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• 251. [Article] Ecomorphology and Mating Behavior of Two Species of Night-stalking Tiger Beetles, Omus audouini and O. dejeanii

  Night-stalking tiger beetles (Cicindelinae: Omus) are among the least studied members of the highly diverse Carabid sub-family Cicindelinae, the tiger beetles. Despite populations of Omus being common ...

  Citation × Citation Citation Abstract Copy Title: Ecomorphology and Mating Behavior of Two Species of Night-stalking Tiger Beetles, Omus audouini and O. dejeanii Author: Richardson, Robert Kent Year: 2013 Night-stalking tiger beetles (Cicindelinae: Omus) are among the least studied members of the highly diverse Carabid sub-family Cicindelinae, the tiger beetles. Despite populations of Omus being common in the forest floor habitats of the west coast of North America and their conspicuous predatory role within terrestrial arthropod communities, little is known about the biology and ecology of Omus. Field studies showed that two species of Omus existed in the forested areas of Powell Butte Nature Park, Portland, Oregon, USA: Omus audouiniand O. dejeanii. The co-occurrence of sympatric, and likely syntopic, species allowed for a comparative approach in examining and analyzing previously unknown or unaddressed aspects of the biology of Omus. Both morphometric and behavioral analysis was used to address specific questions regarding niche partitioning and mating behaviors in the genus. On the basis of the competitive exclusion principle, I predicted that these closely related species with similar ecological requirements would experience selective pressure to minimize niche overlap and competitive pressures through morphological character displacement. In particular, the mandibles of male tiger beetles serve a dual role: one as tools for feeding-- including prey capture and prey processing--and another role as secondary sexual organs whereby the males use their mandibles to grasp the female and maintain amplexus. A geometric morphometric approach was used to evaluate and compare shape differences between the two species as well as identify trends of sexual dimorphism and species differences in context of prey base. Tiger beetles obligatorily engage in male-superior mounted mating behavior. Body size was used to first address trends of female-biased sexual size dimorphism within the Carabid subfamily Cicindelinae. Female tiger beetles may be expected to experience proportionally greater stress during mating among larger bodied than smaller bodied species and selection would favor increasingly pronounced female-biased sexual size dimorphism among larger-bodied species. The mating duration of Omuswas anecdotally reported as an order of magnitude greater than any other tiger beetle but has never been experimentally confirmed. I performed a series of pairings under laboratory setting to (1) establish a baseline of mating duration for the two species and test the effects of (2) time of day mating was initiated, (3) food deprivation and (4) operational sex ratio on mating duration. Morphometric analysis suggested niche partitioning existed between the two species due to an average body size scaling factor of x1.3 and an average mandible length scaling factor of x1.5, i.e. "Hutchinsonian Ratios"-- an observed minimum scaling threshold of niche differentiation seen in several natural predator populations. Similar minimum values were not seen between the sexes of either species suggesting an absence of sexual niche dimorphism. Geometric morphometric analysis of the mandibles revealed two distinct regions subject to selective adaptation: the distal region of the mandible (including the apical incisor) was consistently sexually dimorphic between the examined species while the proximal region involving the terebral teeth showed interspecific differences independent of sex and likely associated with prey processing, further supporting the hypothesis of niche partitioning between the two species but not necessarily between the sexes. The magnitude of sexual size dimorphism was found to be constant within Cicindelinae regardless of species body size. Behavioral analysis of mating established thatO. audouiniandO. dejeaniihave average (± SD) mating durations of 10.6 (± 1.8) and 29.4 (± 5.6) hours, respectively. Time of initiation of mating (whether morning or evening), food deprivation and operational sex ratio did not have any statistically significant effect on mating duration for either species. The absence of effect operational sex ratios on mating duration by suggests that mate guarding may not be a universal factor for all tiger beetles and, instead, syn- copulatory courtship, as opposed to pre- or post-copulatory courtship, as a female-choice reproductive mechanism may serve as a better explanation for the mating behaviors seen in Omus. Title: Ecomorphology and Mating Behavior of Two Species of Night-stalking Tiger Beetles, Omus audouini and O. dejeanii Author: Richardson, Robert Kent Year: 2013 Night-stalking tiger beetles (Cicindelinae: Omus) are among the least studied members of the highly diverse Carabid sub-family Cicindelinae, the tiger beetles. Despite populations of Omus being common in the forest floor habitats of the west coast of North America and their conspicuous predatory role within terrestrial arthropod communities, little is known about the biology and ecology of Omus. Field studies showed that two species of Omus existed in the forested areas of Powell Butte Nature Park, Portland, Oregon, USA: Omus audouiniand O. dejeanii. The co-occurrence of sympatric, and likely syntopic, species allowed for a comparative approach in examining and analyzing previously unknown or unaddressed aspects of the biology of Omus. Both morphometric and behavioral analysis was used to address specific questions regarding niche partitioning and mating behaviors in the genus. On the basis of the competitive exclusion principle, I predicted that these closely related species with similar ecological requirements would experience selective pressure to minimize niche overlap and competitive pressures through morphological character displacement. In particular, the mandibles of male tiger beetles serve a dual role: one as tools for feeding-- including prey capture and prey processing--and another role as secondary sexual organs whereby the males use their mandibles to grasp the female and maintain amplexus. A geometric morphometric approach was used to evaluate and compare shape differences between the two species as well as identify trends of sexual dimorphism and species differences in context of prey base. Tiger beetles obligatorily engage in male-superior mounted mating behavior. Body size was used to first address trends of female-biased sexual size dimorphism within the Carabid subfamily Cicindelinae. Female tiger beetles may be expected to experience proportionally greater stress during mating among larger bodied than smaller bodied species and selection would favor increasingly pronounced female-biased sexual size dimorphism among larger-bodied species. The mating duration of Omuswas anecdotally reported as an order of magnitude greater than any other tiger beetle but has never been experimentally confirmed. I performed a series of pairings under laboratory setting to (1) establish a baseline of mating duration for the two species and test the effects of (2) time of day mating was initiated, (3) food deprivation and (4) operational sex ratio on mating duration. Morphometric analysis suggested niche partitioning existed between the two species due to an average body size scaling factor of x1.3 and an average mandible length scaling factor of x1.5, i.e. "Hutchinsonian Ratios"-- an observed minimum scaling threshold of niche differentiation seen in several natural predator populations. Similar minimum values were not seen between the sexes of either species suggesting an absence of sexual niche dimorphism. Geometric morphometric analysis of the mandibles revealed two distinct regions subject to selective adaptation: the distal region of the mandible (including the apical incisor) was consistently sexually dimorphic between the examined species while the proximal region involving the terebral teeth showed interspecific differences independent of sex and likely associated with prey processing, further supporting the hypothesis of niche partitioning between the two species but not necessarily between the sexes. The magnitude of sexual size dimorphism was found to be constant within Cicindelinae regardless of species body size. Behavioral analysis of mating established thatO. audouiniandO. dejeaniihave average (± SD) mating durations of 10.6 (± 1.8) and 29.4 (± 5.6) hours, respectively. Time of initiation of mating (whether morning or evening), food deprivation and operational sex ratio did not have any statistically significant effect on mating duration for either species. The absence of effect operational sex ratios on mating duration by suggests that mate guarding may not be a universal factor for all tiger beetles and, instead, syn- copulatory courtship, as opposed to pre- or post-copulatory courtship, as a female-choice reproductive mechanism may serve as a better explanation for the mating behaviors seen in Omus. Close

• 252. [Article] Examination of Human Impacts on the Biodiversity and Ecology of Lichen and Moss Communities

  Globally, more than half of the world's population is living in urban areas and it is well accepted that human activities (e.g. climate warming, pollution, landscape homogenization) pose a multitude of ...

  Citation × Citation Citation Abstract Copy Title: Examination of Human Impacts on the Biodiversity and Ecology of Lichen and Moss Communities Author: Prather, Hannah Marie Year: 2017 Globally, more than half of the world's population is living in urban areas and it is well accepted that human activities (e.g. climate warming, pollution, landscape homogenization) pose a multitude of threats to ecosystems. Largely, human-related impacts on biodiversity will hold consequences for larger ecological processes and research looking into human impacts on sensitive epiphytic lichen and moss communities is an emerging area of research. While seemingly small, lichen and moss communities exist on nearly every terrestrial ecosystem on Earth and contribute to whole-system processes (e.g. hydrology, mineral cycling, food web energetics) worldwide. To further examine human impacts on epiphytic communities, I conducted three studies examining urbanization and climate warming effects on epiphytic lichen and moss biodiversity and ecology. In the first study I revisited a historic urban lichen community study to assess how urban lichen communities have responded to regional air quality changes occurring over the last nearly two decades. I further investigated, for the first time, the biodiversity of urban tree canopy-dwelling lichen communities in a native coniferous tree species, Pseudotsuga menziesii. I found that urban parks and forested areas harbor a species rich community of lichens epiphytes. Further, I found evidence for the distinct homogenization of urban epiphytic lichen communities, suggesting that expanding beyond simplistic measures of biodiversity to consider community composition and functional biodiversity may be necessary when assessing the ecology and potential ecosystem services of epiphyte communites within urbanizing landscapes. Next, I present the first tall tree canopy study across a regional gradient of urbanization near Portland, Oregon, USA. I found that tall tree canopy epiphyte communities change dramatically along gradients of increasing urbanization, most notably by the transitioning of species functional groups from sensitive, oligotrophic species to a dominance of urban-tolerant, eutrophic species. The implications these dramatic shifts in species composition have on essential PNW ecosystem processes, like N-fixation and canopy microclimate regulation, is still not well understood and is difficult to formally evaluate. However, I find strong evidence that native conifer trees in urban areas may provide a diversity of essential ecosystem services, including providing stratified habitat for epiphyte communities and their associated micro arthropod communities and the scavenging of atmospherically deposited nutrients. Future work is needed to understand how losses in canopy N fixation and species with large biomass (both lichens and bryophytes) will affect nutrient and hydrologic cycling in the PNW region, which continue to undergo rapid growth and urbanization. The final chapter investigates the impacts of passive warming by Open Top Chambers (OTCs) in moss-dominated ecosystems located on the Western Antarctic Peninsula, an area of increasing climate warming. I compared species-specific temperature effects, moss canopy morphology, sexual reproductive effort and invertebrate communities between OTC and control moss communities for two moss species, Polytrichastrum alpinum and Sanionia uncinata, that make up over 65% of the terrestrial vegetative cover in the area. I found distinct reproductive shifts in P. alpinum under passive warming compared to controls. Moss communities under warming also had substantially larger total invertebrate communities than those in control moss communities, and invertebrate communities were significantly affected by moss species and moss reproductive effort. Further, substantial species-specific thermal differences among contiguous patches of these dominant moss species were revealed. These results suggest that continued warming will differentially impact the reproductive output of Antarctic moss species and is likely to dramatically alter terrestrial ecosystems dynamics from the bottom up. This combined work provides a diverse contribution to the field of epiphyte ecology and biology by providing new insights on how human impacts will affect epiphyte lichen and moss communities across diverse ecosystems, in light of a rapidly changing planet. Title: Examination of Human Impacts on the Biodiversity and Ecology of Lichen and Moss Communities Author: Prather, Hannah Marie Year: 2017 Globally, more than half of the world's population is living in urban areas and it is well accepted that human activities (e.g. climate warming, pollution, landscape homogenization) pose a multitude of threats to ecosystems. Largely, human-related impacts on biodiversity will hold consequences for larger ecological processes and research looking into human impacts on sensitive epiphytic lichen and moss communities is an emerging area of research. While seemingly small, lichen and moss communities exist on nearly every terrestrial ecosystem on Earth and contribute to whole-system processes (e.g. hydrology, mineral cycling, food web energetics) worldwide. To further examine human impacts on epiphytic communities, I conducted three studies examining urbanization and climate warming effects on epiphytic lichen and moss biodiversity and ecology. In the first study I revisited a historic urban lichen community study to assess how urban lichen communities have responded to regional air quality changes occurring over the last nearly two decades. I further investigated, for the first time, the biodiversity of urban tree canopy-dwelling lichen communities in a native coniferous tree species, Pseudotsuga menziesii. I found that urban parks and forested areas harbor a species rich community of lichens epiphytes. Further, I found evidence for the distinct homogenization of urban epiphytic lichen communities, suggesting that expanding beyond simplistic measures of biodiversity to consider community composition and functional biodiversity may be necessary when assessing the ecology and potential ecosystem services of epiphyte communites within urbanizing landscapes. Next, I present the first tall tree canopy study across a regional gradient of urbanization near Portland, Oregon, USA. I found that tall tree canopy epiphyte communities change dramatically along gradients of increasing urbanization, most notably by the transitioning of species functional groups from sensitive, oligotrophic species to a dominance of urban-tolerant, eutrophic species. The implications these dramatic shifts in species composition have on essential PNW ecosystem processes, like N-fixation and canopy microclimate regulation, is still not well understood and is difficult to formally evaluate. However, I find strong evidence that native conifer trees in urban areas may provide a diversity of essential ecosystem services, including providing stratified habitat for epiphyte communities and their associated micro arthropod communities and the scavenging of atmospherically deposited nutrients. Future work is needed to understand how losses in canopy N fixation and species with large biomass (both lichens and bryophytes) will affect nutrient and hydrologic cycling in the PNW region, which continue to undergo rapid growth and urbanization. The final chapter investigates the impacts of passive warming by Open Top Chambers (OTCs) in moss-dominated ecosystems located on the Western Antarctic Peninsula, an area of increasing climate warming. I compared species-specific temperature effects, moss canopy morphology, sexual reproductive effort and invertebrate communities between OTC and control moss communities for two moss species, Polytrichastrum alpinum and Sanionia uncinata, that make up over 65% of the terrestrial vegetative cover in the area. I found distinct reproductive shifts in P. alpinum under passive warming compared to controls. Moss communities under warming also had substantially larger total invertebrate communities than those in control moss communities, and invertebrate communities were significantly affected by moss species and moss reproductive effort. Further, substantial species-specific thermal differences among contiguous patches of these dominant moss species were revealed. These results suggest that continued warming will differentially impact the reproductive output of Antarctic moss species and is likely to dramatically alter terrestrial ecosystems dynamics from the bottom up. This combined work provides a diverse contribution to the field of epiphyte ecology and biology by providing new insights on how human impacts will affect epiphyte lichen and moss communities across diverse ecosystems, in light of a rapidly changing planet. Close

• 253. [Article] Applying GPS and Accelerometers to the Study of African Savanna (Loxodonta africana) and Asian Elephant (Elephas maximus) Welfare in Zoos

  African savanna elephants (Loxodonta africana) and Asian elephants (Elephas maximus) are a focus of welfare research in zoos due to their high intelligence, complex social structure, and sheer size. Due ...

  Citation × Citation Citation Abstract Copy Title: Applying GPS and Accelerometers to the Study of African Savanna (Loxodonta africana) and Asian Elephant (Elephas maximus) Welfare in Zoos Author: Holdgate, Matthew Robert Year: 2015 African savanna elephants (Loxodonta africana) and Asian elephants (Elephas maximus) are a focus of welfare research in zoos due to their high intelligence, complex social structure, and sheer size. Due to these challenges, some argue that zoos are inherently incapable of providing appropriate care for elephants, while others believe that zoos can fulfill the needs of these species with improved husbandry. There is a general consensus from both within and outside of zoos, however, that zoos must improve their elephant programs or cease exhibiting these animals altogether. Now more than ever, applied research on zoo elephant welfare is needed to provide context for this debate. Researchers are interested in how far zoo elephants walk due to the potential health and welfare benefits of walking in these highly mobile species. Zoo researchers recently adopted GPS technology to study elephant walking, and preliminary evidence suggests that African elephants in large zoo exhibits walk distances that correspond with wild elephants under non-extreme conditions. However, data are limited from Asian elephants and from elephants in more typically-sized exhibits. In Chapter Two, I discuss important methodological considerations of utilizing GPS in a zoo environment, including an introduction to the technology, sources of error and mitigation, methods to improve GPS performance, and possible effects of GPS device attachment on animal behavior. This review shows GPS performance is adequate for tracking zoo elephant walking when proper methodological techniques are applied, and should serve as a useful reference for zoo researchers considering using GPS. In Chapter Three, I used GPS anklets to measure outdoor daily walking distance in 56 adult female African (n = 33) and Asian (n = 23) elephants housed in 30 zoos. I collected 259 days of data and found that elephants walked an average of 5.34 km/day with no significant difference between species. Multivariate regression models predicted that elephants with more dynamic feeding regimens (more diverse feeding types and frequencies; unscheduled feeding times) will walk more. Distance walked was also predicted to be higher in elephants that spend time in a greater number of different social groups. Distance walked was predicted to decline with age. Finally, I found a significant negative correlation between distance walked and nighttime space experience. The results of the analysis suggest that zoos that want to increase walking in their elephants need not rely solely on larger exhibits, but can increase walking by adding quality and complexity to exhibits. However, my results failed to establish a definitive link between walking distance and other validated measures of elephant welfare. Thus, the direct health and welfare benefits of walking in zoo elephants remain unresolved. Resting behaviors are an essential component of animal welfare, but have received little attention in zoological research. In Chapter Four, I used accelerometers in anklets to complete the first large-scale multi-species investigation of zoo elephant recumbence. I collected 344 days of data from 72 adult female African (n = 44) and Asian (n = 28) elephants at 40 zoos. I found that African elephants are recumbent an average of 2.14 hours/day, which is significantly less than Asian elephants at 3.22 hours/day. Multivariate regression models predicted that African elephant recumbence increases when they experience more space at night, and Asian elephant recumbence increases when they spend time housed alone. Both species showed a similar response to substrate, such that African elephants spending time on all-hard substrates are predicted to be recumbent less, while Asian elephants spending time on all-soft substrates are predicted to be recumbent more. The discovery that occasional non-recumbence is a common behavior in zoo elephants also introduces a new area of research that may have important animal welfare consequences. Finally, this study established that zoos should continue their efforts to replace hard substrate with soft substrate in order to provide zoo elephants with environments that facilitate recumbence. Overall, this work assessed walking and recumbence in zoo elephants, which will allow zoos to gauge the prevalence of these behaviors in their elephants as compared to the sub-population studied here. A variety of factors that are associated with these behaviors were also identified. With this information, zoos can prioritize modifications to their facilities and animal management programs to create an environment that encourages zoo elephants to express walking and recumbence behavior, should they choose to do so. This work is one component of the Elephant Welfare Project, the largest zoo animal welfare project ever undertaken, and is unprecedented in both scope and scale. The project was funded by the Institute of Museum and Library Services (IMLS), an independent, U.S., federal, grant-making agency that supports libraries, museums, and zoos. At the time of this writing, the first manuscripts from this project are being submitted to academic journals. These papers will describe the prevalence and distribution of a variety of elephant behaviors and welfare indicators, serve as a benchmark for future elephant welfare studies, and aid in decision making with regard to best practices in elephant management. Title: Applying GPS and Accelerometers to the Study of African Savanna (Loxodonta africana) and Asian Elephant (Elephas maximus) Welfare in Zoos Author: Holdgate, Matthew Robert Year: 2015 African savanna elephants (Loxodonta africana) and Asian elephants (Elephas maximus) are a focus of welfare research in zoos due to their high intelligence, complex social structure, and sheer size. Due to these challenges, some argue that zoos are inherently incapable of providing appropriate care for elephants, while others believe that zoos can fulfill the needs of these species with improved husbandry. There is a general consensus from both within and outside of zoos, however, that zoos must improve their elephant programs or cease exhibiting these animals altogether. Now more than ever, applied research on zoo elephant welfare is needed to provide context for this debate. Researchers are interested in how far zoo elephants walk due to the potential health and welfare benefits of walking in these highly mobile species. Zoo researchers recently adopted GPS technology to study elephant walking, and preliminary evidence suggests that African elephants in large zoo exhibits walk distances that correspond with wild elephants under non-extreme conditions. However, data are limited from Asian elephants and from elephants in more typically-sized exhibits. In Chapter Two, I discuss important methodological considerations of utilizing GPS in a zoo environment, including an introduction to the technology, sources of error and mitigation, methods to improve GPS performance, and possible effects of GPS device attachment on animal behavior. This review shows GPS performance is adequate for tracking zoo elephant walking when proper methodological techniques are applied, and should serve as a useful reference for zoo researchers considering using GPS. In Chapter Three, I used GPS anklets to measure outdoor daily walking distance in 56 adult female African (n = 33) and Asian (n = 23) elephants housed in 30 zoos. I collected 259 days of data and found that elephants walked an average of 5.34 km/day with no significant difference between species. Multivariate regression models predicted that elephants with more dynamic feeding regimens (more diverse feeding types and frequencies; unscheduled feeding times) will walk more. Distance walked was also predicted to be higher in elephants that spend time in a greater number of different social groups. Distance walked was predicted to decline with age. Finally, I found a significant negative correlation between distance walked and nighttime space experience. The results of the analysis suggest that zoos that want to increase walking in their elephants need not rely solely on larger exhibits, but can increase walking by adding quality and complexity to exhibits. However, my results failed to establish a definitive link between walking distance and other validated measures of elephant welfare. Thus, the direct health and welfare benefits of walking in zoo elephants remain unresolved. Resting behaviors are an essential component of animal welfare, but have received little attention in zoological research. In Chapter Four, I used accelerometers in anklets to complete the first large-scale multi-species investigation of zoo elephant recumbence. I collected 344 days of data from 72 adult female African (n = 44) and Asian (n = 28) elephants at 40 zoos. I found that African elephants are recumbent an average of 2.14 hours/day, which is significantly less than Asian elephants at 3.22 hours/day. Multivariate regression models predicted that African elephant recumbence increases when they experience more space at night, and Asian elephant recumbence increases when they spend time housed alone. Both species showed a similar response to substrate, such that African elephants spending time on all-hard substrates are predicted to be recumbent less, while Asian elephants spending time on all-soft substrates are predicted to be recumbent more. The discovery that occasional non-recumbence is a common behavior in zoo elephants also introduces a new area of research that may have important animal welfare consequences. Finally, this study established that zoos should continue their efforts to replace hard substrate with soft substrate in order to provide zoo elephants with environments that facilitate recumbence. Overall, this work assessed walking and recumbence in zoo elephants, which will allow zoos to gauge the prevalence of these behaviors in their elephants as compared to the sub-population studied here. A variety of factors that are associated with these behaviors were also identified. With this information, zoos can prioritize modifications to their facilities and animal management programs to create an environment that encourages zoo elephants to express walking and recumbence behavior, should they choose to do so. This work is one component of the Elephant Welfare Project, the largest zoo animal welfare project ever undertaken, and is unprecedented in both scope and scale. The project was funded by the Institute of Museum and Library Services (IMLS), an independent, U.S., federal, grant-making agency that supports libraries, museums, and zoos. At the time of this writing, the first manuscripts from this project are being submitted to academic journals. These papers will describe the prevalence and distribution of a variety of elephant behaviors and welfare indicators, serve as a benchmark for future elephant welfare studies, and aid in decision making with regard to best practices in elephant management. Close

• 254. [Article] Population Structure of Island-Associated Pantropical Spotted Dolphins (Stenella attenuata) in Hawaiian Waters

  Understanding gene flow, diversity, and dispersal patterns is important for predicting effects of natural events and anthropogenic activities on dolphin populations. With the very recent exceptions of ...

  Citation × Citation Citation Abstract Copy Title: Population Structure of Island-Associated Pantropical Spotted Dolphins (Stenella attenuata) in Hawaiian Waters Author: Courbis, Sarah Shelby Year: 2011 Understanding gene flow, diversity, and dispersal patterns is important for predicting effects of natural events and anthropogenic activities on dolphin populations. With the very recent exceptions of false killer whales (Pseudorca crassidens), spinner dolphins (Stenella longirostris), and common bottlenose dolphins (Tursiops truncatus), Hawaiian odontocete species are managed as single stocks within the U.S. Hawaiian Exclusive Economic Zone. These exceptions are a result of recent studies that have indicated that some species have populations that show fidelity to individual islands or groups of islands, resulting in genetic differentiation, often with management implications. The first part of my study (following the introductory chapter) focused on population structure of pantropical spotted dolphins (Stenella attenuata) near the Hawaiian Islands. Because of the level of human interaction, pantropical spotted dolphin populations need to be defined accurately to be managed in a way that will avoid local population losses, especially given that the commercial and recreational troll fisheries near the islands "fish on dolphins" to catch tuna. I analyzed genetic samples for mtDNA and microsatellite loci from four island regions: Hawai'i, the 4-islands area, O'ahu, and Kaua'i/Ni'ihau. My results support genetic differentiation among the regions of Hawai'i, the 4-islands area, and O'ahu and suggest that pantropical spotted dolphins near Kaua'i/Ni'ihau are likely transient and in very low numbers. There was no strong evidence to support sex-biased dispersal or group fidelity. Possibly, differentiation is mediated by behavior adapted to differing habitat types. From a management perspective, spinner and bottlenose dolphin populations near the Hawaiian Islands have been split into separate stocks for management based on levels of genetic differentiation similar to those found for pantropical spotted dolphins. These precedents suggest that comparable action should be taken to split pantropical spotted dolphin stocks near the Hawaiian Islands. Most population studies rely heavily upon fixation indicies like FST to determine whether populations are genetically differentiated. When FST values are low but significantly different from zero, it can be difficult to interpret the biological significance of these values. As part of my study, I suggest that one way to evaluate whether small FST values indicate significant differentiation is to compare FST values with other populations considered to be separate based on factors such as extreme distance or morphological differences. I examined pantropical spotted dolphins from the coastal and offshore Eastern Tropical Pacificm (ETP), Hawaiian Islands, and China/Taiwan to examine the utility of comparing FST values across separate populations. Among Hawaiian Island regions, FST values are significantly different from zero but small. The comparison of these FST values with more distant populations in the ETP and China/Taiwan indicated that differences among Hawaiian Island regions were similar in magnitude to those found between the offshore and coastal ETP sub-species, but smaller than between the Hawaiian Island regions and the other regions examined. This suggests a level of reproductive isolation among the Hawaiian Islands regions that is comparable to that of offshore and coastal ETP populations, and supports the value of fixation index comparisons in evaluating differentiation among putative populations. My results suggest that assigning specific numerical baseline FST values may not always be biologically meaningful but that determining whether related populations with geographic or other separation show a preponderance of similar, lower, or higher fixation index values can help evaluate whether genetic differences among sympatric or parapatric groups warrants designating them as separate populations for management. Lastly, I explore whether the fast evolving mtDNA control region may be more suited to phylogenetic comparisons among the Stenella than slower evolving gene regions and whether the small number of haplotypes generally used in phylogenetic analyses is adequate for defining relationships among dolphins. Usually, slow evolving regions, such as gene regions, are used in phylogenetic analyses because species and genera have been isolated long enough for variation to have accumulated in such regions but not so long that many reversals (i.e. a mutational change in sequence that later changes back to the original sequence) have occured. The mtDNA control region is typically used for population genetic comparisons rather than phylogenetic comparisons because it is considered to be a fast evolving region. Historically, dolphin phylogeny has been examined using gene regions, which have resulted in ambiguous and unexpected relationships. However, the lack of variation in the mtDNA control region for pantropical spotted dolphin populations and the fact that recent studies have found that the mtDNA control region in cetaceans evolves at about one quarter the rate of other mammals, raises the question as to whether this region would be better suited to phylogenetic studies for the Stenella (and potentially other dolphin species). In comparing 346 haplotypes from five species of Stenella world-wide, I found that the mtDNA control region is probably not a good region to use for phylogenetic analyses, and that even faster evolving regions might perform better. The differences in the mtDNA control region were not sufficient to distinguish clear relationships among the Stenella. I also found that when subsets of haplotypes chosen at random were compared, the results differed among comparisons, suggesting that there is value in using more than the usual one or two haplotypes when making phylogentic comparisons. Given the recent increases in sequence availability (e.g. GenBank) and computing power, researchers should strongly consider using many haplotypes from a variety of populations in their phylogenetic comparisons. Title: Population Structure of Island-Associated Pantropical Spotted Dolphins (Stenella attenuata) in Hawaiian Waters Author: Courbis, Sarah Shelby Year: 2011 Understanding gene flow, diversity, and dispersal patterns is important for predicting effects of natural events and anthropogenic activities on dolphin populations. With the very recent exceptions of false killer whales (Pseudorca crassidens), spinner dolphins (Stenella longirostris), and common bottlenose dolphins (Tursiops truncatus), Hawaiian odontocete species are managed as single stocks within the U.S. Hawaiian Exclusive Economic Zone. These exceptions are a result of recent studies that have indicated that some species have populations that show fidelity to individual islands or groups of islands, resulting in genetic differentiation, often with management implications. The first part of my study (following the introductory chapter) focused on population structure of pantropical spotted dolphins (Stenella attenuata) near the Hawaiian Islands. Because of the level of human interaction, pantropical spotted dolphin populations need to be defined accurately to be managed in a way that will avoid local population losses, especially given that the commercial and recreational troll fisheries near the islands "fish on dolphins" to catch tuna. I analyzed genetic samples for mtDNA and microsatellite loci from four island regions: Hawai'i, the 4-islands area, O'ahu, and Kaua'i/Ni'ihau. My results support genetic differentiation among the regions of Hawai'i, the 4-islands area, and O'ahu and suggest that pantropical spotted dolphins near Kaua'i/Ni'ihau are likely transient and in very low numbers. There was no strong evidence to support sex-biased dispersal or group fidelity. Possibly, differentiation is mediated by behavior adapted to differing habitat types. From a management perspective, spinner and bottlenose dolphin populations near the Hawaiian Islands have been split into separate stocks for management based on levels of genetic differentiation similar to those found for pantropical spotted dolphins. These precedents suggest that comparable action should be taken to split pantropical spotted dolphin stocks near the Hawaiian Islands. Most population studies rely heavily upon fixation indicies like FST to determine whether populations are genetically differentiated. When FST values are low but significantly different from zero, it can be difficult to interpret the biological significance of these values. As part of my study, I suggest that one way to evaluate whether small FST values indicate significant differentiation is to compare FST values with other populations considered to be separate based on factors such as extreme distance or morphological differences. I examined pantropical spotted dolphins from the coastal and offshore Eastern Tropical Pacificm (ETP), Hawaiian Islands, and China/Taiwan to examine the utility of comparing FST values across separate populations. Among Hawaiian Island regions, FST values are significantly different from zero but small. The comparison of these FST values with more distant populations in the ETP and China/Taiwan indicated that differences among Hawaiian Island regions were similar in magnitude to those found between the offshore and coastal ETP sub-species, but smaller than between the Hawaiian Island regions and the other regions examined. This suggests a level of reproductive isolation among the Hawaiian Islands regions that is comparable to that of offshore and coastal ETP populations, and supports the value of fixation index comparisons in evaluating differentiation among putative populations. My results suggest that assigning specific numerical baseline FST values may not always be biologically meaningful but that determining whether related populations with geographic or other separation show a preponderance of similar, lower, or higher fixation index values can help evaluate whether genetic differences among sympatric or parapatric groups warrants designating them as separate populations for management. Lastly, I explore whether the fast evolving mtDNA control region may be more suited to phylogenetic comparisons among the Stenella than slower evolving gene regions and whether the small number of haplotypes generally used in phylogenetic analyses is adequate for defining relationships among dolphins. Usually, slow evolving regions, such as gene regions, are used in phylogenetic analyses because species and genera have been isolated long enough for variation to have accumulated in such regions but not so long that many reversals (i.e. a mutational change in sequence that later changes back to the original sequence) have occured. The mtDNA control region is typically used for population genetic comparisons rather than phylogenetic comparisons because it is considered to be a fast evolving region. Historically, dolphin phylogeny has been examined using gene regions, which have resulted in ambiguous and unexpected relationships. However, the lack of variation in the mtDNA control region for pantropical spotted dolphin populations and the fact that recent studies have found that the mtDNA control region in cetaceans evolves at about one quarter the rate of other mammals, raises the question as to whether this region would be better suited to phylogenetic studies for the Stenella (and potentially other dolphin species). In comparing 346 haplotypes from five species of Stenella world-wide, I found that the mtDNA control region is probably not a good region to use for phylogenetic analyses, and that even faster evolving regions might perform better. The differences in the mtDNA control region were not sufficient to distinguish clear relationships among the Stenella. I also found that when subsets of haplotypes chosen at random were compared, the results differed among comparisons, suggesting that there is value in using more than the usual one or two haplotypes when making phylogentic comparisons. Given the recent increases in sequence availability (e.g. GenBank) and computing power, researchers should strongly consider using many haplotypes from a variety of populations in their phylogenetic comparisons. Close

• 255. [Article] Spatial Segregation of the Sexes in a Salt Marsh Grass Distichlis spicata (Poaceae)

  Understanding the maintenance of sexual systems is of great interest to evolutionary and ecological biologists because plant systems are extremely varied. Plant sexual systems have evolved to include not ...

  Citation × Citation Citation Abstract Copy Title: Spatial Segregation of the Sexes in a Salt Marsh Grass Distichlis spicata (Poaceae) Author: Mercer, Charlene Ashley Year: 2010 Understanding the maintenance of sexual systems is of great interest to evolutionary and ecological biologists because plant systems are extremely varied. Plant sexual systems have evolved to include not only complete plants with both male and female reproduction occurring on one plant (i.e., monoecious and hermaphroditic) but also plants with male and female function on separate plants (dioecious). The dioecious reproductive system can be used to test theories on niche differentiation given that having separate plants potentially allows for the exploitation of a broader niche. This increase in the realized niche is due to the ability for separate sexes to occupy different niches, which may occur in different physical habitats. Some dioecious plants have been shown to occur in areas biased to nearly 100% male or nearly 100% female, called spatial segregation of the sexes (SSS). Occupying a broader niche could increase fitness in some species when the separation is used for one sex to gain access to resources that increase reproductive success and/or if the separation inhibits deleterious competition. These two mechanisms have been previously proposed for the evolution of SSS in dioecious plants. The first mechanism suggests that males and females have evolved to occupy different niches due to differences in reproduction (sexual specialization). The hypothesis for the sexual specialization mechanism is that females should have higher fitness in female-majority sites and males should have higher fitness in male-majority sites. The second mechanism states that males and females occupy different niches due to competition between the sexes (niche partitioning). The hypothesis for niche partitioning states that inter-sexual competition should decrease fitness more than intra-sexual competition. These mechanisms are not mutually exclusive. In our research we use the salt-marsh grass Distichlis spicata as our study species because this plant is dioecious and because molecular markers have been developed to determine the sex of juvenile plants. These molecular markers are important for testing the niche partitioning hypothesis for SSS in juveniles. Furthermore, previous work in California has shown that plants occur in areas nearly 100% female and nearly 100% male called spatial segregation of the sexes (SSS). The previous research also showed that female-majority sites were higher in soil phosphorus than male-majority sites. We conduct all research, presented in the proceeding chapters, on Distichlis spicata in the Sand Lake estuary near Pacific City, Oregon and in the laboratory at Portland State University. In Chapter 1 we used field data to answer two questions: (1) Does Distichlis spicata exhibit SSS in Oregon, and (2) If SSS is occurring, do differences occur in plant form and function (sexual specialization) in reproductive female and male plants in female-majority and male-majority sites? We used a sex ratio survey and collected field data on reproductive males and females. Our results show that there are female-majority and male-majority areas and SSS is occurring in the Sand Lake Estuary. Results from our native plant data suggest that reproductive females perform better in female-majority sites compared to male-majority sites which could suggest that sexual specialization is occurring in females. We currently have a long term field reciprocal transplant experiment in place to further address this hypothesis. In Chapter 2 we use field dada to address the following questions: (1) Does site-specific soil nutrient content occur in August, when females have set seed? (2) Does sex-specific mycorrhizal colonization occur in reproductively mature plants? (3) Does sex-specific mycorrhizal colonization vary seasonally in natural populations? Inside the roots of D. spicata a symbiotic relationship is formed between plant and arbuscular mycorrhizal fungus (AM). The AM- plant relationship has been shown to thrive in phosphorus limited areas because the mycorrhizal fungus increases nutrient access to the plant. We analyzed the results of the field soil nutrient content and mycorrhizal colonization in roots of native Distichlis spicata from male-majority and female-majority sites. The root colonization included staining roots with trypan blue and viewing sections of the roots under the microscope. Our results show that female- majority sites are higher in phosphorus and are found to have higher AM colonization than male- majority sites in the field. In Chapter 3 we then reciprocally transplanted D. spicata plants in the field to address the following questions: (1) Does niche partitioning occur in D. spicata, and (2) If niche partitioning is occurring, which plants are competing more? Our reciprocal transplant experiment included seeds grown in intra-sexual, inter-sexual and no competition in cones, planted directly into the field, and allowed to grow for 15 months. After the 15 months was over we measured survival, dry weight and root/shoot ratio. The design of the experiment was to determine the effects of competition (intra-sexual and inter-sexual) and no competition on (single male and female) on survival, biomass and root/shoot ratios. Our results show that niche partitioning is occurring and plants in inter-sexual competition have significantly less biomass then intra-sexual competitors. In, Chapter 4, we conduct a laboratory experiment to address the following questions: (1) Do plants show plasticity in their response to root exudates of the competing plant in regards to the sexual phenotype of the competitor? (2) Do plants show plasticity in their response to root exudates of the competing plant with respect to the relatedness of the competitor? We use sterile seeds grown in 24-well plates containing liquid media. For each competing plant, we picked plants up out of the wells and into the competing plants wells so that plants only experienced media that the competing plant had grown. At no time do roots ever come into contact with one another. We measured primary root length, number of lateral roots, the number of root hairs, root/shoot ratio and total dry weight. We analyzed the study two different ways, one for sexual type competition (inter-sexual, intra-sexual, none) and for plant relationship (KIN, STRANGER and OWN). The results for the sexual type competition found that inter-sexual competition was greater for root/shoot ratio and dry weight. The results for plant relationship competition found that kin plants had a significantly greater number of lateral roots and a significantly longer primary root. The last chapter, Chapter 5, includes a summary of our conclusions. Our study found SSS occurring in the Sand Lake Estuary in Oregon with female-majority sites higher in phosphorus and root colonization higher in percent colonization of arbuscular mycorrhizal fungi compared to male-majority sites. Based on the sexual specialization hypothesis as a mechanism for SSS, we found that females had greater fitness in female-majority sites compared to male-majority sites, suggesting that sexual specialization is occurring in reproductive females. We then tested the niche partitioning hypothesis for SSS, and we found consistent lab and field results suggesting that niche partitioning due to inter-sexual competition is an explanation for why females and males D. spicata plants spatially segregate themselves at the juvenile life history stage. Furthermore, we found that plants that have the same mother had a significantly greater number of lateral roots and a significantly longer primary root. These results suggest that KIN plants respond differently to one another compared to plants paired with a plant not from the same mother (STRANGER) or when the plant is alone (OWN). Title: Spatial Segregation of the Sexes in a Salt Marsh Grass Distichlis spicata (Poaceae) Author: Mercer, Charlene Ashley Year: 2010 Understanding the maintenance of sexual systems is of great interest to evolutionary and ecological biologists because plant systems are extremely varied. Plant sexual systems have evolved to include not only complete plants with both male and female reproduction occurring on one plant (i.e., monoecious and hermaphroditic) but also plants with male and female function on separate plants (dioecious). The dioecious reproductive system can be used to test theories on niche differentiation given that having separate plants potentially allows for the exploitation of a broader niche. This increase in the realized niche is due to the ability for separate sexes to occupy different niches, which may occur in different physical habitats. Some dioecious plants have been shown to occur in areas biased to nearly 100% male or nearly 100% female, called spatial segregation of the sexes (SSS). Occupying a broader niche could increase fitness in some species when the separation is used for one sex to gain access to resources that increase reproductive success and/or if the separation inhibits deleterious competition. These two mechanisms have been previously proposed for the evolution of SSS in dioecious plants. The first mechanism suggests that males and females have evolved to occupy different niches due to differences in reproduction (sexual specialization). The hypothesis for the sexual specialization mechanism is that females should have higher fitness in female-majority sites and males should have higher fitness in male-majority sites. The second mechanism states that males and females occupy different niches due to competition between the sexes (niche partitioning). The hypothesis for niche partitioning states that inter-sexual competition should decrease fitness more than intra-sexual competition. These mechanisms are not mutually exclusive. In our research we use the salt-marsh grass Distichlis spicata as our study species because this plant is dioecious and because molecular markers have been developed to determine the sex of juvenile plants. These molecular markers are important for testing the niche partitioning hypothesis for SSS in juveniles. Furthermore, previous work in California has shown that plants occur in areas nearly 100% female and nearly 100% male called spatial segregation of the sexes (SSS). The previous research also showed that female-majority sites were higher in soil phosphorus than male-majority sites. We conduct all research, presented in the proceeding chapters, on Distichlis spicata in the Sand Lake estuary near Pacific City, Oregon and in the laboratory at Portland State University. In Chapter 1 we used field data to answer two questions: (1) Does Distichlis spicata exhibit SSS in Oregon, and (2) If SSS is occurring, do differences occur in plant form and function (sexual specialization) in reproductive female and male plants in female-majority and male-majority sites? We used a sex ratio survey and collected field data on reproductive males and females. Our results show that there are female-majority and male-majority areas and SSS is occurring in the Sand Lake Estuary. Results from our native plant data suggest that reproductive females perform better in female-majority sites compared to male-majority sites which could suggest that sexual specialization is occurring in females. We currently have a long term field reciprocal transplant experiment in place to further address this hypothesis. In Chapter 2 we use field dada to address the following questions: (1) Does site-specific soil nutrient content occur in August, when females have set seed? (2) Does sex-specific mycorrhizal colonization occur in reproductively mature plants? (3) Does sex-specific mycorrhizal colonization vary seasonally in natural populations? Inside the roots of D. spicata a symbiotic relationship is formed between plant and arbuscular mycorrhizal fungus (AM). The AM- plant relationship has been shown to thrive in phosphorus limited areas because the mycorrhizal fungus increases nutrient access to the plant. We analyzed the results of the field soil nutrient content and mycorrhizal colonization in roots of native Distichlis spicata from male-majority and female-majority sites. The root colonization included staining roots with trypan blue and viewing sections of the roots under the microscope. Our results show that female- majority sites are higher in phosphorus and are found to have higher AM colonization than male- majority sites in the field. In Chapter 3 we then reciprocally transplanted D. spicata plants in the field to address the following questions: (1) Does niche partitioning occur in D. spicata, and (2) If niche partitioning is occurring, which plants are competing more? Our reciprocal transplant experiment included seeds grown in intra-sexual, inter-sexual and no competition in cones, planted directly into the field, and allowed to grow for 15 months. After the 15 months was over we measured survival, dry weight and root/shoot ratio. The design of the experiment was to determine the effects of competition (intra-sexual and inter-sexual) and no competition on (single male and female) on survival, biomass and root/shoot ratios. Our results show that niche partitioning is occurring and plants in inter-sexual competition have significantly less biomass then intra-sexual competitors. In, Chapter 4, we conduct a laboratory experiment to address the following questions: (1) Do plants show plasticity in their response to root exudates of the competing plant in regards to the sexual phenotype of the competitor? (2) Do plants show plasticity in their response to root exudates of the competing plant with respect to the relatedness of the competitor? We use sterile seeds grown in 24-well plates containing liquid media. For each competing plant, we picked plants up out of the wells and into the competing plants wells so that plants only experienced media that the competing plant had grown. At no time do roots ever come into contact with one another. We measured primary root length, number of lateral roots, the number of root hairs, root/shoot ratio and total dry weight. We analyzed the study two different ways, one for sexual type competition (inter-sexual, intra-sexual, none) and for plant relationship (KIN, STRANGER and OWN). The results for the sexual type competition found that inter-sexual competition was greater for root/shoot ratio and dry weight. The results for plant relationship competition found that kin plants had a significantly greater number of lateral roots and a significantly longer primary root. The last chapter, Chapter 5, includes a summary of our conclusions. Our study found SSS occurring in the Sand Lake Estuary in Oregon with female-majority sites higher in phosphorus and root colonization higher in percent colonization of arbuscular mycorrhizal fungi compared to male-majority sites. Based on the sexual specialization hypothesis as a mechanism for SSS, we found that females had greater fitness in female-majority sites compared to male-majority sites, suggesting that sexual specialization is occurring in reproductive females. We then tested the niche partitioning hypothesis for SSS, and we found consistent lab and field results suggesting that niche partitioning due to inter-sexual competition is an explanation for why females and males D. spicata plants spatially segregate themselves at the juvenile life history stage. Furthermore, we found that plants that have the same mother had a significantly greater number of lateral roots and a significantly longer primary root. These results suggest that KIN plants respond differently to one another compared to plants paired with a plant not from the same mother (STRANGER) or when the plant is alone (OWN). Close