower (FST 0.061, p < 0.001). Microsatellite differentiation was much less marked for all three oceans, consistent with tests indicating male-biased dispersal and gene flow. In addition to regional differentiation, significant differentiation was seen among social groups. However, the magnitude of this differentiation differed by ocean. Hierarchical mtDNA analyses showed that in the Pacific, 'social group' explained more variance than geographic region. In contrast, in the Indian Ocean, regions explained more variance than social group. In the Atlantic, the number of social groups within regions was too limited to make conclusions. Social group was the only level that explained significant variation in microsatellite allele frequencies in any ocean. Increased relatedness within social groups does not appear to explain the microsatellite differentiation. Instead, the likely explanation is different breeding males consorting with different female-dominated social groups. mtDNA differentiation seen among social groups appears to be driven by ‘lenient matrilineality', where 38% of groups were strictly matrilineal, and a further 25% of groups were comprised of more than one matriline, but fewer matrilines than expected by chance. However, the levels of matrilineality are too low to be consistent with the previously proposed hypothesis of a selective sweep linked with maternal cultural innovations as an explanation for low mtDNA diversity in the sperm whale. To examine alternative hypotheses for low mtDNA diversity, next-generation sequencing (454 and Illumina) was used to sequence mitogenomes for 17 Pacific Ocean sperm whale samples, with other cetacean mitogenomes compiled from the literature. Using these mitogenomes, no evidence of slow substitution rates were found in the mtDNA CR or protein-coding genes of the mitogenome that could explain the low diversity. In addition, the mtDNA CR had the highest diversity of the entire mitogenome and showed genealogical patterns concordant with the rest of the mitogenome. This discounts mtDNA CR-specific constraints as the cause of low mtDNA CR diversity. To investigate the remaining hypotheses of a selective sweep, population bottleneck or expansion, 8 nuclear loci (~12,000 bp) were sequenced for 22 sperm whales (Pacific and Gulf of Mexico), and compared to 10 New Zealand pygmy sperm whales (Kogia breviceps). The results were inconsistent with a selective sweep and showed instead low diversity across both mtDNA and nuclear DNA, in comparison to the higher levels of genetic diversity in the pygmy sperm whale and other cetacean species. Demographic reconstructions showed the sperm whale to have had a stable, but small, population size for much of historical time. This suggests a recent population expansion is responsible for the low mtDNA (and nuclear DNA) diversity in the sperm whale. The inferred timing of the expansion corresponds with expansions in squid species (the primary prey of the sperm whale), and explains shared mtDNA haplotypes between oceans. Since this expansion, the marked philopatry shown by female sperm whales at various hierarchical levels ranging from social groups (e.g. lenient matrilineality) to broader geographic scales, has led to maternally-mediated genetic drift driving striking differences in mtDNA haplotype frequencies between social groups, regions, and oceans. 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