Author: Christopher A. Phillips
Publisher:
ISBN:
Category : Breeding
Languages : en
Pages : 238

Get Book Here

Book Description

Author: Peter Cornell Jr Trenham
Publisher:
ISBN:
Category :
Languages : en
Pages : 218

Get Book Here

Book Description

Author: Scott A. Thomas
Publisher:
ISBN:
Category : Biology
Languages : en
Pages : 28

Get Book Here

Book Description
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: Patrick Yamnik
Publisher:
ISBN:
Category :
Languages : en
Pages : 104

Get Book Here

Book Description
Abstract: Amphibian populations are experiencing rapid declines throughout the world that are apparently driven by habitat loss and fragmentation. Of particular concern is the rapid loss of wetland habitats which serve as critical breeding habitat for many amphibian species. For many species we don't really understand the habitat requirements for reproduction. Many wetlands, especially small isolated wetlands, are being lost and replace with mitigation wetlands that may not provide the same quality habitat as the natural wetlands they replace. The spotted salamander (Ambystoma maculatum) is a key example of an amphibian species that relies on small isolated wetlands for breeding habitat. Although the spotted salamander is not endangered, it can be used as a surrogate to study habitat availability and breeding behavior. The objective of this study is to determine what characteristics of wetlands are determinants of their use by spotted salamanders for breeding. I measured eight variables for 40 ponds at the University of Mississippi Biological Field Station during 2007, including pH, canopy cover, emergent vegetation, submerged vegetation, distance to the nearest forest, hydroperiod, fish abundance, and larval mole salamander (Ambystoma talpodideum) abundance. I then correlated these variables using Spearman rank correlations and non-metric multidimensional scaling with spotted salamander egg mass density and larval survival. Emergent vegetation, hydroperiod, and larval mole salamander abundance all appeared to be positively correlated with spotted salamander egg mass deposition and larval survival. Of these factors, emergent vegetation and hydroperiod are likely to be factors affecting site selection, while the positive correlation with the mole salamander abundance is likely due to similar breeding habitat preference by two species. Because the presence of emerge vegetation appeared to be the most significant factor driving egg mass deposition, I chose to manipulate this variable in 30 ponds for the 2008 breeding season. Ten ponds were placed into each of the following treatments: increased emergement vegetation, decreased emergent vegetation, and no manipulation of emergent vegetation to determine if salamanders would switch ponds to maximize reproductive success. There was no significant difference in the change of egg mass counts between years for the treatments. The lack of change was likely due to fidelity to the breeding pond by adult salamanders. This study suggest that emergent vegetation and hydroperiod are important pond characteristics assessed by spotted salamanders but that adult salamanders may continue to see ponds after the pond characteristics are altered. Censuses of spotted salamanders using egg mass counts may not be the most sensitive measure of environmental change due to strong breeding site fidelity.

Author: Nicholas Gervais
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
"Declines in amphibian populations have been noted since the late 1980's with many of the causes linked to habitat contamination and destruction by natural and anthropogenic sources. Amphibians with bi-phasic life histories have been thought to be particularly vulnerable to negative environmental conditions but there is much evidence of their resilience and capacity to survive in degraded or contaminated environments. Larval amphibians in small permanent or ephemeral ponds may be particularly vulnerable to altered environmental conditions and may face the greatest pressure to adapt. In Chapter 1, I briefly review the evidence of amphibian declines and how populations may adapt to and overcome assorted negative environmental factors. In Chapter 2, I investigated the phenomenon of adaptation in a particular circumstance. I collected Spotted Salamander (Ambystoma maculatum) egg masses from a population breeding in a naturally acidic pond called Bat Lake, as well as four other populations living in lakes closer to pH neutral. To determine if the salamanders were adapted to their particular breeding lakes, I used common garden experiments in the lab where I raised larvae from each of the lakes in the waters from all the other lakes, as well as their own and compared the survival rates, size at metamorphosis and time to metamorphosis. Bat Lake larvae grew larger and survived longer in their acidic native breeding pond water than in the waters of other lakes suggesting they are adapted to their native pond waters. The larvae from the other lake populations showed similar results and fared better in their native waters than in the Bat Lake water. Based on these results, in Chapter 3, I tested if pH, specifically, was causal. I raised larvae from the five populations in waters of different pH (4.0, 5.5, 7.0), reasoning that if the Bat Lake population was more adapted to the high acidity compared to the other populations, the larvae from Bat Lake should demonstrate higher fitness correlates at lower pH than larvae of other populations. In this experiment, the Bat Lake larvae survived longer and grew larger in the highly acidic water than did larvae from the other populations. My results are consistent with natural selection for tolerance of low pH conditions tolerance among Bat Lake Spotted Salamander larvae and indicate that the salamanders from Bat Lake potentially exhibit signs of local adaption to the highly acidic conditions in which they live. This study was unable, however to prove whether this adaptation was due to evolutionary change, phenotypic plasticity, maternal effects or some other unknown factor. " --

Author: Shannon Elisabeth Pittman
Publisher:
ISBN:
Category : Electronic Dissertations
Languages : en
Pages : 200

Get Book Here

Book Description
Human-induced habitat change is widely regarded as a primary factor threatening the persistence of species. One major consequence of habitat alteration is its effect on the movement behavior of individuals. Spotted salamanders (Ambystoma maculatum) are forest-dependent, pond-breeding amphibians. I used a combination of empirical studies of juvenile spotted salamander movement and individual-based modeling to investigate the influence of habitat amount and arrangement on juvenile salamander survival. Salamanders moved straighter and with fewer turns through field habitat compared to both forest and early successional habitat. Movement in forest was well approximated by a correlated random walk. Salamanders oriented movement toward forest when released at most 10 m from the forest edge. Different movement strategies were optimal under different habitat modification scenarios. The strength of movement bias toward habitat had a significant effect on the probability of individuals locating habitat. The degree to which movement bias affected the probability of locating habitat differed based on assumptions of habitat clumping and density-dependent mortality. My results indicated that the amount and configuration of habitat surrounding wetlands affect optimal movement behavior, and habitat managers should consider the configuration of habitat surrounding wetlands when designing conservation measures.

Author: Caroline G. Letourneau
Publisher:
ISBN:
Category : Genetic markers
Languages : en
Pages : 100

Get Book Here

Book Description
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

Get Book Here

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: Alistair Dawson
Publisher:
ISBN:
Category : Medical
Languages : en
Pages : 476

Get Book Here

Book Description
Provides a review of all aspects relating to hormones in birds, both wild and domestic. In this book, each chapter is written by leading researchers in the field from around the world and presents an in-depth and up-to-date review and analysis of the subject matter.