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• 1. [Article] Avian population trends within the evolving agricultural landscape of the eastern and central United States

  State-level Breeding Bird Survey (1980-1998) and U.S. Department of Agriculture statistics were used to test the hypothesis that changes in agricultural land use within the eastern and central U.S. have ...

  Citation × Citation Citation Abstract Copy Title: Avian population trends within the evolving agricultural landscape of the eastern and central United States Author: Murphy, Michael T. Year: 2003 State-level Breeding Bird Survey (1980-1998) and U.S. Department of Agriculture statistics were used to test the hypothesis that changes in agricultural land use within the eastern and central U.S. have driven population trends of grassland and shrub habitat birds over the past two decades. The degree to which population trends differed between grassland and shrub habitats was evaluated with respect to migratory and nesting behavior. Grassland birds declined significantly between 1980 and 1999, but, on average, shrub habitat species did not. Grassland-breeding, long-distance migrants exhibited the strongest negative trends. Most species (78%; n = 63) exhibited at least one significant association between population trends and changes in agricultural land use, and in most, land use "explained" 25-30% of the variation in population trends among states. Changes in the farmland landscape accounted for more of the interstate variability of population trends of short-distance migrants than of both long-distance migrants and residents, and that variability was greater in grassland than shrub species. Declines in the area of rangeland and cover crops were followed by population declines and increases, respectively, by many species. Increases of land in the Conservation Reserve Program had negative associations with population trends of some shrub species. The results indicate that grassland birds have declined strongly over the past two decades, and that regardless of migratory behavior or nesting habits, avian population trends are linked strongly to changes in agricultural land use within North America. Title: Avian population trends within the evolving agricultural landscape of the eastern and central United States Author: Murphy, Michael T. Year: 2003 State-level Breeding Bird Survey (1980-1998) and U.S. Department of Agriculture statistics were used to test the hypothesis that changes in agricultural land use within the eastern and central U.S. have driven population trends of grassland and shrub habitat birds over the past two decades. The degree to which population trends differed between grassland and shrub habitats was evaluated with respect to migratory and nesting behavior. Grassland birds declined significantly between 1980 and 1999, but, on average, shrub habitat species did not. Grassland-breeding, long-distance migrants exhibited the strongest negative trends. Most species (78%; n = 63) exhibited at least one significant association between population trends and changes in agricultural land use, and in most, land use "explained" 25-30% of the variation in population trends among states. Changes in the farmland landscape accounted for more of the interstate variability of population trends of short-distance migrants than of both long-distance migrants and residents, and that variability was greater in grassland than shrub species. Declines in the area of rangeland and cover crops were followed by population declines and increases, respectively, by many species. Increases of land in the Conservation Reserve Program had negative associations with population trends of some shrub species. The results indicate that grassland birds have declined strongly over the past two decades, and that regardless of migratory behavior or nesting habits, avian population trends are linked strongly to changes in agricultural land use within North America. Close

• 2. [Article] Demography of a Ground Nesting Bird in an Urban System: Are Populations Self-Sustaining?

  Urbanization poses threats to earth’s biota, and retention of remnant native habitat in protected areas within expanding urban boundaries may help alleviate threats to wildlife. However, it is unclear ...

  Citation × Citation Citation Abstract Copy Title: Demography of a Ground Nesting Bird in an Urban System: Are Populations Self-Sustaining? Author: Bartos Smith, Sarah, McKay, Jenny E., Richardson, Jennifer K., Shipley, Amy A., Murphy, Michael T. Year: 2016 Urbanization poses threats to earth’s biota, and retention of remnant native habitat in protected areas within expanding urban boundaries may help alleviate threats to wildlife. However, it is unclear for nearly all nonsynanthropic (i.e., not benefiting from an association with humans) species whether vital rates in urban habitats can sustain populations or if populations persist only through immigration from outside the urban boundary. We conducted a three-year study of spotted towhees (Aves: Pipilo maculatus) breeding in four undeveloped parks in Portland, OR, USA, to measure park-specific seasonal reproductive output (F) and annual adult survival (SA). We developed a stochastic model that combined F and SA with an estimate of first-year survival to measure population growth rate (λ) in all parks assumed to be closed to immigration. F differed among parks but SA did not. Relatively high F was possible because many pairs raised >1 brood/season. When combined with empirical estimates of survival through the 30-day period of post-fledging parental care (SD = 0.645), only 2 of 4 parks were self-sustaining (i.e., λ > 1.0). However, SD reflected substantial loss of fledglings to domestic cats (Felis catus). Assuming no loss to cats and either partial compensatory or additive mortality of fledglings substantially improved prospects of population persistence for declining (sink) populations. Moreover, allowing low levels of immigration to sinks reversed population declines in most parks even when vital rates were insufficient to maintain populations. Our results suggest that nonsynanthropic bird species can persist in urban landscapes, but also that offspring mortality in the post-fledging period may be a critical determinant of population viability. Title: Demography of a Ground Nesting Bird in an Urban System: Are Populations Self-Sustaining? Author: Bartos Smith, Sarah, McKay, Jenny E., Richardson, Jennifer K., Shipley, Amy A., Murphy, Michael T. Year: 2016 Urbanization poses threats to earth’s biota, and retention of remnant native habitat in protected areas within expanding urban boundaries may help alleviate threats to wildlife. However, it is unclear for nearly all nonsynanthropic (i.e., not benefiting from an association with humans) species whether vital rates in urban habitats can sustain populations or if populations persist only through immigration from outside the urban boundary. We conducted a three-year study of spotted towhees (Aves: Pipilo maculatus) breeding in four undeveloped parks in Portland, OR, USA, to measure park-specific seasonal reproductive output (F) and annual adult survival (SA). We developed a stochastic model that combined F and SA with an estimate of first-year survival to measure population growth rate (λ) in all parks assumed to be closed to immigration. F differed among parks but SA did not. Relatively high F was possible because many pairs raised >1 brood/season. When combined with empirical estimates of survival through the 30-day period of post-fledging parental care (SD = 0.645), only 2 of 4 parks were self-sustaining (i.e., λ > 1.0). However, SD reflected substantial loss of fledglings to domestic cats (Felis catus). Assuming no loss to cats and either partial compensatory or additive mortality of fledglings substantially improved prospects of population persistence for declining (sink) populations. Moreover, allowing low levels of immigration to sinks reversed population declines in most parks even when vital rates were insufficient to maintain populations. Our results suggest that nonsynanthropic bird species can persist in urban landscapes, but also that offspring mortality in the post-fledging period may be a critical determinant of population viability. Close

• 3. [Article] Stranding Mortality Patterns in California Sea Lions and Steller Sea Lions in Oregon and Southern Washington, 2006 to 2014

  As changing ocean conditions lead to declining fish stocks and movement of forage fish, sea lions on the Oregon coast are subject to the pressures of declining prey availability and increasing conflicts ...

  Citation × Citation Citation Abstract Copy Title: Stranding Mortality Patterns in California Sea Lions and Steller Sea Lions in Oregon and Southern Washington, 2006 to 2014 Author: Lee, Kessina Year: 2016 As changing ocean conditions lead to declining fish stocks and movement of forage fish, sea lions on the Oregon coast are subject to the pressures of declining prey availability and increasing conflicts with commercial and recreational fisheries. An analysis of strandings of California sea lions, Zalophus californianus, and Steller sea lions, Eumetopias jubatus, from 2006 to 2014, included cause of death, changing ocean conditions, and anthropogenic activity. Causes of death included disease, injury, and human interaction, such as gunshot wounds, fisheries net entanglements and boat strikes. Oregon and Washington strandings of California sea lions are primarily adult and subadult males that migrate north from California rookeries, while Steller sea lions are year-round residents and strandings are comprised of males and females of all ages. While the California sea lion population is currently at or near carrying capacity, the Eastern Pacific population of Steller sea lions was designated as Threatened under the Endangered Species Act until October 2013. Understanding impacts to these two pinniped species is vital to implementing effective management and conservation policies. Oregon and southern Washington strandings of California sea lions and Steller sea lions from 2006 to 2014 were analyzed spatially using the geographic information system (GIS), and temporally to identify possible correlations with prey availability and human interaction. Strandings were found to follow seasonal patterns from year to year: Steller sea lion strandings were highest from May to July, California sea lions peaked in September, October, and November. There was a correlation between significantly high numbers of strandings and the three largest commercial fisheries in Oregon: Chinook salmon, Coho salmon, and Dungeness crab. This analysis provides a format for continuing to monitor primary ecological and anthropogenic drivers of pinniped mortality in Oregon and southern Washington. Title: Stranding Mortality Patterns in California Sea Lions and Steller Sea Lions in Oregon and Southern Washington, 2006 to 2014 Author: Lee, Kessina Year: 2016 As changing ocean conditions lead to declining fish stocks and movement of forage fish, sea lions on the Oregon coast are subject to the pressures of declining prey availability and increasing conflicts with commercial and recreational fisheries. An analysis of strandings of California sea lions, Zalophus californianus, and Steller sea lions, Eumetopias jubatus, from 2006 to 2014, included cause of death, changing ocean conditions, and anthropogenic activity. Causes of death included disease, injury, and human interaction, such as gunshot wounds, fisheries net entanglements and boat strikes. Oregon and Washington strandings of California sea lions are primarily adult and subadult males that migrate north from California rookeries, while Steller sea lions are year-round residents and strandings are comprised of males and females of all ages. While the California sea lion population is currently at or near carrying capacity, the Eastern Pacific population of Steller sea lions was designated as Threatened under the Endangered Species Act until October 2013. Understanding impacts to these two pinniped species is vital to implementing effective management and conservation policies. Oregon and southern Washington strandings of California sea lions and Steller sea lions from 2006 to 2014 were analyzed spatially using the geographic information system (GIS), and temporally to identify possible correlations with prey availability and human interaction. Strandings were found to follow seasonal patterns from year to year: Steller sea lion strandings were highest from May to July, California sea lions peaked in September, October, and November. There was a correlation between significantly high numbers of strandings and the three largest commercial fisheries in Oregon: Chinook salmon, Coho salmon, and Dungeness crab. This analysis provides a format for continuing to monitor primary ecological and anthropogenic drivers of pinniped mortality in Oregon and southern Washington. Close

• 4. [Article] The Impact of Weather on Kingbird Foraging Behavior

  Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior ...

  Citation × Citation Citation Abstract Copy Title: The Impact of Weather on Kingbird Foraging Behavior Author: Murphy, Michael T. Year: 1987 Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats). Title: The Impact of Weather on Kingbird Foraging Behavior Author: Murphy, Michael T. Year: 1987 Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats). Close

• 5. [Article] Phenotypic and Mutational Consequences of Mitochondrial ETC Genetic Damage

  Genetic mutation is the ultimate source of new phenotypic variation in populations. The importance of mutation cannot be understated, and constitutes a significant evolutionary force. Although single mutations ...

  Citation × Citation Citation Abstract Copy Title: Phenotypic and Mutational Consequences of Mitochondrial ETC Genetic Damage Author: Lue, Michael James Year: 2015 Genetic mutation is the ultimate source of new phenotypic variation in populations. The importance of mutation cannot be understated, and constitutes a significant evolutionary force. Although single mutations may have little to no impact on organismal performance or fitness, when multiplied across the total number of potential sites within the genome, mutation can have a large impact. Accurate measurement of the rates, molecular mechanisms, and distributions of effects of mutations are critical for many applications of evolutionary theory. Despite the importance of both deleterious and beneficial mutations, their genome-wide patterns and phenotypic consequences are poorly understood when considering the mitochondrial genome. Mitochondria are organelles that are essential for eukaryotic life. They contain their own genome and generate bioenergy (ATP) necessary to sustain life via the electron transport chain (ETC). Because of their role in eukaryotic physiology, understanding how mitochondrial genetic and phenotypic variation can impact populations and evolutionary outcomes is essential. Past studies have implicated DNA-damaging oxidative stress as a source of mutations within somatic tissue, but there is a gap in knowledge regarding its role in heritable damage within the germ line. In this thesis, I aimed to test this possibility by characterizing the phenotypic and mutational consequences of high intracellular ROS levels caused by mitochondrial ETC genetic damage. I performed experiments using Caenorhabditis elegans ETC mutant, gas-1, and mutation-accumulation (MA) lines generated from this ancestral genotype. I quantified organismal fitness (fecundity and longevity), reactive oxygen species (ROS) levels, mitochondrial membrane potential (delta psi m), and ATP levels in these lines, and compared the results to those from a set of wildtype control lines. I begin with a general introduction to the hypothesis and the C. elegans system in Chapter I. In Chapter II, I report the findings from this work. In short, I found that while gas-1 MA lines began the experiment with low lifetime fecundity in comparison to the wildtype strain, their fecundity showed no further decline as expected, and even exhibited higher fecundity levels on days 3-5 of reproduction relative to the gas-1 progenitor. The gas-1 progenitor exhibited higher rates of ROS compared to wildtype, whereas the MA lines reverted back to wildtype levels; a similar pattern was observed for delta psi m, while ATP levels were low in the gas-1 progenitor and remained low in the MA lines. I interpret these findings in light of high-throughput sequencing results from these lines showing that, while nuclear and mitochondrial DNA mutation rates were equal to wildtype in these lines, the genomic pattern of mutation was highly nonrandom and indicative of selection for beneficial or compensatory sequence changes. Because ROS levels declined to wildtype in the evolved (MA), this study was unable to address whether ROS is a major contributor to heritable mutation in this system. I hypothesize that, in addition to their putatively compensatory genetic changes, gas-1 lineages experienced physiological compensation allowing them to survive, and that this was associated with a "slow living" phenotype. In Chapter III, I summarize general conclusions and implications of this study and end by providing suggestions for further study. Title: Phenotypic and Mutational Consequences of Mitochondrial ETC Genetic Damage Author: Lue, Michael James Year: 2015 Genetic mutation is the ultimate source of new phenotypic variation in populations. The importance of mutation cannot be understated, and constitutes a significant evolutionary force. Although single mutations may have little to no impact on organismal performance or fitness, when multiplied across the total number of potential sites within the genome, mutation can have a large impact. Accurate measurement of the rates, molecular mechanisms, and distributions of effects of mutations are critical for many applications of evolutionary theory. Despite the importance of both deleterious and beneficial mutations, their genome-wide patterns and phenotypic consequences are poorly understood when considering the mitochondrial genome. Mitochondria are organelles that are essential for eukaryotic life. They contain their own genome and generate bioenergy (ATP) necessary to sustain life via the electron transport chain (ETC). Because of their role in eukaryotic physiology, understanding how mitochondrial genetic and phenotypic variation can impact populations and evolutionary outcomes is essential. Past studies have implicated DNA-damaging oxidative stress as a source of mutations within somatic tissue, but there is a gap in knowledge regarding its role in heritable damage within the germ line. In this thesis, I aimed to test this possibility by characterizing the phenotypic and mutational consequences of high intracellular ROS levels caused by mitochondrial ETC genetic damage. I performed experiments using Caenorhabditis elegans ETC mutant, gas-1, and mutation-accumulation (MA) lines generated from this ancestral genotype. I quantified organismal fitness (fecundity and longevity), reactive oxygen species (ROS) levels, mitochondrial membrane potential (delta psi m), and ATP levels in these lines, and compared the results to those from a set of wildtype control lines. I begin with a general introduction to the hypothesis and the C. elegans system in Chapter I. In Chapter II, I report the findings from this work. In short, I found that while gas-1 MA lines began the experiment with low lifetime fecundity in comparison to the wildtype strain, their fecundity showed no further decline as expected, and even exhibited higher fecundity levels on days 3-5 of reproduction relative to the gas-1 progenitor. The gas-1 progenitor exhibited higher rates of ROS compared to wildtype, whereas the MA lines reverted back to wildtype levels; a similar pattern was observed for delta psi m, while ATP levels were low in the gas-1 progenitor and remained low in the MA lines. I interpret these findings in light of high-throughput sequencing results from these lines showing that, while nuclear and mitochondrial DNA mutation rates were equal to wildtype in these lines, the genomic pattern of mutation was highly nonrandom and indicative of selection for beneficial or compensatory sequence changes. Because ROS levels declined to wildtype in the evolved (MA), this study was unable to address whether ROS is a major contributor to heritable mutation in this system. I hypothesize that, in addition to their putatively compensatory genetic changes, gas-1 lineages experienced physiological compensation allowing them to survive, and that this was associated with a "slow living" phenotype. In Chapter III, I summarize general conclusions and implications of this study and end by providing suggestions for further study. Close

• 6. [Article] Quantifying the Impacts of a Novel Predator: The Distinctive Case of the Oregon Spotted Frog (<i>Rana pretiosa</i>) and the Invasive American Bullfrog (<i>Rana (Aquarana) catesbeiana</i>)

  The decline of the Oregon Spotted Frog (Rana pretiosa), a Pacific Northwest endemic now federally listed as threatened, has been attributed to several aspects of ecosystem alteration, primarily habitat ...

  Citation × Citation Citation Abstract Copy Title: Quantifying the Impacts of a Novel Predator: The Distinctive Case of the Oregon Spotted Frog (<i>Rana pretiosa</i>) and the Invasive American Bullfrog (<i>Rana (Aquarana) catesbeiana</i>) Author: Tidwell, Kyle Scott Year: 2017 The decline of the Oregon Spotted Frog (Rana pretiosa), a Pacific Northwest endemic now federally listed as threatened, has been attributed to several aspects of ecosystem alteration, primarily habitat degradation and loss. The introduced American Bullfrog (Rana (Aquarana) catesbeiana) has been widely implicated in those declines, but the basis of that contention has been difficult to characterize. The bullfrog occurring at every site of recent Oregon Spotted Frog extirpation has focused concern about its impact. Here, I present a suite of interconnected studies that examine the behavioral ecology of both species to better understand the potential for bullfrog-mediated Oregon Spotted Frog extirpation. I quantified Oregon Spotted Frog anti-predator behavior from the only known population successfully co-occurring with bullfrogs (Conboy Lake) and a population devoid of bullfrog impact (Big Marsh), and compared these behaviors to the predatory traits of the bullfrog. The initial study revealed that captive-reared individuals from the Oregon Spotted Frog population that has successfully co-occurred with bullfrogs respond faster to a predatory stimulus (measured as latency to response) than Oregon Spotted Frogs from a population not to exposed to bullfrogs. Subsequent field investigations of the approach distance allowed by a predator stimulus before taking evasive action (termed the flight initiation distance: FID) conducted with the Oregon Spotted Frog population co-occurring with bullfrogs first demonstrated that FID of recently metamorphosed bullfrogs is consistently greater than that of recently metamorphosed Oregon Spotted Frogs. Further, examination of FID across all post-metamorphic age classes of Oregon Spotted Frogs revealed that older frogs do not allow as close approach as recently metamorphosed Oregon Spotted Frogs. This age class shift in FID did not occur in the Oregon Spotted Frog population not exposed to bullfrogs. In the latter population, FID did not differ among age classes. Since the bullfrog might be driving this age-based change in anti-predator behavior, I explored the variation in strike distance of bullfrogs from the site of co-occurrence in both the field and laboratory to determine the extent of overlap with Oregon Spotted Frog FID. I found that the bullfrog strike distance significantly overlaps the FID of all ages of Oregon Spotted Frogs from the bullfrog-free site but only that of youngest (recently metamorphosed) frogs at the site of co-occurrence. Older Oregon Spotted Frogs from the site of co-occurrence generally escaped at distances greater than the strike distance of bullfrogs. I also collected > 880 bullfrogs from the site of co-occurrence and analyzed the stomach contents to assess their dietary trends. I found that bullfrogs consume Oregon Spotted Frogs at the site, but do not eat the larger (older) frogs. Moreover, the body size ratio between Oregon Spotted Frogs as prey and bullfrogs as predators suggests that nearly all of the adult size distribution of bullfrogs at Conboy would be incapable of preying on adult Oregon Spotted Frogs. Collectively, these studies strongly suggest that bullfrogs have altered the escape behavior of Oregon Spotted Frogs at Conboy Lake and that most adult Oregon Spotted Frogs at Conboy may have a size-based release from predation by bullfrogs. Implicit in this finding is that bullfrogs may pose a real threat via predation to other Oregon Spotted Frog populations with which they might come into contact where the distribution of bullfrog body sizes differ substantially from that at Conboy Lake. Title: Quantifying the Impacts of a Novel Predator: The Distinctive Case of the Oregon Spotted Frog (<i>Rana pretiosa</i>) and the Invasive American Bullfrog (<i>Rana (Aquarana) catesbeiana</i>) Author: Tidwell, Kyle Scott Year: 2017 The decline of the Oregon Spotted Frog (Rana pretiosa), a Pacific Northwest endemic now federally listed as threatened, has been attributed to several aspects of ecosystem alteration, primarily habitat degradation and loss. The introduced American Bullfrog (Rana (Aquarana) catesbeiana) has been widely implicated in those declines, but the basis of that contention has been difficult to characterize. The bullfrog occurring at every site of recent Oregon Spotted Frog extirpation has focused concern about its impact. Here, I present a suite of interconnected studies that examine the behavioral ecology of both species to better understand the potential for bullfrog-mediated Oregon Spotted Frog extirpation. I quantified Oregon Spotted Frog anti-predator behavior from the only known population successfully co-occurring with bullfrogs (Conboy Lake) and a population devoid of bullfrog impact (Big Marsh), and compared these behaviors to the predatory traits of the bullfrog. The initial study revealed that captive-reared individuals from the Oregon Spotted Frog population that has successfully co-occurred with bullfrogs respond faster to a predatory stimulus (measured as latency to response) than Oregon Spotted Frogs from a population not to exposed to bullfrogs. Subsequent field investigations of the approach distance allowed by a predator stimulus before taking evasive action (termed the flight initiation distance: FID) conducted with the Oregon Spotted Frog population co-occurring with bullfrogs first demonstrated that FID of recently metamorphosed bullfrogs is consistently greater than that of recently metamorphosed Oregon Spotted Frogs. Further, examination of FID across all post-metamorphic age classes of Oregon Spotted Frogs revealed that older frogs do not allow as close approach as recently metamorphosed Oregon Spotted Frogs. This age class shift in FID did not occur in the Oregon Spotted Frog population not exposed to bullfrogs. In the latter population, FID did not differ among age classes. Since the bullfrog might be driving this age-based change in anti-predator behavior, I explored the variation in strike distance of bullfrogs from the site of co-occurrence in both the field and laboratory to determine the extent of overlap with Oregon Spotted Frog FID. I found that the bullfrog strike distance significantly overlaps the FID of all ages of Oregon Spotted Frogs from the bullfrog-free site but only that of youngest (recently metamorphosed) frogs at the site of co-occurrence. Older Oregon Spotted Frogs from the site of co-occurrence generally escaped at distances greater than the strike distance of bullfrogs. I also collected > 880 bullfrogs from the site of co-occurrence and analyzed the stomach contents to assess their dietary trends. I found that bullfrogs consume Oregon Spotted Frogs at the site, but do not eat the larger (older) frogs. Moreover, the body size ratio between Oregon Spotted Frogs as prey and bullfrogs as predators suggests that nearly all of the adult size distribution of bullfrogs at Conboy would be incapable of preying on adult Oregon Spotted Frogs. Collectively, these studies strongly suggest that bullfrogs have altered the escape behavior of Oregon Spotted Frogs at Conboy Lake and that most adult Oregon Spotted Frogs at Conboy may have a size-based release from predation by bullfrogs. Implicit in this finding is that bullfrogs may pose a real threat via predation to other Oregon Spotted Frog populations with which they might come into contact where the distribution of bullfrog body sizes differ substantially from that at Conboy Lake. Close

• 7. [Article] Body Size, Nest Predation, and Reproductive Patterns in Brown Thrashers and Other Mimids

  We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. ...

  Citation × Citation Citation Abstract Copy Title: Body Size, Nest Predation, and Reproductive Patterns in Brown Thrashers and Other Mimids Author: Murphy, Michael T., Fleischer, Robert C. Year: 1986 We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. Brown Thrashers produced clutches of 3 to 6 eggs, but clutches of 4 predominated. Most pairs raised 2 broods per year. Incubation required between 13 and 14 days, and hatching was usually asynchronous. Though sample size was small, asynchrony appeared to increase in frequency towards the end of the breeding season. Nestlings grew rapidly, and in 10 days or less most pre-fledgingg rowthw as completed. Young fledgedn ormallya t 11 days of age at 65% of aduli weight, but with the tarsi near adult size. Nestlings starved in 27% of nests, but predators were responsible for most nest failures. Overall nest success was 43%. Brown Thrashers are typical of other temperate-zone mimids. Modal clutch sizes are of either 3 or 4 eggs and all species are multi-brooded. Mimids from the southwestern United States and Mexico lay normally 3 egg clutches, but elsewhere 4 eggs are most common. Incubation length and nestling growth rate vary significantly with adult weight, but on average, incubation is 3 days shorter and nestlings grow 36% faster than predicted. Relative incubation length and relative fledging weight both declined significantly with adult weight, whereas daily nest mortality rate increased significantly with adult size. Although our data are consistent with the hypothesis that heavy nest predation has favored rapid nestling growth and completion of development outside of the nest, rapid growth may also function in brood reduction. Present data are insufficient to exclude conclusively either factor in the evolution of rapid development in mimids. Title: Body Size, Nest Predation, and Reproductive Patterns in Brown Thrashers and Other Mimids Author: Murphy, Michael T., Fleischer, Robert C. Year: 1986 We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. Brown Thrashers produced clutches of 3 to 6 eggs, but clutches of 4 predominated. Most pairs raised 2 broods per year. Incubation required between 13 and 14 days, and hatching was usually asynchronous. Though sample size was small, asynchrony appeared to increase in frequency towards the end of the breeding season. Nestlings grew rapidly, and in 10 days or less most pre-fledgingg rowthw as completed. Young fledgedn ormallya t 11 days of age at 65% of aduli weight, but with the tarsi near adult size. Nestlings starved in 27% of nests, but predators were responsible for most nest failures. Overall nest success was 43%. Brown Thrashers are typical of other temperate-zone mimids. Modal clutch sizes are of either 3 or 4 eggs and all species are multi-brooded. Mimids from the southwestern United States and Mexico lay normally 3 egg clutches, but elsewhere 4 eggs are most common. Incubation length and nestling growth rate vary significantly with adult weight, but on average, incubation is 3 days shorter and nestlings grow 36% faster than predicted. Relative incubation length and relative fledging weight both declined significantly with adult weight, whereas daily nest mortality rate increased significantly with adult size. Although our data are consistent with the hypothesis that heavy nest predation has favored rapid nestling growth and completion of development outside of the nest, rapid growth may also function in brood reduction. Present data are insufficient to exclude conclusively either factor in the evolution of rapid development in mimids. Close

• 8. [Article] Causes and Consequences of Mitochondrial Variation in Caenorhabditid Nematodes

  Mitochondria are dynamic organelles that harbor their own stream-lined genome and generate much of the ATP necessary to sustain eukaryotic life via an electron transport chain (ETC). Because of the central ...

  Citation × Citation Citation Abstract Copy Title: Causes and Consequences of Mitochondrial Variation in Caenorhabditid Nematodes Author: Hicks, Kiley Ann Year: 2012 Mitochondria are dynamic organelles that harbor their own stream-lined genome and generate much of the ATP necessary to sustain eukaryotic life via an electron transport chain (ETC). Because of the central role for mitochondria in organismal physiology, mitochondrial genetic and phenotypic variation can alter organismal fitness and affect population genetic and evolutionary outcomes. Despite the far-reaching relevance of mitochondria to evolutionary processes and human health, we lack a basic understanding of the causes and consequences of mitochondrial genetic and phenotypic variation. In this thesis, I quantified mitochondrial reactive oxygen species (ROS), membrane potential (δΨM), and mitochondrial morphological traits within Caenorhabditis briggsae natural isolates and mutation-accumulation (MA) lines of both C. briggsae and Caenorhabditis elegans. Substantial natural variation was discovered for most mitochondrial form and function traits measured for a set of C. briggsae isolates known to harbor mitochondrial DNA structural variation in the form of a heteroplasmic nad5 gene deletion (nad5δ) that correlates negatively with organismal fitness. Most among-isolate phenotypic variation could be accounted for by phylogeographic clade membership rather than nad5δ level. Analysis of mitochondrial-nuclear hybrid strains provided support for both mtDNA and nuclear genetic variation as drivers of natural mitochondrial phenotype variation. An MA experimental approach revealed that average levels of both ROS and nad5δ heteroplasmy evolved in remarkably linear ways in C. briggsae maintained under extreme inbreeding. In particular, among C. briggsae isolates prone to acquiring the nad5δ deletion, nad5δ level increased to a plateau of ~50% during successive generations of MA treatment. Conversely, mitochondrial ROS level increased or declined in a strain-specific fashion, which also meant that the relationship between ROS and nad5δ was strain-specific. Further, all lines generated from the isolate with the highest starting level of nad5δ heteroplasmy went extinct prior to generation 20 of MA treatment. Patterns of among-line variance in ROS level were also strain-specific but generally did not conform to the canonical pattern of increasing among-line variance expected for MA experiments. MA lines of C. elegans that had previously been subjected to whole-genome sequencing were found to vary significantly in ROS levels but not in 8-oxo-dG content. Despite a significant positive correlation between 8-oxo-dG and ROS levels, no relationship between oxidative stress measures and base substitution rate or G-to-T transversion rate was revealed. Finally, analysis of patterns of phenotypic correlation for a suite of 24 mitochondrial traits measured in C. briggsae natural isolates support a role for ΔΨM in shaping mitochondrial dynamics, but no such role for mitochondrial ROS. Further, our study suggests a novel model of mitochondrial population dynamics dependent upon cellular environmental context and with implications for mitochondrial genome integrity. This work identifies extensive natural variation and capacity for evolution in organellar traits within multicellular eukaryotic species, with a central role for δΨM in mitochondrial dynamics that may have implications for evolutionary adaptation to thermal niches. Title: Causes and Consequences of Mitochondrial Variation in Caenorhabditid Nematodes Author: Hicks, Kiley Ann Year: 2012 Mitochondria are dynamic organelles that harbor their own stream-lined genome and generate much of the ATP necessary to sustain eukaryotic life via an electron transport chain (ETC). Because of the central role for mitochondria in organismal physiology, mitochondrial genetic and phenotypic variation can alter organismal fitness and affect population genetic and evolutionary outcomes. Despite the far-reaching relevance of mitochondria to evolutionary processes and human health, we lack a basic understanding of the causes and consequences of mitochondrial genetic and phenotypic variation. In this thesis, I quantified mitochondrial reactive oxygen species (ROS), membrane potential (δΨM), and mitochondrial morphological traits within Caenorhabditis briggsae natural isolates and mutation-accumulation (MA) lines of both C. briggsae and Caenorhabditis elegans. Substantial natural variation was discovered for most mitochondrial form and function traits measured for a set of C. briggsae isolates known to harbor mitochondrial DNA structural variation in the form of a heteroplasmic nad5 gene deletion (nad5δ) that correlates negatively with organismal fitness. Most among-isolate phenotypic variation could be accounted for by phylogeographic clade membership rather than nad5δ level. Analysis of mitochondrial-nuclear hybrid strains provided support for both mtDNA and nuclear genetic variation as drivers of natural mitochondrial phenotype variation. An MA experimental approach revealed that average levels of both ROS and nad5δ heteroplasmy evolved in remarkably linear ways in C. briggsae maintained under extreme inbreeding. In particular, among C. briggsae isolates prone to acquiring the nad5δ deletion, nad5δ level increased to a plateau of ~50% during successive generations of MA treatment. Conversely, mitochondrial ROS level increased or declined in a strain-specific fashion, which also meant that the relationship between ROS and nad5δ was strain-specific. Further, all lines generated from the isolate with the highest starting level of nad5δ heteroplasmy went extinct prior to generation 20 of MA treatment. Patterns of among-line variance in ROS level were also strain-specific but generally did not conform to the canonical pattern of increasing among-line variance expected for MA experiments. MA lines of C. elegans that had previously been subjected to whole-genome sequencing were found to vary significantly in ROS levels but not in 8-oxo-dG content. Despite a significant positive correlation between 8-oxo-dG and ROS levels, no relationship between oxidative stress measures and base substitution rate or G-to-T transversion rate was revealed. Finally, analysis of patterns of phenotypic correlation for a suite of 24 mitochondrial traits measured in C. briggsae natural isolates support a role for ΔΨM in shaping mitochondrial dynamics, but no such role for mitochondrial ROS. Further, our study suggests a novel model of mitochondrial population dynamics dependent upon cellular environmental context and with implications for mitochondrial genome integrity. This work identifies extensive natural variation and capacity for evolution in organellar traits within multicellular eukaryotic species, with a central role for δΨM in mitochondrial dynamics that may have implications for evolutionary adaptation to thermal niches. Close

• 9. [Article] Intestinal Microbiota Diversity of Pre-Smolt Steelhead (Oncorhynchus mykiss) Across Six Oregon and Washington Hatcheries

  The Pacific Northwest is known for its once-abundant wild salmonid populations that have been in decline for more than 50 years due to habitat destruction and commercial overexploitation. To compensate, ...

  Citation × Citation Citation Abstract Copy Title: Intestinal Microbiota Diversity of Pre-Smolt Steelhead (Oncorhynchus mykiss) Across Six Oregon and Washington Hatcheries Author: Yildirimer, Christina Carrell Year: 2017 The Pacific Northwest is known for its once-abundant wild salmonid populations that have been in decline for more than 50 years due to habitat destruction and commercial overexploitation. To compensate, federal and state agencies annually release hundreds of thousands of hatchery-reared fish into the wild. However, accumulating data indicate that hatchery fish have lower fitness in natural environments, and that hatchery rearing negatively influences return rates of anadromous salmonids. Recently, mounting evidence revealed that the richness and diversity of intestinal microbial species influence host health. We examined the gut microbiota of pre-migratory hatchery-reared steelhead (Oncorhynchus mykiss) to assess microbial community diversity. The Cascade Mountains serve as an allopatric border between two distinct clades of steelhead that show significant differences in genomic and mitochondrial diversity. We identified differences in core microbiota of hatchery-reared fish that correlate with this divergent phylogeographic distribution. Steelhead sampled from hatcheries east of the Cascades had overall greater core gut microbiota diversity. These differences were found despite similarities in diet and rearing conditions. In addition to taxonomic variation across the geographic divide, we identified significant differences in metabolic pathways using PICRUSt gene prediction software. Our analysis revealed significant enrichment of genes associated with lipid metabolism in the gut microbiome of western fish. 8 of 19 individual lipid metabolism pathways were more prominent in western populations. Lipids are a vital nutritional component for teleost species involved in migration and subsequent return for spawning in natal environments. We hypothesize that the observed differences in lipid metabolism across this phylogenetic divide results from an increased ability of eastern Cascade (O. m. gairdneri) fish to utilize lipids taken in via the diet. This increased absorption and utilization would make lipids less available for the intestinal microbiota of the eastern fish, as evidenced by the lower abundance of lipid metabolism genes in the east. Our research utilizes information from the microbiome to understand the phenotypic implications occurring in segregated populations of hatchery-reared steelhead, further confirming elements of coevolution between an organism and its internal environment. Title: Intestinal Microbiota Diversity of Pre-Smolt Steelhead (Oncorhynchus mykiss) Across Six Oregon and Washington Hatcheries Author: Yildirimer, Christina Carrell Year: 2017 The Pacific Northwest is known for its once-abundant wild salmonid populations that have been in decline for more than 50 years due to habitat destruction and commercial overexploitation. To compensate, federal and state agencies annually release hundreds of thousands of hatchery-reared fish into the wild. However, accumulating data indicate that hatchery fish have lower fitness in natural environments, and that hatchery rearing negatively influences return rates of anadromous salmonids. Recently, mounting evidence revealed that the richness and diversity of intestinal microbial species influence host health. We examined the gut microbiota of pre-migratory hatchery-reared steelhead (Oncorhynchus mykiss) to assess microbial community diversity. The Cascade Mountains serve as an allopatric border between two distinct clades of steelhead that show significant differences in genomic and mitochondrial diversity. We identified differences in core microbiota of hatchery-reared fish that correlate with this divergent phylogeographic distribution. Steelhead sampled from hatcheries east of the Cascades had overall greater core gut microbiota diversity. These differences were found despite similarities in diet and rearing conditions. In addition to taxonomic variation across the geographic divide, we identified significant differences in metabolic pathways using PICRUSt gene prediction software. Our analysis revealed significant enrichment of genes associated with lipid metabolism in the gut microbiome of western fish. 8 of 19 individual lipid metabolism pathways were more prominent in western populations. Lipids are a vital nutritional component for teleost species involved in migration and subsequent return for spawning in natal environments. We hypothesize that the observed differences in lipid metabolism across this phylogenetic divide results from an increased ability of eastern Cascade (O. m. gairdneri) fish to utilize lipids taken in via the diet. This increased absorption and utilization would make lipids less available for the intestinal microbiota of the eastern fish, as evidenced by the lower abundance of lipid metabolism genes in the east. Our research utilizes information from the microbiome to understand the phenotypic implications occurring in segregated populations of hatchery-reared steelhead, further confirming elements of coevolution between an organism and its internal environment. Close

• 10. [Article] Investigations of Larval Pacific Lamprey Entosphenus tridentatus Osmotic Stress Tolerance and Occurrence in a Tidally-Influenced Estuarine Stream

  Pacific lamprey is a culturally valuable species to indigenous people, and has significant ecological importance in freshwater and marine ecosystems. Over the past several decades, constrictions in range ...

  Citation × Citation Citation Abstract Copy Title: Investigations of Larval Pacific Lamprey Entosphenus tridentatus Osmotic Stress Tolerance and Occurrence in a Tidally-Influenced Estuarine Stream Author: Silver, Gregory Shell Year: 2015 Pacific lamprey is a culturally valuable species to indigenous people, and has significant ecological importance in freshwater and marine ecosystems. Over the past several decades, constrictions in range and reductions in Pacific lamprey abundance have been observed in Western North America, and may be indicators of range-wide declines. In the face of declining populations, the U.S. Fish and Wildlife Service has partnered with tribal, state, federal, and local entities to implement a regional Pacific lamprey conservation agreement aimed at reducing threats to Pacific lamprey and improving their habitats and population status. Research needs identified in the conservation agreement include assessing larval Pacific lamprey occupancy and distribution, habitat requirements, and the limiting factors of larval distribution in the freshwater ecosystem. As part of the effort to address these knowledge gaps, we investigated the potential for larval lampreys to occur in tidally-influenced estuarine environments. Research of this type may be valuable for future conservation, management or recovery efforts of Pacific lamprey throughout its range. We employed a two-phased approach, consisting of laboratory and field components to address our aims. We first conducted a series of controlled laboratory experiments to evaluate osmotic stress tolerance and osmoregulatory status of larval Pacific lamprey exposed to a range of (1) fixed salinity in various dilutions of saltwater and (2) oscillating salinity treatments designed to simulate tidal activity. Tolerance was assessed by monitoring and comparing survival of larvae in various treatments through 96 h. Osmoregulatory status was assessed by quantifying and comparing total body water content, plasma osmolality, and plasma cation (i.e., sodium) concentrations among larvae surviving various treatments. In fixed salinity experiments, 100% survival was observed in 0‰, 6‰, 8‰ and 10‰ through 96 h, while 0% survival was observed through 48 h in 12‰, 30 h in 15‰, and 12 h in 25‰ and 35‰. In oscillating salinity experiments, on the other hand, a significant increase in survival (100%) was observed through 96 h in treatments that oscillated between 12‰ and 0‰ (freshwater) at about 6 h intervals versus fixed 12‰ salinity experiments. A significant increase in survival also occurred in oscillating 15‰ treatments (60%) versus fixed 15‰ through 96 h. Linear regression analysis indicated higher environmental salinity in laboratory experiments was significantly related to increases in plasma osmolality and plasma sodium (the most abundant osmotically active plasma cation) concentrations, and concurrent decreases in total body water content among larvae that survived various treatments. Tidal oscillations in salinity appeared to temper the desiccating effects of salinity, as changes in body water content and sodium ion concentration were less abrupt than fixed salinity treatments. These results suggest larvae cannot osmoregulate in hyperosmotic environments, but are able to tolerate some fixed and oscillating hyperosmotic salinity exposure. Consequently, larvae may be able to occur in certain areas of estuaries, such as oligohaline habitats that are characterized by low levels of salinity. Experimental results were used, in part, to guide larval sampling in a tidally-influenced habitat. Occurrence of larval Pacific lamprey and Lampetra spp. (western brook and river lampreys) was subsequently investigated across a gradient of salinity in Ellsworth Creek (Pacific County, Washington) by electrofishing. Larval Pacific and Lampetra spp. were detected within an approximately 300 m long tidally-influenced segment of the study area. Salinity monitoring was conducted in six tidally-influenced reaches where larvae were detected for up to 14 d following electrofishing. Maximum tidal cycle salinity exceeded 15 ppt during 52% to 80% of tidal cycles within tidally-influenced reaches where larvae were detected. These results suggest potential for larval lamprey to occur in certain portions of tidal estuaries. However, long-term residence of larvae in tidally-influenced habitats and whether larvae are able to subsequently survive, grow, transform, and out-migrate is not known and requires further study. Given the potential for tidally-influenced habitats to be occupied by larvae, assessments of larval occurrence in other areas, such as the lower Columbia River, may be warranted. Knowledge of larval lamprey distribution in estuarine environments may be valuable for habitat restoration, and mitigating potential impacts from dredging and other human disturbances. Title: Investigations of Larval Pacific Lamprey Entosphenus tridentatus Osmotic Stress Tolerance and Occurrence in a Tidally-Influenced Estuarine Stream Author: Silver, Gregory Shell Year: 2015 Pacific lamprey is a culturally valuable species to indigenous people, and has significant ecological importance in freshwater and marine ecosystems. Over the past several decades, constrictions in range and reductions in Pacific lamprey abundance have been observed in Western North America, and may be indicators of range-wide declines. In the face of declining populations, the U.S. Fish and Wildlife Service has partnered with tribal, state, federal, and local entities to implement a regional Pacific lamprey conservation agreement aimed at reducing threats to Pacific lamprey and improving their habitats and population status. Research needs identified in the conservation agreement include assessing larval Pacific lamprey occupancy and distribution, habitat requirements, and the limiting factors of larval distribution in the freshwater ecosystem. As part of the effort to address these knowledge gaps, we investigated the potential for larval lampreys to occur in tidally-influenced estuarine environments. Research of this type may be valuable for future conservation, management or recovery efforts of Pacific lamprey throughout its range. We employed a two-phased approach, consisting of laboratory and field components to address our aims. We first conducted a series of controlled laboratory experiments to evaluate osmotic stress tolerance and osmoregulatory status of larval Pacific lamprey exposed to a range of (1) fixed salinity in various dilutions of saltwater and (2) oscillating salinity treatments designed to simulate tidal activity. Tolerance was assessed by monitoring and comparing survival of larvae in various treatments through 96 h. Osmoregulatory status was assessed by quantifying and comparing total body water content, plasma osmolality, and plasma cation (i.e., sodium) concentrations among larvae surviving various treatments. In fixed salinity experiments, 100% survival was observed in 0‰, 6‰, 8‰ and 10‰ through 96 h, while 0% survival was observed through 48 h in 12‰, 30 h in 15‰, and 12 h in 25‰ and 35‰. In oscillating salinity experiments, on the other hand, a significant increase in survival (100%) was observed through 96 h in treatments that oscillated between 12‰ and 0‰ (freshwater) at about 6 h intervals versus fixed 12‰ salinity experiments. A significant increase in survival also occurred in oscillating 15‰ treatments (60%) versus fixed 15‰ through 96 h. Linear regression analysis indicated higher environmental salinity in laboratory experiments was significantly related to increases in plasma osmolality and plasma sodium (the most abundant osmotically active plasma cation) concentrations, and concurrent decreases in total body water content among larvae that survived various treatments. Tidal oscillations in salinity appeared to temper the desiccating effects of salinity, as changes in body water content and sodium ion concentration were less abrupt than fixed salinity treatments. These results suggest larvae cannot osmoregulate in hyperosmotic environments, but are able to tolerate some fixed and oscillating hyperosmotic salinity exposure. Consequently, larvae may be able to occur in certain areas of estuaries, such as oligohaline habitats that are characterized by low levels of salinity. Experimental results were used, in part, to guide larval sampling in a tidally-influenced habitat. Occurrence of larval Pacific lamprey and Lampetra spp. (western brook and river lampreys) was subsequently investigated across a gradient of salinity in Ellsworth Creek (Pacific County, Washington) by electrofishing. Larval Pacific and Lampetra spp. were detected within an approximately 300 m long tidally-influenced segment of the study area. Salinity monitoring was conducted in six tidally-influenced reaches where larvae were detected for up to 14 d following electrofishing. Maximum tidal cycle salinity exceeded 15 ppt during 52% to 80% of tidal cycles within tidally-influenced reaches where larvae were detected. These results suggest potential for larval lamprey to occur in certain portions of tidal estuaries. However, long-term residence of larvae in tidally-influenced habitats and whether larvae are able to subsequently survive, grow, transform, and out-migrate is not known and requires further study. Given the potential for tidally-influenced habitats to be occupied by larvae, assessments of larval occurrence in other areas, such as the lower Columbia River, may be warranted. Knowledge of larval lamprey distribution in estuarine environments may be valuable for habitat restoration, and mitigating potential impacts from dredging and other human disturbances. Close