Understanding Amphibian Vulnerability to Extinction

Understanding Amphibian Vulnerability to Extinction
Author: Sarah J. Corey
Publisher:
Total Pages: 187
Release: 2009
Genre:
ISBN:

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Abstract: In the global extinction crisis currently underway, threats to biodiversity are not simply limited to species with particular risks in particular cases. Biodiversity will be increasingly affected by the wholesale decline of entire clades. In the face of this crisis, with amphibians ranking at the top of all vertebrates in the rate of extinctions, there is a great need for macroecological studies addressing three key areas of species declines. The processes that put species at great risk for extinction may be associated with 1) environmental factors, 2) spatially structured, or geographic effects, and 3) evolutionary predispositions to those processes (phylogenetic structure in vulnerability). I present a collection of work to address primarily the phylogenetic and geographic components of species vulnerability. First, I construct a theoretical foundation for using phylogenetic comparative methods for conservation assessments, emphasizing the importance of evolutionarily specific parameters and trees. I prescribe a greater conservation focus on understanding the severity of clade-level threats and potential data deficient species vulnerability, and identify evolutionary scenarios with the greatest return on resource investments. Second, I identify autocorrelated threats in the amphibian tree of life representing potential evolutionary predispositions to enigmatic rapid declines and Redlist threatened status in the superfamily Hyloidea. Third, I focus in on a family in Hyloidea, Hylidae, and use multiple phylogenetic comparative methods to identify phylogenetic signal in processes that selectively threaten lineages in the tree. I find phylogenetic signal (a predisposition to vulnerability) in pollution, habitat loss, species with multiple threatening processes, Redlist threatened status, and enigmatic rapid declines, concentrated in the clade Hylini. Among the comparative methods employed is a new application for conservation of a more flexible measure of phylogenetic signal accounting for selection using an Ornstein-Uhlenbeck model. Fourth, I use a landscape perspective to discover what spatial and environmental factors predict threats to amphibians in Venezuela. I find that traditional measures of human impact (population density and ecological footprint) effectively predict higher numbers of threatened amphibians, but indigenous peoples population density does not predict threats. Accounting for spatial dependence in the landscape reveals that cultural stewardship, i.e., parks on indigenous versus nonindigenous land, cannot predict threatened species distributions, failing to validate typical conservation concerns over indigenous population impacts to parks and biodiversity. Using a local spatial autocorrelation metric, I also find that the northwest region of Venezuela is a hotspot of geographic irreplaceability, for spatially autocorrelated threatened species, endemics and data deficient species. Overall, my collection of work addresses key themes in the amphibian extinction crisis using a macro-analytic approach: evolutionary predisposition to threats, anthropogenic threatening processes and spatial autocorrelation (or clumping) of threatened species. My work supports the emerging consensus that the extinction crisis is widespread, in terms of impact to phylogenetic diversity and geographic regions, but my findings also point to advantages for conservation policy and management gained by prioritizing vulnerable clades and geographic regions that stand to lose the most diversity and hold the greatest potential management payoffs.

Extinction in Our Times

Extinction in Our Times
Author: James P. Collins
Publisher: Oxford University Press
Total Pages: 442
Release: 2009-07-07
Genre: Science
ISBN: 0199886334

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For over 350 million years, thousands of species of amphibians have lived on earth, but since the 1990s they have been disappearing at an alarming rate, in many cases quite suddenly and mysteriously. What is causing these extinctions? What role do human actions play in them? What do they tell us about the overall state of biodiversity on the planet? In Extinction in Our Times, James Collins and Martha Crump explore these pressing questions and many others as they document the first modern extinction event across an entire vertebrate class, using global examples that range from the Sierra Nevada of California to the rainforests of Costa Rica and the Mediterranean coast of North Africa. Joining scientific rigor and vivid storytelling, this book is the first to use amphibian decline as a lens through which to see more clearly the larger story of climate change, conservation of biodiversity, and a host of profoundly important ecological, evolutionary, ethical, philosophical, and sociological issues.

The Evolutionary Origins of Amphibian Extinction Risk

The Evolutionary Origins of Amphibian Extinction Risk
Author: Daniel Greenberg
Publisher:
Total Pages: 150
Release: 2019
Genre:
ISBN:

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The rise of humanity to ecological dominance has precipitated concerted patterns of environmental change across every biome on Earth. Human activities can upend the adaptive landscapes on which species' have evolved, causing the sudden maladaptation of lineages to these novel conditions. Amphibians are amongst the most threatened vertebrates, with contemporary extinctions driven by multiple interacting stressors including habitat destruction, introduced pathogens, and climate change. Despite these looming threats, we understand little about how or why susceptibility to these stressors varies across amphibian lineages. In this thesis, I investigate the evolutionary origins of modern extinction risk in the Amphibia, by examining comparative patterns of susceptibility to various drivers of extinction. First, I show that modern extinction risk positively covaries with speciation rates across amphibian genera due to the most rapidly-diversifying clades producing numerous range-restricted and vulnerable species. Second, I demonstrate how evolutionary dynamics may influence local-scale extinction by examining amphibian species' responses to deforestation across the world. Contrary to patterns of global threat, the slowest-diversifying amphibian lineages are disproportionately lost from human-modified ecosystems - which may reflect a relationship between diversification and niche lability. Third, I examine phylogenetic and trait-based patterns of susceptibility to a human-dispersed fungal pathogen. Though species' ecology and life history consistently shape infection patterns across diverse amphibian assemblages, these traits appear to bear little weight for species' extinction risk from disease epidemics. Fourth, I test the relative effects of both dehydration and temperature on performance, and therefore climate risk, in three ecologically diverse anuran species. Performance was maintained across broad thresholds of dehydration in all species, but warmer temperatures accelerated the onset of performance decline. Species-specific biophysical modelling revealed stark differences in how dehydration is likely to limit activity in each species, suggesting that desiccation physiology may be an important driver of extinction risk from climate change in amphibians. These studies collectively illustrate that amphibian species' responses to anthropogenic environmental change have deep evolutionary roots. In turn, we can expect our continued environmental dominance to fundamentally reshape the evolutionary tree of amphibians into the future.

The Ecology and Behavior of Amphibians

The Ecology and Behavior of Amphibians
Author: Kentwood D. Wells
Publisher: University of Chicago Press
Total Pages: 1162
Release: 2010-02-15
Genre: Science
ISBN: 0226893332

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Consisting of more than six thousand species, amphibians are more diverse than mammals and are found on every continent save Antarctica. Despite the abundance and diversity of these animals, many aspects of the biology of amphibians remain unstudied or misunderstood. The Ecology and Behavior of Amphibians aims to fill this gap in the literature on this remarkable taxon. It is a celebration of the diversity of amphibian life and the ecological and behavioral adaptations that have made it a successful component of terrestrial and aquatic ecosystems. Synthesizing seventy years of research on amphibian biology, Kentwood D. Wells addresses all major areas of inquiry, including phylogeny, classification, and morphology; aspects of physiological ecology such as water and temperature relations, respiration, metabolism, and energetics; movements and orientation; communication and social behavior; reproduction and parental care; ecology and behavior of amphibian larvae and ecological aspects of metamorphosis; ecological impact of predation on amphibian populations and antipredator defenses; and aspects of amphibian community ecology. With an eye towards modern concerns, The Ecology and Behavior of Amphibians concludes with a chapter devoted to amphibian conservation. An unprecedented scholarly contribution to amphibian biology, this book is eagerly anticipated among specialists.

In the Light of Evolution

In the Light of Evolution
Author: National Academy of Sciences
Publisher: National Academies Press
Total Pages: 433
Release: 2017-01-01
Genre: Science
ISBN: 0309444225

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Biodiversity-the genetic variety of life-is an exuberant product of the evolutionary past, a vast human-supportive resource (aesthetic, intellectual, and material) of the present, and a rich legacy to cherish and preserve for the future. Two urgent challenges, and opportunities, for 21st-century science are to gain deeper insights into the evolutionary processes that foster biotic diversity, and to translate that understanding into workable solutions for the regional and global crises that biodiversity currently faces. A grasp of evolutionary principles and processes is important in other societal arenas as well, such as education, medicine, sociology, and other applied fields including agriculture, pharmacology, and biotechnology. The ramifications of evolutionary thought also extend into learned realms traditionally reserved for philosophy and religion. The central goal of the In the Light of Evolution (ILE) series is to promote the evolutionary sciences through state-of-the-art colloquia-in the series of Arthur M. Sackler colloquia sponsored by the National Academy of Sciences-and their published proceedings. Each installment explores evolutionary perspectives on a particular biological topic that is scientifically intriguing but also has special relevance to contemporary societal issues or challenges. This tenth and final edition of the In the Light of Evolution series focuses on recent developments in phylogeographic research and their relevance to past accomplishments and future research directions.

Amphibian Declines

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

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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.

Threatened Amphibians of the World

Threatened Amphibians of the World
Author: S. N. Stuart
Publisher:
Total Pages: 784
Release: 2008
Genre: Amphibians
ISBN:

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"Amphibians are facing an extinction crisis, but getting to the facts has been difficult. "Threatened Amphibians of the World" is a visual journey through the first-ever comprehensive assessment of the conservation status of the world's 6,000 known species of frogs, toads, salamanders, and caecilians. All 1,900 species known to be threatened with extinction are covered, including a description of threats to each species and an evaluation of conservation measures in place or needed. Each entry includes a photograph or illustration of the species where available, a distribution map, and detailed information on range, population and habitat and ecology. Introductory chapters present a detailed analysis of the results, complemented by a series of short essays written by many of the world's leading herpetologists. Appendices include annoted lists of lower risk species and a country-by-country listing of threatened amphibians."--pub. desc.

Amphibians in Decline

Amphibians in Decline
Author: David Martin Green
Publisher: Society for the Study of Amphibians & Reptiles
Total Pages: 364
Release: 1997
Genre: History
ISBN:

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The first volume of the series comprises the report to a task force of the World Conservation Union (IUCN) by a Canadian research group. The 29 papers include demographic and population studies, status reports, descriptions of methods, and studies or reviews of causes of amphibian declines. Among the suspected causes are pesticides, global change, ultraviolet radiation, and disease. An appendix describes the status of all 47 species of Canadian amphibians and includes photographs of most. Annotation copyrighted by Book News, Inc., Portland, OR

Assessing and Mitigating Risk to Amphibian Populations from Shifting Anthropogenic Stressors

Assessing and Mitigating Risk to Amphibian Populations from Shifting Anthropogenic Stressors
Author: Rylee Murray
Publisher:
Total Pages: 0
Release: 2023
Genre:
ISBN:

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Human disturbances to landscapes resulting in habitat degradation and fragmentation frequently drive wildlife population declines by altering demographic rates. A deep understanding of the specific mechanisms that reduce survival of individual life history stages, and the magnitude of the response, is critical to mitigating drivers of decline. I explore how a range of anthropogenic stressors scale to the level of emergent population dynamics using individual level physiological responses and stage-structured demographic models to improve predictions for three conservation challenges: 1) understanding impacts to amphibian populations affected by river hydropower development, 2) forecasting the magnitude and impact of climate change for populations of an amphibian whose range spans across 16o of latitude, and 3) identifying the impact and most effective mitigation strategies for amphibian populations subject to increasing road mortality. I use estimates of individual-level physiological traits to predict how anthropogenic changes in thermal habitat for Coastal tailed-frog (Ascaphus truei) will affect population-level vulnerability from 1) river diversion hydropower dams, and 2) accelerating climate change. I demonstrate that A. truei populations in British Columbia are subject to the equivalent of 50-years of climate warming in rivers where river diversion hydropower dams operate. I find that across the A. truei range, from Northern California to Northern British Columbia, that populations at the southern range boundary have higher immediate vulnerability to climate change. However, faster rates of temperature change in the north, compounded with adaptations to lower temperatures, causes accelerating risk to northern populations. Equally important to forecasting population vulnerability is identifying and evaluating methods to reverse population declines. I use demographic models to elucidate the potential for reducing extinction risk to migrating populations of Northern red- legged frogs (Rana aurora aurora) subject to increasing road mortality by evaluating the effectiveness of two commonly employed mitigation strategies, road-side fencing and wildlife underpasses. I find that the combination of two mitigation structures effectively reverse current population declines for R. aurora, but when I account for increasing vehicle traffic in the future, predict that additional mitigation will be required to prevent population declines and local extinction. In this thesis, I use physiological and demographic models to improve our understanding of the magnitude of current anthropogenic stressors to wild amphibian populations, but also highlight that modern stressors are frequently non-stationary, and present unique challenges to population-scale predictions.