Landscape Genetics of the Small-mouthed Salamander (Ambystoma Texanum) in a Fragmented Habitat PDF Download
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Author: Elizabeth Anne Rhoads
Publisher:
ISBN:
Category : Ambystomatidae
Languages : en
Pages : 102
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Habitat loss is the leading cause of species declines and extinctions worldwide. Fragmentation of original habitat into patches often accompanies habitat loss and spatially separates breeding populations across a landscape. Habitat fragmentation poses additional challenges for species by degrading habitat quality, altering population abundance and density, and decreasing gene flow among breeding populations in separate patches. Wetland loss and deforestation in western Ohio has fragmented both breeding and terrestrial habitat for woodland amphibians, where agriculture is now the dominant landuse. This project utilized genetic markers to study the effect of habitat fragmentation on the population structure of a woodland amphibian, the small-mouthed salamander (Ambystoma texanum), in Hardin County, Ohio. This species breeds in vernal pools within forest patches, and has low vagility. It was hypothesized that salamanders were not migrating between forest patches; and that populations in different forest patches would show genetic differentiation and small populations would have decreased genetic diversity. A method was developed to screen for unisexual Ambystoma salamanders, which also reproduce in vernal pools in the study area and whose larvae are difficult to distinguish from A. texanum larvae. For the population genetic analysis, a total of 160 A. texanum from eight breeding populations in five forest patches were genotyped for eight highly polymorphic microsatellite loci. The results indicate that all sampled populations have within-population structure, with the two most isolated populations having the highest inbreeding coefficients. Estimates of historical migration rates reveal that gene flow occurred in the past among sites that today show genetic differentiation. Overall our results suggest that forest fragmentation and wetland loss have reduced the connectivity of breeding populations, which supports numerous studies that implicate landscape change as the main threat to species decline.
Author: Elizabeth Anne Rhoads
Publisher:
ISBN:
Category : Ambystomatidae
Languages : en
Pages : 102
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Book Description
Habitat loss is the leading cause of species declines and extinctions worldwide. Fragmentation of original habitat into patches often accompanies habitat loss and spatially separates breeding populations across a landscape. Habitat fragmentation poses additional challenges for species by degrading habitat quality, altering population abundance and density, and decreasing gene flow among breeding populations in separate patches. Wetland loss and deforestation in western Ohio has fragmented both breeding and terrestrial habitat for woodland amphibians, where agriculture is now the dominant landuse. This project utilized genetic markers to study the effect of habitat fragmentation on the population structure of a woodland amphibian, the small-mouthed salamander (Ambystoma texanum), in Hardin County, Ohio. This species breeds in vernal pools within forest patches, and has low vagility. It was hypothesized that salamanders were not migrating between forest patches; and that populations in different forest patches would show genetic differentiation and small populations would have decreased genetic diversity. A method was developed to screen for unisexual Ambystoma salamanders, which also reproduce in vernal pools in the study area and whose larvae are difficult to distinguish from A. texanum larvae. For the population genetic analysis, a total of 160 A. texanum from eight breeding populations in five forest patches were genotyped for eight highly polymorphic microsatellite loci. The results indicate that all sampled populations have within-population structure, with the two most isolated populations having the highest inbreeding coefficients. Estimates of historical migration rates reveal that gene flow occurred in the past among sites that today show genetic differentiation. Overall our results suggest that forest fragmentation and wetland loss have reduced the connectivity of breeding populations, which supports numerous studies that implicate landscape change as the main threat to species decline.
Author: Joseph E. Bartoszek
Publisher:
ISBN:
Category : Ambystomatidae
Languages : en
Pages : 173
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It is generally recognized that amphibian populations declining across the globe. Habitat loss is the primary cause of decline. The salamander family Ambystomatidae has experienced significantly more rapid decline than the average for amphibians. Coefficients of Conservatism (CoC) have been developed for amphibians in Ohio. These are based primarily on habitat requirements with high CoCs for amphibians with stringent habitat requirements (e.g. vernal pools associated with large, intact, undisturbed forest), and low CoCs for amphibians with less stringent habitat requirements. Genetic diversity in five species and one hybrid complex of ambystomatid salamander in southwest Ohio were examined and compared to their respective CoC. Less gene flow across inhospitable habitat and consequently lower genetic diversity in that species would be expected compared with a species with less restrictive habitat requirements, i.e. a lower CoC. Microsatellites were used to determine conformation to Hardy Weinberg Equilibrium expectations, allelic and genotypic differences between populations, and inbreeding coefficients Fis and Fst. Genetic differences between woodlots and between ponds within a woodlot were examined. It was found that, for different species in the same habitat, species with higher CoCs have lower genetic diversity than species with lower CoCs. It was also found that habitat quality influences genetic diversity in all species. In some habitats, the genetic diversity of all species in that habitat will be lower than that of the same species in a more suitable habitat. In some cases presence of the hybrid complex (kleptogens) appears to have negatively impacted species that act as a sperm donor to the hybrid complex. In some species (e.g. smallmouth salamanders) genetic structure can be seen in different ponds within a woodlot. In other species (e.g. tiger salamanders) no such structure appears. It was also found that a railroad track acts as a barrier to marbled salamanders creating two genetically distinct populations. It was found that maternal ancestor of the kleptogens, A. barbouri, also acts as a sperm donor but does not replace the A. laterale genome in the nucleus. In addition to species specific differences in genetic diversity, habitat quality, and presence of kleptogens also influence genetic diversity in ambystomatid salamanders.
Author: Stephen Spear
Publisher:
ISBN:
Category : Microsatellites (Genetics)
Languages : en
Pages : 12
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The field of landscape genetics has great potential to identify habitat features that influence population genetic structure. To identify landscape correlates of genetic differentiation in a quantitative fashion, we developed a novel approach using geographical information systems analysis. We present data on blotched tiger salamanders (Ambystoma tigrinum melanostictum) from 10 sites across the northern range of Yellowstone National Park in Montana and Wyoming, USA. We used eight microsatellite loci to analyse population genetic structure. We tested whether landscape variables, including topographical distance, elevation, wetland likelihood, cover type and number of river and stream crossings, were correlated with genetic subdivision (FST ). We then compared five hypothetical dispersal routes with a straight-line distance model using two approaches: (i) partial Mantel tests using Akaike?s information criterion scores to evaluate model robustness and (ii) the BIOENV procedure, which uses a Spearman rank correlation to determine the combination of environmental variables that best fits the genetic data. Overall, gene flow appears highly restricted among sites, with a global FST of 0.24. While there is a significant isolation-bydistance pattern, incorporating landscape variables substantially improved the fit of the model (from an r2 of 0.3 to 0.8) explaining genetic differentiation. It appears that gene flow follows a straight-line topographic route, with river crossings and open shrub habitat correlated with lower FST and thus, decreased differentiation, while distance and elevation difference appear to increase differentiation. This study demonstrates a general approach that can be used to determine the influence of landscape variables on population genetic structure.
Author: Robert G. Weck
Publisher:
ISBN:
Category :
Languages : en
Pages : 62
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Author: James P. Bogart
Publisher:
ISBN: 9780660055480
Category : Ambystoma
Languages : en
Pages : 61
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"[The small-mouthed Salamander dependent population] exist only on one isolated island in Canada (Pelee Island in Lake Erie) and depend on an endangered sperm donor species, Small-mouthed Salamander (Ambystoma texanum), for recruitment. The salamander faces numerous threats that make its continued existence precarious. These include predation and habitat modification by introduced wild turkeys, drainage activities that can cause premature drying of breeding ponds, road mortality during seasonal migrations, urban development, and recreational activities. [The Jefferson Salamander dependent population] occupy restricted areas within populated and highly modified areas of Ontario and depend on an endangered sperm donor species, Jefferson Salamander (Ambystoma jeffersonianum), for recruitment. The salamander faces numerous threats from human activities, leading to habitat loss and fragmentation, making its continued existence precarious. [The Blue-spotted Salamander dependent population] depend on a sperm-donor species, Blue-spotted Salamander (Ambystoma laterale), that has an extensive distribution in Canada. It is found from Nova Scotia to Manitoba and from the Great Lakes to James Bay and Northern Quebec. Unisexuals that depend on this species have been identified in sites across this range and likely exist in many other sites that have not been subjected to genetic analyses. While declines have been observed and are expected for the Blue-spotted Salamander and unisexuals that depend on it in southwestern Ontario, threats are localized and expected to have little effect on the entire Canadian population"--Reasons for designation, p. iii.
Author: James Walker Petranka
Publisher:
ISBN:
Category : Ambystomatidae
Languages : en
Pages : 474
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Author: Wesley Keith Savage
Publisher:
ISBN:
Category :
Languages : en
Pages : 414
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Presents Ambystoma texanum, the smallmouth salamander, provided by Texas Memorial Museum of the University of Texas at Austin. Includes a photograph of the salamander and discusses the salamander's size, color, habitat, behavior, breeding, and range in Texas.
Author: Michael Paul Graziano
Publisher:
ISBN: 9781109712162
Category : Ambystoma
Languages : en
Pages : 154
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Author: Stacey Diane Summitt
Publisher:
ISBN:
Category : Gene flow
Languages : en
Pages : 50
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