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• 21. [Article] Small Noncoding RNA Expression During Extreme Anoxia Tolerance of Annual Killifish (Austrofundulus limnaeus) Embryos

  Small noncoding RNAs (sncRNA) have recently emerged as specific and rapid regulators of gene expression, involved in a myriad of cellular and organismal processes. MicroRNAs, a class of sncRNAs, are differentially ...

  Citation × Citation Citation Abstract Copy Title: Small Noncoding RNA Expression During Extreme Anoxia Tolerance of Annual Killifish (Austrofundulus limnaeus) Embryos Author: Riggs, Claire L., Podrabsky, Jason E. Year: 2017 Small noncoding RNAs (sncRNA) have recently emerged as specific and rapid regulators of gene expression, involved in a myriad of cellular and organismal processes. MicroRNAs, a class of sncRNAs, are differentially expressed in diverse taxa in response to environmental stress, including anoxia. In most vertebrates, a brief period of oxygen deprivation results in severe tissue damage or death. Studies on sncRNA and anoxia have focused on these anoxia-sensitive species. Studying sncRNAs in anoxia-tolerant organisms may provide insight into adaptive mechanisms supporting anoxia tolerance. Embryos of the annual killifish Austrofundulus limnaeus are the most anoxia-tolerant vertebrates known, surviving over 100 days at their peak tolerance at 25°C. Their anoxia tolerance and physiology vary over development, such that both anoxia-tolerant and anoxia-sensitive phenotypes comprise the species. This allows for a robust comparison to identify sncRNAs essential to anoxia-tolerance. For this study, RNA sequencing was used to identify and quantify expression of sncRNAs in four embryonic stages of A. limnaeus in response to an exposure to anoxia and subsequent aerobic recovery. Unique stage-specific patterns of expression were identified that correlate with anoxia tolerance. In addition, embryos of A. limnaeus appear to constitutively express stress-responsive miRNAs. Most differentially expressed sncRNAs were expressed at higher levels during recovery. Many novel groups of sncRNAs with expression profiles suggesting a key role in anoxia tolerance were identified, including sncRNAs derived from mitochondrial tRNAs. This global analysis has revealed groups of candidate sncRNAs that we hypothesize support anoxia tolerance. Title: Small Noncoding RNA Expression During Extreme Anoxia Tolerance of Annual Killifish (Austrofundulus limnaeus) Embryos Author: Riggs, Claire L., Podrabsky, Jason E. Year: 2017 Small noncoding RNAs (sncRNA) have recently emerged as specific and rapid regulators of gene expression, involved in a myriad of cellular and organismal processes. MicroRNAs, a class of sncRNAs, are differentially expressed in diverse taxa in response to environmental stress, including anoxia. In most vertebrates, a brief period of oxygen deprivation results in severe tissue damage or death. Studies on sncRNA and anoxia have focused on these anoxia-sensitive species. Studying sncRNAs in anoxia-tolerant organisms may provide insight into adaptive mechanisms supporting anoxia tolerance. Embryos of the annual killifish Austrofundulus limnaeus are the most anoxia-tolerant vertebrates known, surviving over 100 days at their peak tolerance at 25°C. Their anoxia tolerance and physiology vary over development, such that both anoxia-tolerant and anoxia-sensitive phenotypes comprise the species. This allows for a robust comparison to identify sncRNAs essential to anoxia-tolerance. For this study, RNA sequencing was used to identify and quantify expression of sncRNAs in four embryonic stages of A. limnaeus in response to an exposure to anoxia and subsequent aerobic recovery. Unique stage-specific patterns of expression were identified that correlate with anoxia tolerance. In addition, embryos of A. limnaeus appear to constitutively express stress-responsive miRNAs. Most differentially expressed sncRNAs were expressed at higher levels during recovery. Many novel groups of sncRNAs with expression profiles suggesting a key role in anoxia tolerance were identified, including sncRNAs derived from mitochondrial tRNAs. This global analysis has revealed groups of candidate sncRNAs that we hypothesize support anoxia tolerance. Close

• 22. [Article] Characterization of Functional Domains of Cul3, an E3 Ubiquitin Ligase, Using Chimeric Analysis

  Modification of cellular proteins with molecules of ubiquitin is an important process that regulates the activity of cellular proteins. Cullin RING ligases (CRLs) are multi-subunit complexes that act in ...

  Citation × Citation Citation Abstract Copy Title: Characterization of Functional Domains of Cul3, an E3 Ubiquitin Ligase, Using Chimeric Analysis Author: Mitchell, Jennifer Anne Year: 2014 Modification of cellular proteins with molecules of ubiquitin is an important process that regulates the activity of cellular proteins. Cullin RING ligases (CRLs) are multi-subunit complexes that act in concert with E2 enzymes to attach molecules of ubiquitin to protein substrates. There are seven CRLs in mammalian cells (Cul1, Cul2, Cul3, Cul4A, Cul4B, Cul5, and Cul7) that are highly homologous in sequence and structure. CRLs possess a highly conserved C- terminal domain that interacts with E2 enzymes, and a more variable N- terminal domain which recruits substrates through distinct substrate adapter molecules. Despite the structural similarity, these CRLs recognize distinct substrates and carry out unique functions in cells. In order to characterize the functional domains of cullins that are responsible for their unique activity, we generated cullin chimeras for expression and analysis in mammalian cells. These chimeras are Cul3 mutants in which the C- terminal domain or N- terminal domain of Cul3 has been replaced by that of Cul1 or Cul2, respectively. These chimeras were cloned into a mammalian expression vector for the purpose of experimentation in cultured cells. The chimeric cullin constructs provided a valuable tool for investigating how different functional domains of CRLs contribute to their specific functions in cells. In this study, we first investigated if the chimeras that we engineered were able to interact with their respective substrate adapters. We performed co- immunoprecipitation experiments in which we tested the ability of wild type, chimeric, or mutant cullin proteins to bind to three different substrate adapter proteins. We found that the chimera possessing the C- terminus of Cul1 and the N- terminus of Cul3 retains the ability to interact with the BTB substrate adapters Ctb57 and KLHL3. We also found that the chimera that possesses the C- terminus of Cul3 and the N- terminus of Cul1 was unable to interact with BTB proteins. Lastly, we found that the Cul1 adapter Skp1 was able to bind to Cul1, but did not bind to Cul3 or either chimera. We concluded that the chimera possessing the N- terminus of Cul3 likely retains the functional binding abilities of Cul3 at the N- terminus and would therefore be useful for conducting experiments. In this study, we also used the cullin chimeras to investigate the binding interactions between E2 enzymes and cullin RING ligases. We performed co- immunoprecipitation assays to examine the interactions between E2 enzymes and wild type, mutant or chimeric cullin proteins. We found that E2 enzyme UbE2E1 selectively binds to Cul3 and not to Cull. Notably, the BTB binding region at the N- terminus of Cul3 is required for binding to UbE2E1. Furthermore, we found that UbE2E1 also binds to Cul3 substrate adapter protein Ctb57. These experiments revealed a novel interaction between and E2 enzyme and the N- terminus of Cul3, as well as with a Cul3 substrate adapter protein. In conclusion, the chimeras generated in this study have provided valuable information regarding what regions of CRLs are important for interactions with other proteins, and will continue to be a useful tool for investigating CRL structure and function. Title: Characterization of Functional Domains of Cul3, an E3 Ubiquitin Ligase, Using Chimeric Analysis Author: Mitchell, Jennifer Anne Year: 2014 Modification of cellular proteins with molecules of ubiquitin is an important process that regulates the activity of cellular proteins. Cullin RING ligases (CRLs) are multi-subunit complexes that act in concert with E2 enzymes to attach molecules of ubiquitin to protein substrates. There are seven CRLs in mammalian cells (Cul1, Cul2, Cul3, Cul4A, Cul4B, Cul5, and Cul7) that are highly homologous in sequence and structure. CRLs possess a highly conserved C- terminal domain that interacts with E2 enzymes, and a more variable N- terminal domain which recruits substrates through distinct substrate adapter molecules. Despite the structural similarity, these CRLs recognize distinct substrates and carry out unique functions in cells. In order to characterize the functional domains of cullins that are responsible for their unique activity, we generated cullin chimeras for expression and analysis in mammalian cells. These chimeras are Cul3 mutants in which the C- terminal domain or N- terminal domain of Cul3 has been replaced by that of Cul1 or Cul2, respectively. These chimeras were cloned into a mammalian expression vector for the purpose of experimentation in cultured cells. The chimeric cullin constructs provided a valuable tool for investigating how different functional domains of CRLs contribute to their specific functions in cells. In this study, we first investigated if the chimeras that we engineered were able to interact with their respective substrate adapters. We performed co- immunoprecipitation experiments in which we tested the ability of wild type, chimeric, or mutant cullin proteins to bind to three different substrate adapter proteins. We found that the chimera possessing the C- terminus of Cul1 and the N- terminus of Cul3 retains the ability to interact with the BTB substrate adapters Ctb57 and KLHL3. We also found that the chimera that possesses the C- terminus of Cul3 and the N- terminus of Cul1 was unable to interact with BTB proteins. Lastly, we found that the Cul1 adapter Skp1 was able to bind to Cul1, but did not bind to Cul3 or either chimera. We concluded that the chimera possessing the N- terminus of Cul3 likely retains the functional binding abilities of Cul3 at the N- terminus and would therefore be useful for conducting experiments. In this study, we also used the cullin chimeras to investigate the binding interactions between E2 enzymes and cullin RING ligases. We performed co- immunoprecipitation assays to examine the interactions between E2 enzymes and wild type, mutant or chimeric cullin proteins. We found that E2 enzyme UbE2E1 selectively binds to Cul3 and not to Cull. Notably, the BTB binding region at the N- terminus of Cul3 is required for binding to UbE2E1. Furthermore, we found that UbE2E1 also binds to Cul3 substrate adapter protein Ctb57. These experiments revealed a novel interaction between and E2 enzyme and the N- terminus of Cul3, as well as with a Cul3 substrate adapter protein. In conclusion, the chimeras generated in this study have provided valuable information regarding what regions of CRLs are important for interactions with other proteins, and will continue to be a useful tool for investigating CRL structure and function. Close

• 23. [Article] Developmental Mechanisms that Support Genome Stability and Embryonic Survival in Stress-tolerant Embryos of the Annual Killifish <i>Austrofundulus limnaeus</i>

  In order to complete their life cycles, vertebrates require oxygen and water. However, environments are not always forgiving when it comes to constantly providing these basic needs for vertebrate life. ...

  Citation × Citation Citation Abstract Copy Title: Developmental Mechanisms that Support Genome Stability and Embryonic Survival in Stress-tolerant Embryos of the Annual Killifish <i>Austrofundulus limnaeus</i> Author: Wagner, Josiah Tad Year: 2015 In order to complete their life cycles, vertebrates require oxygen and water. However, environments are not always forgiving when it comes to constantly providing these basic needs for vertebrate life. The annual killifish Austrofundulus limnaeus is possibly the most well described extremophile vertebrate and its embryos have been shown to tolerate extremes in oxygen, salinity, and water availability. This phenotype is likely a result of the annual killifish life history, which includes periods of temporary habitat desiccation and oxygen deprivation, and requires the production of stress-tolerant embryos that depress metabolism in a state of suspended animation, known as diapause. Over the past several decades, the basic morphology and physiology of annual killifish development has become better characterized. However, there are still basic cellular processes that remain to be described in annual killifish such as A. limnaeus. Specifically, changes in DNA structure, expression, and copy number are known to have profound impacts on the phenotype and survival of an organism. Little is known as to how A. limnaeus maintains genome integrity during cell stress, nor how the A. limnaeus nuclear and mitochondrial genomes may have evolved under the unpredictable conditions in which A. limnaeus thrive. Early annual killifish embryonic development is also characterized by a complete dispersion and subsequent reaggregation of embryonic blastomeres prior to formation of the embryonic axis. This unusual period of early development may provide a functional adaptation that allows annual killifish embryos to survive these extreme conditions. The overall goals of this project were to (1) characterize the ability of A. limnaeus to tolerate and repair DNA damage through enzymatic and developmental mechanisms, (2) to determine possible consequences of mitochondrial DNA sequence and copy number on the metabolism of A. limnaeus, and (3) to establish a draft genome of A. limnaeus for future comparative genome studies. The results of this project show that embryos of A. limnaeus have an impressive ability to survive and reverse high doses of DNA damage induced by ultraviolet-C (UV-C) radiation, especially when allowed to recover under photoreactivating light. Surprisingly, embryos that survived irradiation during blastomere dispersion phases were able to develop normally. Characterization of gene expression during embryonic development for genes important for axis formation and cellular differentiation suggests that A. limnaeus embryos may delay axis formation until several days after epiboly is complete, thus allowing time for cells that become damaged to be replaced by surrounding pluripotent cells. This outcome would represent first case of a developmental buffering stage in a vertebrate. A. limnaeus embryos are also unique in their mitochondrial response to anoxia. Whereas in other species the amount of mitochondrial DNA (mtDNA) copy number fluctuates following extremes in oxygen availability, A. limnaeus embryonic mtDNA remains stable. Additionally, characterization of the fully sequenced A. limnaeus mitochondrial genome reveals possible evolutionary adaptations that may have facilitated dormancy and anoxia tolerance when compared to other species within the Order Cyprinodontiformes. The final chapter of this project characterizes the draft genome of A. limnaeus and I provide evidence suggesting that epigenetic DNA methylation that may be involved in regulating diapause. Title: Developmental Mechanisms that Support Genome Stability and Embryonic Survival in Stress-tolerant Embryos of the Annual Killifish <i>Austrofundulus limnaeus</i> Author: Wagner, Josiah Tad Year: 2015 In order to complete their life cycles, vertebrates require oxygen and water. However, environments are not always forgiving when it comes to constantly providing these basic needs for vertebrate life. The annual killifish Austrofundulus limnaeus is possibly the most well described extremophile vertebrate and its embryos have been shown to tolerate extremes in oxygen, salinity, and water availability. This phenotype is likely a result of the annual killifish life history, which includes periods of temporary habitat desiccation and oxygen deprivation, and requires the production of stress-tolerant embryos that depress metabolism in a state of suspended animation, known as diapause. Over the past several decades, the basic morphology and physiology of annual killifish development has become better characterized. However, there are still basic cellular processes that remain to be described in annual killifish such as A. limnaeus. Specifically, changes in DNA structure, expression, and copy number are known to have profound impacts on the phenotype and survival of an organism. Little is known as to how A. limnaeus maintains genome integrity during cell stress, nor how the A. limnaeus nuclear and mitochondrial genomes may have evolved under the unpredictable conditions in which A. limnaeus thrive. Early annual killifish embryonic development is also characterized by a complete dispersion and subsequent reaggregation of embryonic blastomeres prior to formation of the embryonic axis. This unusual period of early development may provide a functional adaptation that allows annual killifish embryos to survive these extreme conditions. The overall goals of this project were to (1) characterize the ability of A. limnaeus to tolerate and repair DNA damage through enzymatic and developmental mechanisms, (2) to determine possible consequences of mitochondrial DNA sequence and copy number on the metabolism of A. limnaeus, and (3) to establish a draft genome of A. limnaeus for future comparative genome studies. The results of this project show that embryos of A. limnaeus have an impressive ability to survive and reverse high doses of DNA damage induced by ultraviolet-C (UV-C) radiation, especially when allowed to recover under photoreactivating light. Surprisingly, embryos that survived irradiation during blastomere dispersion phases were able to develop normally. Characterization of gene expression during embryonic development for genes important for axis formation and cellular differentiation suggests that A. limnaeus embryos may delay axis formation until several days after epiboly is complete, thus allowing time for cells that become damaged to be replaced by surrounding pluripotent cells. This outcome would represent first case of a developmental buffering stage in a vertebrate. A. limnaeus embryos are also unique in their mitochondrial response to anoxia. Whereas in other species the amount of mitochondrial DNA (mtDNA) copy number fluctuates following extremes in oxygen availability, A. limnaeus embryonic mtDNA remains stable. Additionally, characterization of the fully sequenced A. limnaeus mitochondrial genome reveals possible evolutionary adaptations that may have facilitated dormancy and anoxia tolerance when compared to other species within the Order Cyprinodontiformes. The final chapter of this project characterizes the draft genome of A. limnaeus and I provide evidence suggesting that epigenetic DNA methylation that may be involved in regulating diapause. Close

• 24. [Article] Predicting Parturition in a Long-Gestating Species: Behavioral and Hormonal Indicators in the Asian Elephant (Elephas maximus)

  Captive populations of Asian elephants (Elephas maximus) in North America are not self-sustaining, and increasing reproductive success within captive populations is a high priority. The ability to accurately ...

  Citation × Citation Citation Abstract Copy Title: Predicting Parturition in a Long-Gestating Species: Behavioral and Hormonal Indicators in the Asian Elephant (Elephas maximus) Author: Velonis, Heather Kelly Year: 2017 Captive populations of Asian elephants (Elephas maximus) in North America are not self-sustaining, and increasing reproductive success within captive populations is a high priority. The ability to accurately predict parturition can have a direct impact on elephant welfare. Elephants in captivity often require significant preparation and management throughout the birthing process, and complications during labor and delivery can necessitate immediate intervention, including stillbirth, protracted labor, maternal aggression towards a newborn calf, and dystocia. Being able to predict when parturition will commence can ensure appropriate staff is available and adequate monitoring is performed. Routine endocrine sampling can be used to predict parturition in Asian elephants, with a drop in progesterone (P4) to baseline levels signaling parturition in 2-5 days. However, we determined this method is not without limitations, and it is not used in all institutions that house elephants. As changes in hormones regulate and alter behaviors, we investigated behavioral indicators as an additional management tool for predicting parturition, a time of drastic hormone changes. We conducted a study of five pregnancies in Asian elephants at the Oregon Zoo, U.S.A, and Taronga Zoo, Australia, between 2008 and 2012. In Chapter 2, I evaluated progesterone (P4) and cortisol levels across three time periods: Baseline; Pre, (the week preceding the drop in P4); and Post, (the period after the P4 drop). Levels of P4 were significantly lower, and levels of cortisol were significantly higher in the days just prior to parturition. I found considerable intra- and inter-individual variation in both endocrine profiles, which can make endocrine assessments difficult to interpret in real time. In Chapter 3, I investigated whether behaviors in the preparturition period could be predictive of impending parturition in the Asian elephant. ANOVA results indicated a significant difference in the amount of time that elephants spent walking backwards across three time periods (F(2) = 3.723, p = 0.033), with the behavior increasing as parturition approached. These results were supported by a non-parametric Kruskal- Wallis. Using a generalized linear mixed model (GLMM), I found that as P4 levels decrease, walking backwards behavior significantly increases. In Chapter 4, I evaluated investigative trunk behaviors, or “trunk checks”, directed towards the temporal gland near the ear, mammary glands, vulva and anus of the pregnant dam. Investigative behaviors included both self-directed behaviors and those sent from herd mates towards the pregnant dam. Self-directed behaviors are most likely associated with physical changes in the pregnant dam, such as using the trunk to pull on swollen teats. Other-directed behaviors may stem from chemo-sensory signaling or other types of communication between herd mates, such as detecting changes in progesterone or cortisol. I ran GLMM and found that four trunk-check behaviors varied significantly with P4 and/or cortisol profiles. These were: self-checks of mammary glands increased with decreasing P4 levels; herd-mate-checks of mammary glands increased with decreasing P4 levels; self-checks of vulva increased with decreasing P4 levels and increasing cortisol levels; herd-mate-checks of anus increased with increasing cortisol levels. In Chapter 5, I evaluated activity budget behaviors in the pregnant elephants. Generalized comparisons were made to published activity budgets of typical captive Asian elephants. I report that activity budgets are within the range of normal activity, though I note a high level of inter-individual variation. In addition, I compared two sampling techniques, including one-zero and instantaneous sampling, that were used for activity budget data collection. I discuss the different results obtained by each sampling technique. These results are a very promising indication that behaviors, including walking backwards and multiple trunk-check behaviors, are changing over time or with parturition-related hormone profiles. We recommend that keepers, veterinary staff, and other observers that are familiar with the regular behavioral repertoire of a pregnant female should pay close attention to these highlighted behaviors. Keeping track of these behaviors, especially in conjunction with P4 and cortisol tracking, can help staff refine existing windows of expected parturition. Title: Predicting Parturition in a Long-Gestating Species: Behavioral and Hormonal Indicators in the Asian Elephant (Elephas maximus) Author: Velonis, Heather Kelly Year: 2017 Captive populations of Asian elephants (Elephas maximus) in North America are not self-sustaining, and increasing reproductive success within captive populations is a high priority. The ability to accurately predict parturition can have a direct impact on elephant welfare. Elephants in captivity often require significant preparation and management throughout the birthing process, and complications during labor and delivery can necessitate immediate intervention, including stillbirth, protracted labor, maternal aggression towards a newborn calf, and dystocia. Being able to predict when parturition will commence can ensure appropriate staff is available and adequate monitoring is performed. Routine endocrine sampling can be used to predict parturition in Asian elephants, with a drop in progesterone (P4) to baseline levels signaling parturition in 2-5 days. However, we determined this method is not without limitations, and it is not used in all institutions that house elephants. As changes in hormones regulate and alter behaviors, we investigated behavioral indicators as an additional management tool for predicting parturition, a time of drastic hormone changes. We conducted a study of five pregnancies in Asian elephants at the Oregon Zoo, U.S.A, and Taronga Zoo, Australia, between 2008 and 2012. In Chapter 2, I evaluated progesterone (P4) and cortisol levels across three time periods: Baseline; Pre, (the week preceding the drop in P4); and Post, (the period after the P4 drop). Levels of P4 were significantly lower, and levels of cortisol were significantly higher in the days just prior to parturition. I found considerable intra- and inter-individual variation in both endocrine profiles, which can make endocrine assessments difficult to interpret in real time. In Chapter 3, I investigated whether behaviors in the preparturition period could be predictive of impending parturition in the Asian elephant. ANOVA results indicated a significant difference in the amount of time that elephants spent walking backwards across three time periods (F(2) = 3.723, p = 0.033), with the behavior increasing as parturition approached. These results were supported by a non-parametric Kruskal- Wallis. Using a generalized linear mixed model (GLMM), I found that as P4 levels decrease, walking backwards behavior significantly increases. In Chapter 4, I evaluated investigative trunk behaviors, or “trunk checks”, directed towards the temporal gland near the ear, mammary glands, vulva and anus of the pregnant dam. Investigative behaviors included both self-directed behaviors and those sent from herd mates towards the pregnant dam. Self-directed behaviors are most likely associated with physical changes in the pregnant dam, such as using the trunk to pull on swollen teats. Other-directed behaviors may stem from chemo-sensory signaling or other types of communication between herd mates, such as detecting changes in progesterone or cortisol. I ran GLMM and found that four trunk-check behaviors varied significantly with P4 and/or cortisol profiles. These were: self-checks of mammary glands increased with decreasing P4 levels; herd-mate-checks of mammary glands increased with decreasing P4 levels; self-checks of vulva increased with decreasing P4 levels and increasing cortisol levels; herd-mate-checks of anus increased with increasing cortisol levels. In Chapter 5, I evaluated activity budget behaviors in the pregnant elephants. Generalized comparisons were made to published activity budgets of typical captive Asian elephants. I report that activity budgets are within the range of normal activity, though I note a high level of inter-individual variation. In addition, I compared two sampling techniques, including one-zero and instantaneous sampling, that were used for activity budget data collection. I discuss the different results obtained by each sampling technique. These results are a very promising indication that behaviors, including walking backwards and multiple trunk-check behaviors, are changing over time or with parturition-related hormone profiles. We recommend that keepers, veterinary staff, and other observers that are familiar with the regular behavioral repertoire of a pregnant female should pay close attention to these highlighted behaviors. Keeping track of these behaviors, especially in conjunction with P4 and cortisol tracking, can help staff refine existing windows of expected parturition. Close

• 25. [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