Spatial Variation in the Abundance, Demography, and Physiology of the Montane Endemic Salamander, Plethodon Shermani, and the Consequences of Climate Change

Spatial Variation in the Abundance, Demography, and Physiology of the Montane Endemic Salamander, Plethodon Shermani, and the Consequences of Climate Change
Author: Meaghan R. Gade
Publisher:
Total Pages:
Release: 2021
Genre: Climatic changes
ISBN:

As climate change marches on, it is imperative to understand how species respond via distribution, abundance, physiology, and behavior to their environment present-day in order to inform possible responses in the future. Populations of species exist across heterogeneous environments that may differentially influence particular responses. The scale at which these responses are assessed must be considered because patterns can emerge at a local scale that may not be detectable at broader scales. Yet, only assessing local-scale patterns and responses neglects the broader landscape patterns that ultimately shape fine-scales. Montane biodiversity experience extreme abiotic variation over small spatial scales. To increase our understanding of how these gradients influence wildlife across scales, my research examines the patterns of distribution, abundance, demographic life-history traits, behavior, and physiology in the red-legged salamander, Plethodon shermani, across multiple abiotic gradients in the Southern Appalachian Mountains. The primary objectives of my research are to (1) understand the effects of spatial patterns on ecological responses of P. shermani and (2) use that knowledge to predict how responses will change in the future. Terrestrial Plethodon salamanders lack lungs and depend on cool and moist microhabitat to facilitate gas exchange across their skin surface. As such, salamanders are restricted to specific habitats. We know that salamander abundance increases with elevation due to the cool and moist regional climate at high elevations. However, my research investigates the role of both elevation and stream distance gradients as broad and fine-scale abiotic gradients, respectively, that salamanders may be responding. Although low elevations are regionally warm and dry, microhabitats near streams are buffered and tend to be cooler and wetter. I found that salamander distribution and abundance track these landscape patterns such that at low elevations, animals are distributed in their highest abundance near stream sides but become less dependent on stream-side habitat at high elevations due to the regionally cool and moist habitat. Salamander life history also varies across these gradients; survival decreases with elevation but reproductive rates and growth increase with elevation. Both survival and reproduction decrease with stream distance at low elevations, but growth and movement increase with stream distance. I also found that a metric for stress, dermal Corticosterone, (dCORT) was lowest in animals at low elevations and stream distance had no effect. Salamander dCORT additively increased in response to experimental conditions reflective of future climate change. I also found that the surface activity probability of salamanders will likely increase in the future in response to rising temperatures. Using a highly integrative approach, my research collectively shows that salamanders have multi-faceted responses to spatial variation of landscapes and will be impacted by future climate change.

Population Dynamics and Range Limits of a Montane Salamander

Population Dynamics and Range Limits of a Montane Salamander
Author: Nicholas Caruso
Publisher:
Total Pages: 400
Release: 2017
Genre:
ISBN:

Understanding the abiotic and biotic factors that determine the limits to species' ranges is an essential goal in ecology, biogeography, evolutionary biology, and conservation biology. The abiotic environment, specifically climate, can influence amphibian life history in a variety of ways; populations in cooler temperatures tend to have shorter breeding seasons, fewer clutches, slower growth rates, but larger body size, older age at maturity, greater number of eggs within a clutch and larger eggs. However, for many salamander species the relationship between demographic vital rates (i.e., survival, growth, and reproduction) and climate is unknown. As future changes in climate will likely have a negative effect on many populations, especially salamanders within the southern Appalachians, understanding how the environment can influence life history and vital rates, and subsequently population growth, is crucial to predicting how future changes in climate will affect populations. This dissertation focuses on a montane endemic salamander, Plethodon montanus, to understand how vital rates vary along an elevational (climatic) gradient, the relative importance of the abiotic environment and local adaptation on vital rates, and lastly how the observed variation in vital rates ultimately affects population growth. These studies are important to understanding how future climate changes may affect montane salamanders, especially since environmental suitability is predicted to decrease throughout the southern Appalachians and notably at lower elevations for P. montanus. Survival and growth were both largely influenced by climate: populations at higher elevations had higher survival, larger asymptotic size, older individuals, and reached maturity at an older age compared to lower elevations. At lower elevations, survival of large females was the most important vital rate based on elasticity analyses and best predicted population growth rates, whereas the remaining vital rates showed little importance. However at higher elevations, while survival of large females had the highest elasticity, three vital rates corresponding to survival during earlier life stages had higher predictability of population growth. Moreover, higher elevations were marked by having vital rates with more evenly distributed importance as measured by elasticity compared to lower elevations, which likely put lower elevation habitats at a greater threat from environmental stochasticity as low elasticity evenness is associated with greater likelihood of declines from increased variation in the environment. This work addresses the role of the abiotic environment (e.g., elevation, climate) on life history and demographic vital rates. The future appears bleak for the focal species and likely other montane terrestrial plethodontids under projected changes in climate.

Individual, Population and Landscape-scale Effects of Timber Harvest on the Red-legged Salamander (Plethodon Shermani)

Individual, Population and Landscape-scale Effects of Timber Harvest on the Red-legged Salamander (Plethodon Shermani)
Author: Grant McClintock Connette
Publisher:
Total Pages:
Release: 2014
Genre: Electronic dissertations
ISBN:

Habitat loss and alteration are widely recognized as major threats to global biodiversity and the vulnerability of animal species to these disturbance processes can depend on the behavioral responses of individuals to modified landscapes. In response to a changing environment, individuals may either attempt to adapt to changing conditions or disperse to new habitat. At the local scale, the emigration of individuals or changes in activity patterns could lead to reduced counts of animals in ecological studies. At broader spatial scales, organismal movement may enable population rescue or reestablishment after disturbance and maintain demographic connectivity among populations. These complex mechanisms underlying the perceived abundance and distribution of species often requires a careful deconstructing of demographic trends and sampling variation in ecological data. Lungless salamanders (Family Plethodontidae) are extremely abundant in many forest and headwater stream ecosystems of eastern North America. These salamanders breathe across their moist skin surface, making them sensitive to fluctuations in temperature and moisture conditions. Thus, changes in habitat characteristics are known to have a considerable effect on populations of these salamanders. However, studies identifying the behavioral or demographic causes of declines as well as patterns of long-term recovery are critically needed. My dissertation research combined behavioral, population and landscape-scale studies to identify the effects of timber harvest on a lungless woodland salamander (Plethodon shermani). The primary objectives of my research were to 1) to describe the short-and long-term effects of timber harvest on salamander abundance and 2) to determine the behavioral or demographic processes dictating the abundance and distribution of salamanders at both local and landscape scales. To characterize baseline population dynamics of the salamander, P. shermani, I conducted a 5-year capture-mark-recapture study which revealed substantial annual variation in survival, recruitment, and population size under natural conditions. Initial results suggest that differences in recruitment and over-winter survival might be responsible for the lower abundances of terrestrial salamanders in logged areas at the end of this study. In an experimental translocation of salamanders into a timber cut and nearby forest habitat, I found that salamanders respond to differences in habitat quality by altering their movement behavior. This type of behavioral shift might help mitigate the risk of sustaining activity in recently logged forest. In an additional study, I tracked salamanders using a PIT-tag telemetry system in order to identify mortality, rather than emigration or reduced activity, as the likely cause for perceived declines in salamanders immediately following timber harvest. Finally, in a series of landscape-scale surveys, I found that salamander abundance was positively correlated with forest age (i.e., years since harvest), that full population recovery can require greater than 100 years, and that populations of species with greater movement ability may recover faster due to immigration of individuals from surrounding forest. Collectively, these studies identify key behavioral and demographic processes responsible for observed changes in salamander populations and suggest specific strategies for conservation and management.

Using Quantitative Approaches to Estimate Space-use, Population Dynamics, Behavior, and Climate Change Adaptive Potential for the Red-backed Salamander Plethodon Cinereus

Using Quantitative Approaches to Estimate Space-use, Population Dynamics, Behavior, and Climate Change Adaptive Potential for the Red-backed Salamander Plethodon Cinereus
Author: David Munoz
Publisher:
Total Pages:
Release: 2015
Genre:
ISBN:

The red-backed salamander, Plethodon cinereus, is a common woodland amphibian that is found throughout much of eastern North America. The species is important to forest ecological processes, and changes in their population density are often used to measure the impacts of forest management, pollution, and environmental change. Therefore, consistent methods of density estimation are required. In the first chapter, I review spatial capture-recapture, a modern modeling tool that incorporates spatial information to reliably estimate population density without the need for the ad-hoc methods that render other density estimates incomparable. It can also be used to make inferences on space-use, population dynamics, and connectivity. I then demonstrate the versatility of spatial capture-recapture using P. cinereus mark-recapture data collected from my study sites in central Pennsylvania. For the second chapter of this thesis, I use spatial capture-recapture and other modeling approaches to test hypotheses about P. cinereus climate change adaptive capacity. This salamander is a convenient model for understanding dispersal-limited species, so I tested eight hypotheses to see how behavioral plasticity and fitness were affected by climate variability. Based on previous evidence, I also tested whether a common color polymorphism is a useful visual cue for predicting within-population variation in climate tolerances. Using four years of mark-recapture information from Maryland, I found the color morph is not a useful indicator, but overall, the population did show strong climate preferences, indicating that population persistence could be threatened by warmer and drier conditions predicted in the future.

Factors Affecting Abundance, Physiology, and Fine-scale Genetic Differentiation of the Western Slimy Salamander (Plethodon Albagula)

Factors Affecting Abundance, Physiology, and Fine-scale Genetic Differentiation of the Western Slimy Salamander (Plethodon Albagula)
Author: William Earl Peterman
Publisher:
Total Pages: 95
Release: 2013
Genre: Electronic dissertations
ISBN:

Inferring process from pattern can be a challenging undertaking when dealing with ecological complexity. The distribution and abundance of organisms on the landscape is often interpreted through the lens of competition, movement, or physiology, as well as interactions with the abiotic environment. Further, movement, distribution, and abundance often coincide with favorable abiotic environments such as temperature, moisture, or nutrients. At its core, landscape genetics seeks to identify the spatial processes shaping the observed patterns of genetic diversity across the landscape, but most landscape genetic studies are predominantly exploratory and lack well-established hypotheses. To increase understanding of process-driven patterns in landscape genetics, I studied the western slimy salamander (Plethodon albagula) in east-central Missouri with three specific questions: (1) Where are salamanders on the landscape, and what environmental factors influence local abundance? (2) Is there a physiological constraint underlying the observed patterns of distribution and abundance? (3) How is spatial genetic structure shaped by abundance and physiology across the landscape? I utilized a combination of abundance modeling, spatial quantification of water loss using plaster of Paris models, and landscape genetics analyses to assess the factors contributing to genetic differentiation across a 1300 ha landscape. Plethodontid salamanders are highly sensitive to water loss, in part due to their lack of lungs and cutaneous respiration. I found that abundance of salamanders was best predicted by canopy cover, topographic position (ridge, slope, ravine), and the interaction between wetness and solar exposure. The spatial relationships of these factors are such that abundance is predicted to be highest in forested ravines with lower solar exposure. Plaster models deployed across the landscape served as surrogates for live salamanders to quantify rates of water loss. I found that rates of water loss across the landscape were inversely related to predicted abundance, suggesting that water loss is likely a physiologically-limiting process underlying the distribution of salamanders. Finally, I determined that genetic distances were significantly correlated with ecological surfaces, and that the independent landscape features underlying these processes were poor predictors of genetic differentiation. My results highlight the importance of understanding basic ecological and physiological factors as mechanisms for interpreting spatial genetic patterns.

Modeling the Effects of Precipitation on Salamander Demography for Conservation Planning

Modeling the Effects of Precipitation on Salamander Demography for Conservation Planning
Author: Jillian Sloper Howard
Publisher:
Total Pages: 354
Release: 2018
Genre:
ISBN:

Integrative conservation recognizes that conservation of natural resources is a complex process because most, if not all, systems are coupled human and natural systems. Conservation planning requires conceptual tools that transcend disciplines and understanding of the ecological and human aspects of a system. For example, Southern Appalachia is a region of exceptional biodiversity which provides a number of ecosystem services within and across the broader southeastern United States. It is also a rapidly exurbanizing landscape with associated cultural and social pressures and is expected to experience significant climate change in the future. A key issue in this region is increasing residential development on steep mountain slopes and how it will impact social and economic development, public safety, and the integrity of terrestrial and aquatic ecosystems. In order for communities to conserve and manage their natural systems, we need rigorous models to identify and prioritize areas of high current and future suitability for sensitive taxa. However, for many of those species, we lack the rigorous demographic data needed for such models. At the same time, we must have an understanding of local stakeholder perspectives and values regarding issues like steep slope development that may affect conservation priorities. In this dissertation, I address these needs in the context of salamander ecology and conservation. First, I conducted a literature review to assess current knowledge of demographic rates available for parameterizing models of population dynamics for direct-developing North American salamanders in the family Plethodontidae. I determined that some rates, such as clutch size and frequency are well-documented and reasonably transferrable across species, but there are very few published estimates of survival, and nearly half of those published rates may not be realistic despite being estimated from field data. I found that there were few expected patterns in estimated survival rates among methodologies or environments that could be used to predict variation in survival among taxa and contexts from published studies. Next, I developed a Bayesian model for an eight-year robust design, capture-mark-recapture dataset of Plethodon in the Coweeta Basin in western North Carolina to estimate salamander survival rates and their sensitivity to precipitation. I used several hundred observations of live and preserved mature female salamanders to develop a novel algorithm to estimate final clutch size from ovarian follicle counts made at different points in the female reproductive cycle. I also used N-mixture models of repeated counts of salamanders across a spatial precipitation gradient to estimate size-class specific abundance and reproductive rates as a function of mean annual precipitation. I used the survival and reproductive rate estimates to project salamander population growth across the extent of the Coweeta Basin and Macon County, North Carolina, under current [past 30 years] climate and future drought frequency and severity scenarios. Model projections suggest that only a small proportion of the region likely supports consistent positive salamander population growth. Many areas occupied by salamanders likely have limited abundance and depend on limited source habitats such as coves to support local salamander populations. Finally, I used archival research, targeted interviews and participatory mapping to identify the primary concerns of stakeholders in Macon County regarding the regional environment and forest land use. I found that people are generally concerned about steep slope development, but their primary focus is on the economic impacts and regulation of development, not on its ecological impacts. These local priorities differ from the foci of scientists working in the region who are primarily concerned with impacts of steep slope development on biodiversity and natural resources. Nonetheless, while artifacts suggest a non-ecological focus on steep slope development, participants in the mapping study consistently placed conservation land use priorities at higher elevations than development priorities, suggesting some intrinsic connection between steep slopes and conservation. A combined, spatially-explicit map of stakeholder land use priorities and projected salamander population growth rates identified consistencies between areas people prioritized for conservation and areas likely to sustain salamander populations under current and future precipitation scenarios.

Principles and Methods in Landscape Ecology

Principles and Methods in Landscape Ecology
Author: Almo Farina
Publisher: Springer Science & Business Media
Total Pages: 412
Release: 2008-01-22
Genre: Science
ISBN: 1402055358

Landscape ecology is an integrative and multi-disciplinary science and Principles and Methods in Landscape Ecology reconciles the geological, botanical, zoological and human perspectives. In particular ,new paradigms and theories such as percolation, metapopulation, hierarchies, source-sink models have been integrated in this last edition with the recent theories on bio-complexity, information and cognitive sciences. Methods for studying landscape ecology are covered including spatial geometry models and remote sensing in order to create confidence toward techniques and approaches that require a high experience and long-time dedication. Principles and Methods in Landscape Ecology is a textbook useful to present the landscape in a multi-vision perspective for undergraduate and graduate students of biology, ecology, geography, forestry, agronomy, landscape architecture and planning. Sociology, economics, history, archaeology, anthropology, ecological psychology are some sciences that can benefit of the holistic vision offered by this texbook.

Ecological Responses to the 1980 Eruption of Mount St. Helens

Ecological Responses to the 1980 Eruption of Mount St. Helens
Author: Virginia H. Dale
Publisher: Springer Science & Business Media
Total Pages: 344
Release: 2006-01-16
Genre: Science
ISBN: 0387281509

The 1980 eruption of Mount St. Helens caused tragic loss of life and property, but also created a unique opportunity to study a huge disturbance of natural systems and their subsequent responses. This book synthesizes 25 years of ecological research into of volcanic activity, and shows what actually happens when a volcano erupts, what the immediate and long-term dangers are, and how life reasserts itself in the environment.

Amphibian Declines

Amphibian Declines
Author: Michael J. Lannoo
Publisher: Univ of California Press
Total Pages: 1124
Release: 2005-06-15
Genre: Nature
ISBN: 9780520235922

Documents in comprehensive detail a major environmental crisis: rapidly declining amphibian populations and the disturbing developmental problems that are increasingly prevalent within many amphibian species.

Chemical Signals in Vertebrates 11

Chemical Signals in Vertebrates 11
Author: Jane Hurst
Publisher: Springer Science & Business Media
Total Pages: 433
Release: 2007-10-26
Genre: Science
ISBN: 0387739459

This volume contains the proceedings of the conference of the same name held in July 2006 at the University of Chester in the United Kingdom. It includes all the latest research on chemical communication relevant to vertebrates, particularly focusing on new research since the last meeting in 2003. Topics covered include the chemical ecology, biochemistry, behavior, olfactory receptors, and the neurobiology of both the main olfactory and vomeronasal systems of vertebrates.