Download or read book Characterizing Population Genetic Structure and Inferring the Influence of Landscape Features on Gene Flow in a Temperate Snake Species written by Amanda Tonia Joan Xuereb and published by . This book was released on 2012 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Patterns of genetic diversity in natural systems are influenced by landscape heterogeneity over spatial and temporal scales. Certain natural or anthropogenic landscape features may facilitate or impede organism dispersal and subsequent gene flow. Characterizing the geographical distribution of genetic diversity and identifying the factors contributing to population genetic structure is imperative for maintaining functional connectivity between isolated populations across a fragmented landscape. In this study, I combined genetic data and high-resolution land cover information to investigate patterns of population genetic structure in the threatened eastern hog-nosed snake (Heterodon platirhinos) at its northern range limit in Ontario, Canada. First, using putatively neutral microsatellite markers, I found evidence of genetic differentiation between two geographically disjunct regional populations: in the Carolinian region of southwestern Ontario, and along the eastern shoreline of Georgian Bay. Spatial and non-spatial Bayesian clustering algorithms also detected population genetic structure within each regional population. I found evidence of weak structure within Georgian Bay, roughly corresponding to regions north and south of Parry Sound. A genetic cluster at Wasaga Beach, located at the southern terminus of Georgian Bay, was highly differentiated from other populations, despite its geographic proximity to Georgian Bay. Excess homozygosity and reduced allelic diversity in Wasaga Beach compared to other sampled populations imply a population bottleneck event. Secondly, I inferred the role of landscape features on eastern hog-nosed snake dispersal and subsequent gene flow in the Georgian Bay regional population. Using techniques derived from electrical circuit theory, I estimated pairwise resistance distances between individuals by assigning costs to landscape features that are predicted to impede hog-nosed snake movement: open water, wetland, settlement and agriculture, and roads. Landscape features did not influence genetic structure within Wasaga Beach. However, I found weak evidence for an effect of landscape features, particularly open water and roads, on gene flow in eastern Georgian Bay. This study is the first to examine potential factors driving population genetic structure of eastern hog-nosed snakes and provides an empirical foundation for future tests of demographic models and spatially explicit simulations of gene flow.
Download or read book The Influence of Landscape on Genetic Structure of a Threatened Reptile written by Michelle Francis DiLeo and published by . This book was released on 2011 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the impacts of both natural and anthropogenic landscape features on genetic diversity, population structure and connectivity has important implications for conservation of species living in fragmented environments. Here, I combine population genetic data, detailed land cover information, and computer simulations to explore how landscape shapes genetic structure across two regional populations of the threatened eastern massasauga rattlesnake (Sistrurus catenatus catenatus) in Ontario, Canada: one along the eastern shores of Georgian Bay and the other largely confined to the northern half of the Bruce Peninsula. First I used spatial Bayesian assignment to quantify the genetic population structure within each regional population. I found marked subpopulation structure within eastern Georgian Bay with differentiation of island and mainland snakes, a north-south split within the mainland coinciding with the town of Parry Sound, and evidence of further subdivision within the cluster of snakes north of Parry Sound. In contrast I found no population subdivision within the mainland of the Bruce Peninsula, but genetic distinction of mainland and island snakes. Next, I identified the landscape features that shape spatial genetic structure within regional populations. In eastern Georgian Bay I found local variation in the effect of landscape on populations. North of Parry Sound I found no effect of landscape on inter-individual genetic differentiation, but a strong pattern of isolation-by-distance. In contrast I found that both open water and roads restrict gene flow of snakes south of Parry Sound. I found no evidence of isolation-by-distance or that landscape shape genetic structure within the Bruce Peninsula. Finally I used individual-based, spatially explicit simulations to identify the lag-time associated with the detection of contemporary landscape feature effects on genetic structure of massasaugas, and explore the consequences of using spatially correlated land cover elements in landscape genetic analyses. I found that the genetic consequences of roads could be detected within 2-12 generations when population sizes were small or juvenile dispersal was low. However, I also found that roads could be spuriously identified as impediments to gene flow when spatially correlated features such as water are included in genetic models.
Download or read book The Influence of Landscape on Genetic Divergence of the Prairie Ring necked Snake Diadophis Punctatus Arnyi in Missouri written by María Eugenia.. Degano and published by . This book was released on 2019 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Changes in land use can result in habitat fragmentation, which threatens population viability. Reptiles may be more susceptible to the effects of fragmentation because of their limited dispersal and sensitivity to environmental conditions, which will ultimately impact gene flow among remnant populations. In this study, I used the spatial distribution of Diadophis punctatus arnyi to test hypotheses of landscape effects on the genetic structure of 10 sampling sites in northern Missouri. Genetic distance (FST) among populations was based on six microsatellite markers, and I tested the observed genetic differentiation against a suite of alternative resistance surfaces representing biologically plausible hypotheses of how Ring-necked Snakes perceive the landscape. I modeled distances matrices based on putative movement barriers, Euclidean distance, roads and land cover permeability through accumulated cost of least-cost paths, and evaluated their performance using Mantel tests, two causal modelling frameworks, and the mixed-model maximum-likelihood population-effects approach. All methods performed well showing the significant effect of the Missouri River on the genetic isolation of populations on either side, followed by the effects of roads and wetlands. This study sheds light on resistance to movement by snakes based on changes in land use. The presence of roads and frequently flooded habitats were the primary potential landscape features that hinder habitat connectivity among populations."--Abstract.
Download or read book Geographic Variation Speciation and Clines written by John A. Endler and published by Princeton University Press. This book was released on 1977-09-21 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following a review of the diverse and scattered literature on gene flow and population differentiation, the author discusses the relationships among gene flow, dispersal, and migration. He then summarizes the factors which limit the geographic extent of gene flow, and those which allow steep clines to develop in the absence of barriers to gene flow. His analysis draws on examples from the field, experiments, and single- and multiple-locus models.
Download or read book Using Landscape Genetics to Assess Population Connectivity in a Habitat Generalist written by Tyler Duncan Hether and published by . This book was released on 2010 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the nature of genetic variation in natural populations is an underlying theme of population genetics. In recent years population genetics has benefited from the incorporation of landscape and environmental data into pre-existing models of isolation by distance (IBD) to elucidate features influencing spatial genetic variation. Many of these landscape genetics studies have focused on populations separated by discrete barriers (e.g., mountain ridges) or species with specific habitat requirements (i.e., habitat specialists). One difficulty in using a landscape genetics approach for taxa with less stringent habitat requirements (i.e., generalists) is the lack of obvious barriers to gene flow and preference for specific habitats. My study attempts to fill this information gap to understand mechanisms underlying population subdivision in generalists, using the squirrel treefrog (Hyla squirella) and a system for classifying 'terrestrial ecological systems' (i.e. habitat types). I evaluate this dataset with microsatellite markers and a recently introduced method based on ensemble learning (Random Forest) to identify whether spatial distance, habitat types, or both have influenced genetic connectivity among 20 H. squirella populations. Next, I hierarchically subset the populations included in the analysis based on (1) genetic assignment tests and (2) Mantel correlograms to determine the relative role of spatial distance in shaping landscape genetic patterns. Assignment tests show evidence of two genetic clusters that separate populations in Florida's panhandle (Western cluster) from those in peninsular Florida and southern Georgia (Eastern cluster). Mantel correlograms suggest a patch size of approximately 150 km. Landscape genetic analyses at all three spatial scales yielded improved model fit relative to isolation by distance when including habitat types. A hierarchical effect was identified whereby the importance of spatial distance (km) was the strongest predictor of patterns of genetic differentiation above the scale of the genetic patch. Below the genetic patch, spatial distance was still an explanatory variable but was only approximately 30% as relevant as mesic flatwoods or upland oak hammocks. Thus, it appears that habitat types largely influence patterns of population genetic connectivity at local scales but the signal of IBD becomes the dominant driver of regional connectivity. My results highlight some habitats as highly relevant to increased genetic connectivity at all spatial scales (e.g., upland oak hammocks) while others show no association (e.g., silviculture) or scale specific associations (e.g., pastures only at global scales). Given these results it appears that treating habitat as a binary metric (suitable/non-suitable) may be overly simplistic for generalist species in which gene flow probably occurs in a spectrum of habitat suitability. The overall pattern of spatial genetic and landscape genetic structure identified here provides insight into the evolutionary history and patterns of population connectivity for H. squirella and improves our understanding of the role of matrix composition for habitat generalists.
Download or read book Mammalian Dispersal Patterns written by B. Diane Chepko-Sade and published by Rand Corporation. This book was released on 1987 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mammalian Dispersal Patterns examines the ways that social structure affects population genetics and, in turn, rates of evolution, in mammalian groups. It brings together fieldwork in animal behavior and wildlife biology with theoretical work in demography and population genetics. The focus here is dispersal—whether, how, and when individuals leave the areas where they are born. Theoretical work in population genetics indicates that such social factors as skewed sex ratios, restrictive mating patterns, and delayed age of first reproduction will lower the reproductive variability of a population by reducing the number of genotypes passed from one generation to the next. Field studies have shown that many mammalian species do exhibit many such social characteristics. Among horses, elephant seals, and a number of primates, the majority of females are inseminated by only a fraction of the males. In pacts of wolves and mongooses, usually only the highest-ranking male and female breed in a given season. Although socially restricted mating tends to lower genetic variability in isolated populations, it actually tends to increase genetic variability in subdivided populations with low rates of migration between subunits. Among some species there is little dispersal and thus little gene flow between subpopulations; other species travel far afield before mating. The contributors to this volume examine actual data from populations of mammals, the way patterns of dispersal correlate with the genetic structure of individuals and populations, and mathematical models of population structure. This interdisciplinary approach has an important bearing on work in conservation of both wildlife and zoo populations, for it shows that the home range and the population size needed to maintain genetic variability can differ greatly from one species to the next. The volume also offers a fruitful model for future research.
Download or read book Snakes written by Richard A. Seigel and published by McGraw-Hill Companies. This book was released on 1993 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive reference for herpetologists, biologists, and others interested in such aspects of snakes as their population genetics, neurobiology, functional morphology, behavioral ecology, and evolution. Also includes a chapter on strategies for conservation. Acidic paper. Annotation copyright by Book News, Inc., Portland, OR
Download or read book Snakes written by Stephen J. Mullin and published by Cornell University Press. This book was released on 2011-01-15 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: Destruction of habitat due to urban sprawl, pollution, and deforestation has caused population declines or even extinction of many of the world's approximately 2,600 snake species. Furthermore, misconceptions about snakes have made them among the most persecuted of all animals, despite the fact that less than a quarter of all species are venomous and most species are beneficial because they control rodent pests. It has become increasingly urgent, therefore, to develop viable conservation strategies for snakes and to investigate their importance as monitors of ecosystem health and indicators of habitat sustainability. In the first book on snakes written with a focus on conservation, editors Stephen J. Mullin and Richard A. Seigel bring together leading herpetologists to review and synthesize the ecology, conservation, and management of snakes worldwide. These experts report on advances in current research and summarize the primary literature, presenting the most important concepts and techniques in snake ecology and conservation. The common thread of conservation unites the twelve chapters, each of which addresses a major subdiscipline within snake ecology. Applied topics such as methods and modeling and strategies such as captive rearing and translocation are also covered. Each chapter provides an essential framework and indicates specific directions for future research, making this a critical reference for anyone interested in vertebrate conservation generally or for anyone implementing conservation and management policies concerning snake populations. Contributors: Omar Attum, Indiana University Southeast; Steven J. Beaupre, University of Arkansas; Xavier Bonnet, Centre National de la Recherche Scientifique; Frank T. Burbrink, College of Staten Island-The City University of New York; Gordon M. Burghardt, University of Tennessee; Todd A. Castoe, University of Colorado; David Chiszar, University of Colorado; Michael E. Dorcas, Davidson College; Lara E. Douglas, University of Arkansas; Christopher L. Jenkins, Project Orianne, Ltd.; Glenn Johnson, State University of New York at Potsdam; Michael Hutchins, The Wildlife Society; Richard B. King, Northern Illinois University; Bruce A. Kingsbury, Indiana University-Purdue University Fort Wayne; Thomas Madsen, University of Wollongong; Stephen J. Mullin, Eastern Illinois University; James B. Murphy, National Zoological Park; Charles R. Peterson, Idaho State University; Kent A. Prior, Parks Canada; Richard A. Seigel, Towson University; Richard Shine, University of Sydney; Kevin T. Shoemaker, College of Environmental Science and Forestry, State University of New York; Patrick J. Weatherhead, University of Illinois; John D. Willson, University of Georgia
Download or read book Garter Snake Population Connectivity in a New Mexico Watershed of the Southern Rocky Mountains written by Lisa M. McBride and published by . This book was released on 2019 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The genus of garter snakes is comprised of over 30 species that primarily depend on riparian habitat to survive. Riparian zones in the southwestern United States are being threatened even further with climate predictions projecting less rainfall and more severe drought. In this study, I used microsatellite markers to assess the population genetic structure of wandering garter snakes (Thamnophis elegans vagrans) living throughout the Mora River watershed in northeastern New Mexico across five sampling sites. Despite the watershed covering a large area, all 144 garter snakes sampled were found to belong to one regional genetic population. However, there was significant genetic structure between sampling sites. The lowest levels of genetic diversity and gene flow were observed at sites with lower habitat quality associated with increased anthropogenic activities. In comparison, Rio Mora National Wildlife Refuge has a high habitat quality index and hosts garter snakes with greater genetic diversity, private alleles, and connectivity to nearby sites. This locally abundant snake species was useful in detecting barriers to gene flow and corridor space in the watershed indicating high priority areas where restoration efforts may facilitate animal movement.
Download or read book Genetics Demography and Viability of Fragmented Populations written by Andrew G. Young and published by Cambridge University Press. This book was released on 2000-10-12 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed introduction to the genetic and demographic issues relevant to the conservation of fragmented populations.
Download or read book Population Genetic Structure of Rhizomatous Picrorhiza Kurrooa Royle written by Mir Abid Hussain and published by LAP Lambert Academic Publishing. This book was released on 2011-03 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Population genetic structure can be defined as the temporal distribution of gene and genotype frequencies of a population. In support of the isolation by distance model of Wright (1943) simulations shows that under restricted gene flow and selective neutrality, the population as a whole develops a patchy distribution of genotypes. In this study 3 populations of Picrorhiza kurrooa were sampled from habitats that may have different historical geologic processes. The region under study is a physiographically complex mountainous territory, so it represents an excellent model system to study the effect of mountain ranges as barriers to interpopulational gene flow. One population was located in the greater Himalayas (Ladakh range) and lies to the north of the main Himalaya the other 2 populations were collected from middle Himalayans (Sonamarg and Gurez) to the south of the Himalayan terrain. Spatial analysis of population genetic structure by RAPD provides relevant molecular genetic information about fragmentation patterns and landscape genetics that shape population genetic structure and adaptive genetic variation in natural populations of Picrorhiza kurrooa.
Download or read book Population Viability and Connectivity of the Federally Threatened Eastern Indigo Snake in Central Peninsular Florida written by Javan Bauder and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the factors influencing the likelihood of persistence of real-world populations requires both an accurate understanding of the traits and behaviors of individuals within those populations (e.g., movement, habitat selection, survival, fecundity, dispersal) but also an understanding of how those traits and behaviors are influenced by landscape features. The federally threatened eastern indigo snake (EIS, Drymarchon couperi) has declined throughout its range primarily due to anthropogenically-induced habitat loss and fragmentation making spatially-explicit assessments of population viability and connectivity essential for understanding its current status and directing future conservation efforts. The primary goal of my dissertation was to understand how landscape features influence EIS population viability and connectivity in central peninsular Florida. I accomplished this through four components. First, I evaluated EIS movement patterns and space use including daily movement distance, home range size, within-individual home range overlap, and among-individual home range overlap and how these patterns varied by sex and season. Second, I conducted a multi-level, multi-scale habitat selection analysis to create spatially-explicit estimates of EIS habitat selection. Third, using the aforementioned data and previously published data, I developed an agent-based model for simulating EIS movement, survival, reproduction, and dispersal in central Florida. I used this model to determine how landscape features and conservation lands influence EIS occupancy across our study landscape. Finally, I used landscape genetics to determine how landscape features influenced genetic connectivity and to estimate resistance surfaces with which to model potential corridors. I found that male EIS maintain larger home ranges than females and move extensively during the breeding season in search of females. While seasonal home ranges within an individual strongly overlapped, individuals avoided home ranges of same-sex conspecifics. EIS selected home ranges and within-home range locations in areas of undeveloped upland habitat with high habitat heterogeneity and generally avoided urban. While EIS did not avoid roads, they rarely crossed primary and secondary roads. I used observed patterns of movement and habitat selection to calibrate my ABM. My ABM simulated larger male home ranges and smaller home ranges and lower survival in urbanized landscapes although simulated effect sizes were weaker than observed effect sizes. My model was unable to simulate observed patterns of within-individual home range overlap but accurately simulated survival in developed and undeveloped landscapes. EIS occupancy after a 15 year simulation was 56% and occupancy was most strongly affected, negatively, by urbanization. While the presence of conservation lands was not a strong driver of EIS occupancy, EIS occupancy was more consistently higher on conservation lands. EIS gene flow was most strongly associated with undeveloped uplands, urbanization, and habitat edge at the broadest scales we evaluated. Potential corridors were widespread in the southern half of our study area with substantial areas of potential habitat and corridor occurring outside of the existing conservation network. This work indicates that the LWR contains extensive areas capable of supporting EIS although increasing urbanization may have a negative impact on future persistence of EIS.
Download or read book Origins of Genetic Variation and Population Structure of Foxsnakes Across Spatial and Temporal Scales written by Jeffrey Ryan Row and published by . This book was released on 2011 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the events and processes responsible for patterns of within species diversity, provides insight into major evolutionary themes like adaptation, species distributions, and ultimately speciation itself. Here, I combine ecological, genetic and spatial perspectives to evaluate the roles that both historical and contemporary factors have played in shaping the population structure and genetic variation of foxsnakes (Pantherophis gloydi). First, I determine the likely impact of habitat loss on population distribution, through radio-telemetry (32 individuals) at two locations varying in habitat patch size. As predicted, individuals had similar habitat use patterns, but restricted movements to patches of suitable habitat at the more disturbed site. Also, occurrence records spread across a fragmented region were non-randomly distributed and located close to patches of usable habitat, suggesting habitat distribution limits population distribution. Next, I combined habitat suitability modeling with population genetics (589 individuals, 12 microsatellite loci) to infer how foxsnakes disperse through a mosaic of natural and altered landscape features. Boundary regions between genetic clusters were comprised of low suitability habitat (e.g. agricultural fields). Island populations were grouped into a single genetic cluster suggesting open water presents less of a barrier than non-suitable terrestrial habitat. Isolation by distance models had a stronger correlation with genetic data when including resistance values derived from habitat suitability maps, suggesting habitat degradation limits dispersal for foxsnakes. At larger temporal and spatial scales I quantified patterns of genetic diversity and population structure using mitochondrial (101 cytochrome b sequences) and microsatellite (816 individuals, 12 loci) DNA and used Approximate Bayesian computation to test competing models of demographic history. Supporting my predictions, I found models with populations which have undergone population size drops and splitting events continually had more support than models with small founding populations expanding to stable populations. Based on timing, the most likely cause was the cooling of temperatures and infilling of deciduous forest since the Hypisthermal. On a smaller scale, evidence suggested anthropogenic habitat loss has caused further decline and fragmentation. Mitochondrial DNA structure did not correspond to fragmented populations and the majority of foxsnakes had an identical haplotype, suggesting a past bottleneck or selective sweep.
Download or read book Using Microsatellite Loci to Determine the Fine Scale Genetic Structure of a Complex of Timber Rattlesnake Crotalus Horridus Dens in Northeastern New York written by AnnMarie Clark and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Most genetic diversity was found among individuals of the general population. The close genetic relationship between two dens in different den groups supported the hypothesis that microhabitat influences the snakes choice of dens. These findings were statistically supported and indicated some degree of interbreeding within den groups. An area where genetic exchange occurs between two of the den groups has resulted in a significant amount of within-population genetic diversity. The results further suggest that this series of timber rattlesnake dens represents a healthy, stable metapopulation. A major roadway is apparently an ineffective barrier to gene flow between some dens within one of the den groups, and the common area where two populations go to breed allows for moderate gene flow among other den groups. Conservation and management plans need to address the specific needs of this species at specific localities. Genetic analysis of spatial population structure needs to be applied to other areas to design management plans appropriate for the specific site.
Download or read book Spatial Ecology Genetic Diversity and Population Structure of Armenian Vipers Montivipera Raddei in Two Different Landscapes written by Jeffery Alan Ettling and published by . This book was released on 2013 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an effort to gain a better understanding of the impact that human-modified landscapes are having on snake populations I studied the spatial ecology, gene diversity and population structure of the Armenian Viper, Montivipera raddei in two different landscapes in Armenia. We first examined the spatial ecology and habitat use of Armenian Vipers in a human-modified landscape with a combination of agricultural fields and overgrazed native steppe habitat. While there were no differences in movement rates for either sex through croplands compared to steppe, we did find that males had larger home ranges during the spring if it included cropland. While the mosaic of steppe and croplands does not appear to impede seasonal movements in this human-modified landscape, vipers overwhelmingly prefer steppe to cropland. We were then interested in how the spatial use of vipers in this heavily altered habitat compared to a population inhabiting a recovered-natural habitat. The home range size and mean movements were significantly smaller and the abundance of small mammals was significantly higher in the recovered-natural landscape. However, we found no correlation between body condition and home range size. In fact, snakes inhabiting the two landscapes had equivalent body condition. These data suggest that snakes in the human-modified landscape have larger home ranges in order to find enough prey over the course of an active season. While the radiotelemetry data provided insight into the spatial ecology of Armenian Vipers in these two landscapes, we were also interested in examining their genetic diversity and population structure. We collected genetic samples from two locations within each of the two landscapes. At the local scale there was no significant differentiation between sampling locations, but on the regional scale we found the two geographically separated populations to be significantly differentiated from one another. The focus of conservation efforts for the Armenian Viper in altered habitat should be on maintaining corridors with high quality habitat that allow for seasonal movements, shelter, foraging and gene flow. Due to the strong genetic differentiation between the two populations we also recommend that regional populations be managed as independent conservation units.
Download or read book The Effect of Abiotic and Genetic Constraints on Demographic Persistence Limiting Species Ranges in Endemic Species written by Andrea Lorraine Dixon and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Taken together, this work advances our understanding of the evolutionary processes underlying population responses to ecological constraints. These processes explain not only how species ranges are currently shaped but help predict how species will respond to a changing climate.
Download or read book Genetics of Speciation written by David L. Jameson and published by . This book was released on 1977 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nature of populations, races, subspecies, and species. Genetic basis of isolation. Origin of isolation - theoretical. Origin of isolation - experimental. The nature of the speciation process.
