[PDF] Genetic Diversity In Spotted Turtle Populations eBook

Author : Maeghan L. Ciampa
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Page : 116 pages
File Size : 20,4 MB
Release : 2011
Category : Clemmys guttata
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The spotted turtle (Clemmys guttata) is a small, semiaquatic species that has been listed as a species of special concern in Massachusetts. Populations of the species on Nantucket Island exist in fragmented and possibly isolated populations, although the effect of this fragmentation on current population structure is unknown. This study attempted to look at the population structure of two populations, one from the Medouie Creek Wetland Complex on Nantucket Island and a mainland population from Halifax, MA. Microsatellite loci were examined to analyze the population genetics and compare two populations. Seven microsatellite loci were analyzed in 40 spotted turtles sampled from Nantucket Island and 10 turtles from Halifax. The seven microsatellite loci were found to be highly polymorphic. A total number of 92 alleles were found across all loci, with the number of alleles per locus ranging from seven to sixteen. Using various statistical tests, the multilocus genotypes of individuals in both populations were analyzed to determine population structure. Both populations were found to be i Hardy-Weinberg and linkage equilibrium and highly significant genetic variation was found within and between the Nantucket and Halifax populations. Private alleles were found in both populations across all microsatellite loci and analysis of these alleles indicates some loss of genetic diversity in the Nantucket Island population. Overall, the results of this study were used to classify the Nantucket Island and Halifax, MA populations as genetically distinct from each other and that all individuals sampled belong to two genetic clusters that correlate to geographic population assignment. These data suggest that the two populations should be regarded as distinct management units.

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Page : 0 pages
File Size : 18,80 MB
Release : 2015
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Turtles (order Testudines) are an ancient but highly threatened vertebrate group. Successful preservation of biodiversity in this group (as in others) requires identification of current threats, species-level traits that modulate vulnerability to these threats, and both general and species-specific strategies for mitigating threats. In this dissertation, I address these research needs for several Wisconsin turtles, focusing on the UCN-Endangered Blanding's turtle (Emydoidea blandingii). The approaches used here encompass multiple spatial scales, combine genetic and demographic methods of characterizing population viability and spatial ecology, and utilize comparisons among species, specifically by comparing endangered Blanding's turtles with more common co-occurring painted turtles (Chrysemys picta) and snapping turtles (Chelydra serpentina). Each chapter of this dissertation is written and formatted as a manuscript for publication in a scholarly journal. Chapter 1 (published in Diversity and Distributions) investigates the population-level demographic and genetic responses of three turtle species with differing habitat preferences and life histories to roads and climate. Chapter 2 (prepared for submission to Molecular Ecology) describes the effects of past and present landscape features on population genetic structure in this same suite of turtle species. Chapter 3 (submitted to Methods in Ecology and Evolution) develops a novel method for estimating dispersal rates from genetic kinship data and uses this method to investigate the spatial ecology of nesting female Blanding's turtles. Finally, Chapter 4 (submitted to Biological Conservation) deals with the demographic response of a population of Blanding's turtles to habitat restoration. Overall, the work collected here demonstrates how differences in species' life history traits and habitat preferences can affect their vulnerability to environmental change and suggests how strategies for managing populations and genetic diversity can be tailored to these traits.

Author : Sarah Holland Stephens
Publisher :
Page : pages
File Size : 27,88 MB
Release : 2003
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The critically endangered Kemp's ridley sea turtle experienced a dramatic decline in population size (demographic bottleneck) between 1947 and 1987 from 160,000 mature individuals to less than 5000. Demographic bottlenecks can cause genetic bottlenecks where significant losses of genetic diversity occur through genetic drift. The loss of genetic diversity can lower fitness through the random loss of adaptive alleles and through an increase in the expression of deleterious alleles. Molecular genetic studies on endangered species require collecting tissue using non-invasive or minimally invasive techniques. Such sampling techniques are well developed for birds and mammals, but not for sea turtles. The first objective was to explore the relative success of several minimally invasive tissue-sampling methods as source of DNA from Kemp's ridley sea turtles. Tissue sampling techniques included; blood, cheek swabs, cloacal swabs, carapace scrapings, and a minimally invasive tissue biopsy of the hind flipper. Single copy nuclear DNA loci were PCR amplified with turtle-specific primers. Blood tissue provided the best DNA extractions. Additionally, archival plasma samples are shown to be good sources of DNA. However, when dealing with hatchlings or very small individuals in field situations, the tissue biopsy of the hind flipper is the preferred method. This study's main focus was to evaluate whether the Kemp's ridley sea turtle sustained a measurable loss of genetic variation resulting from the demographic bottleneck. To achieve this goal, three alternative approaches were used to detect a reduction in Kemp's ridley's effective population size (Ne) from microsatellite data. These approaches were 1) Temporal change in allele frequencies, 2) An excess of heterozygotes in progeny, and 3) A mean ratio (M) of the number of alleles (k) to the range of allele size (r). DNA samples were obtained from Kemp's ridleys caught in the wild. PCR was used to amplify eight microsatellite loci and allele frequencies were determined. Data from only four microsatellites could be used. Although the reduced number of loci was a limiting factor in this study, the results of all three approaches suggest that Kemp's ridley sustained a measurable loss of genetic variation due to the demographic bottleneck.