Regional Population Structure of Spotted Salamanders (Ambystoma Maculatum) in a Fragmented Landscape PDF Download
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Author: Jennifer Lyn Purrenhage
Publisher:
ISBN:
Category : Spotted salamander
Languages : en
Pages : 60
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Author: Jennifer Lyn Purrenhage
Publisher:
ISBN:
Category : Spotted salamander
Languages : en
Pages : 60
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Book Description
Author:
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ISBN:
Category :
Languages : en
Pages :
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Author: Samara T. Eaton
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Category :
Languages : en
Pages :
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I examine the effects of landscape structure on the incidence and abundance of yellow-spotted salamanders, Ambystoma maculatum, and use these population level responses as indirect measures of movement. Two surveys of breeding populations in ponds located in a heterogeneous landscape were conducted and effects of landscape structure assessed at multiple spatial scales. Landscape structure was quantified as the proportion of forest and the total length of roads surrounding ponds. Additionally, the movement capabilities of juvenile A. maculatum in different habitat types was explored. Through the first survey I show that the proportion of forest influences incidence and density at a small spatial scale (100 m). I conclude that the breeding and post-breeding migration movements are influenced by the amount of forest and identify 15% forest, within 100 m of the pond, as a threshold amount of forest below which A. maculatum cannot persist at a pond. Results from a second survey, which encompassed a greater number of ponds at broader spatial scales, concur with the previous survey for the small scale effects of the proportion of forest, however, there is a significant effect of the proportion of forest at a broad spatial scale (1000 m). This provides indication that populations are spatially structured and that the amount of forest increases the connectivity of the landscape for A. maculatum. Also, at small spatial scales the total amount of road has a negative effect on incidence and abundance. Experimentally I assess the rates of movement of juveniles in forested and field habitat. Results show that juveniles can move faster in field habitat than forest. Finally, I explore the possibilities of harmonic radar as a new technique for tracking juvenile A. maculatum.
Author: Caroline G. Letourneau
Publisher:
ISBN:
Category : Genetic markers
Languages : en
Pages : 100
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The spotted salamander (Ambystoma maculatum) is an aggregate breeding amphibian that is dependent upon vernal pools for its reproductive life cycle. However, as wetland habitats become increasingly fragmented as the result of human activity, populations of A. maculatum may become progressively isolated from one another. Such isolation can impact the genetic variation of a population and thus pose challenges to its long term survival. This study used nine microsatellite loci to determine the levels of heterozygosity and the effective population size (Ne) of a population of spotted salamanders (Ambystoma maculatum) located at Wheaton College in Norton, Massachusetts. The mean observed heterozygosity was calculated as 0.59, which is similar to estimates of other A. maculatum populations, and Ne was estimated between 42 and 60 individuals. These values suggest that the Wheaton College vernal pool population of A. maculatum is genetically stable in the short term.
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: Scott A. Thomas
Publisher:
ISBN:
Category : Biology
Languages : en
Pages : 28
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The fine-scale genetic structure of populations is traditionally thought to be shaped primarily by geographic barriers to reproduction among local populations. However, other mechanisms of isolation have been recognized, but little has been done to determine their relative roles in shaping genetic variation in natural populations. In this study, I test whether genetic structure within and among breeding ponds of spotted salamanders (Ambystoma maculatum) is influenced by within-pond variation in breeding time. I found significant genetic structure attributable to variation in breeding time within ponds. This temporal structure was not consistent across ponds, indicating it is a local and not a regional effect. However, this temporal structure did not fully resolve strong patterns of inbreeding within ponds, indicating that reproductive barriers operating with in ponds are more effective than either spatial or phenological ones. Together, these findings reveal complex relationships between genetic structure and variation in breeding phenology that would not be uncovered by spatial or temporal analyses alone.
Author: Christopher A. Phillips
Publisher:
ISBN:
Category : Breeding
Languages : en
Pages : 238
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Author: Peter Cornell Jr Trenham
Publisher:
ISBN:
Category :
Languages : en
Pages : 218
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Author: Lloyd R. Gamble
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Category : Animal populations
Languages : en
Pages : 150
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Author: Ashley Lynn Nussbaum
Publisher:
ISBN:
Category :
Languages : en
Pages : 78
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