Special Issue "Amphibian Conservation"
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A special issue of Diversity (ISSN 1424-2818).
Deadline for manuscript submissions: closed (30 October 2009)
Special Issue Editor
Guest Editor
Dr. Ariadne Angulo
P.O. Box 19004, 360 A Bloor St. W., Toronto, ON, M5S 1X1, Canada
E-Mail: ariadne.angulo@utoronto.ca
Phone: +1 416 532 6071
Interests: amphibians; bioacoustics; biodiversity; conservation biology; evolutionary biology; systematics and taxonomy
Special Issue Information
Dear Colleagues,
During the First World Congress of Herpetology in Canterbury, in 1989, researchers began to suspect that amphibian population declines could be a global phenomenon. At the time, these suspicions were fuelled mostly by anecdotal information of researchers going back to their study sites and finding that populations of their study subjects were much reduced or completely gone. Twenty years later, and in light of much research, it is now widely accepted that amphibian declines are indeed an alarming global phenomenon; so much so that more amphibian species are considered to be at a greater risk of extinction than other major vertebrate groups. Threat factors are varied, with the most obvious and ubiquitous being habitat loss and pollution. However, there are other, less understood factors and their synergies, such as climate change and disease. But it is now thought that declines are escalating into extinctions, so it is urgent to take stock of what is already known, what still needs to be determined, and how to better address amphibian loss and implement amphibian conservation action. In this light, it seems timely to dedicate a commemorative special issue to the subjects of amphibian declines and amphibian conservation in 2009.
Dr. Ariadne Angulo
Guest Editor
Submission
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Diversity is an international peer-reviewed Open Access quarterly journal published by MDPI.
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Keywords
- amphibian declines
- amphibian extinctions
- assessments
- conservation
Published Papers (9 papers)
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Received: 30 July 2009 / Accepted: 7 September 2009 / Published: 11 September 2009
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Abstract: Species are being lost at increasing rates due to anthropogenic effects, leading to the recognition that we are witnessing the onset of a sixth mass extinction. Emerging infectious disease has been shown to increase species loss and any attempts to reduce extinction rates need to squarely confront this challenge. Here, we develop a procedure for identifying amphibian species that are most at risk from the effects of chytridiomycosis by combining spatial analyses of key host life-history variables with the pathogen's predicted distribution. We apply our rule set to the known global diversity of amphibians in order to prioritize pecies that are most at risk of loss from disease emergence. This risk assessment shows where limited conservation funds are best deployed in order to prevent further loss of species by enabling ex situ amphibian salvage operations and focusing any potential disease mitigation projects.
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Received: 12 August 2009 / Accepted: 21 September 2009 / Published: 24 September 2009
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Abstract: Although amphibians have experienced major global declines and an increasing extinction rate, recent results indicate that they are not as uniquely disadvantaged as previously supposed. Acquisition of robust data is evidently crucial to the determination of both absolute and relative rates of biodiversity declines, and thus in prioritising conservation actions. In Britain there is arguably a longer history of recording, and attempting to conserve, a wide range of species groups than anywhere else in the world. This stems from the early activities of Victorian naturalists in the nineteenth century, the establishment of natural history societies and, since the mid-twentieth century, a range of national recording schemes and organisations actively involved in conservation. In this review we summarise comparative evidence for British amphibians and reptiles concerning historical abundance, population trends and their causes, and outline how they relate to the situation elsewhere in Europe (and possibly the World). We discuss possible reasons why the plight of ectothermic vertebrates (fish, amphibians and reptiles) seems generally worse than that of endotherms (birds and mammals), as well as research priorities and factors likely to impact amphibians and reptile conservation in future.
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Received: 27 September 2009 / Accepted: 11 November 2009 / Published: 13 November 2009
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Abstract: Although amphibians have been widely promoted as indicators of biodiversity and environmental change, rigorous tests are lacking. Here key indicator criteria are distilled from published papers, and a species that has been promoted as a bioindicator, the great crested newt, is tested against them. Although a link was established between the presence of great crested newts and aquatic plant diversity, this was not repeated with the diversity of macroinvertebrates. Equally, amphibians do not meet many of the published criteria of bioindicators. Our research suggests that a suite of indicators, rather than a single species, will usually be required.
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Received: 27 October 2009 / Accepted: 13 November 2009 / Published: 17 November 2009
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Abstract: Coal extraction has been occurring in the Midwestern United States for over a century. Despite the pre-mining history of the landscape as woodlands, spent surface coalfields are often reclaimed to grasslands. We assessed amphibian and reptile species on a large tract of coal spoil prairie and found 13 species of amphibians (nine frog and four salamander species) and 19 species of reptiles (one lizard, five turtle, and 13 snake species). Two state-endangered and three state species of special concern were documented. The amphibian diversity at our study site was comparable to the diversity found at a large restored prairie situated 175 km north, within the historic prairie peninsula.
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Received: 9 November 2009 / Accepted: 7 December 2009 / Published: 11 December 2009
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Abstract: Amphibian declines have been reported in mountainous areas around the western USA. Few data quantify the extent of population losses in the Pacific Northwest, a region in which amphibian declines have received much attention. From 2001–2004, we resurveyed historical breeding sites of two species of conservation concern, the Western Toad (Bufo [=Anaxyrus] boreas) and Cascades Frog (Rana cascadae). We detected B. boreas breeding at 75.9% and R. cascadae breeding at 66.6% of historical sites. When we analyzed the data using occupancy models that accounted for detection probability, we estimated the current use of historically occupied sites in our study area was 84.9% (SE = 4.9) for B. boreas and 72.4% (SE = 6.6) for R. cascadae. Our ability to detect B. boreas at sites where they were present was lower in the first year of surveys (a low snowpack year) and higher at sites with introduced fish. Our ability to detect R. cascadae was lower at sites with fish. The probability that B. boreas still uses a historical site for breeding was related to the easting of the site (+) and the age of record (-). None of the variables we analyzed was strongly related to R. cascadae occupancy. Both species had increased odds of occupancy with higher latitude, but model support for this variable was modest. Our analysis suggests that while local losses are possible, these two amphibians have not experienced recent, broad population losses in the Oregon Cascades. Historical site revisitation studies such as ours cannot distinguish between population losses and site switching, and do not account for colonization of new habitats, so our analysis may overestimate declines in occupancy within our study area.
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Received: 4 November 2009 / Accepted: 19 December 2009 / Published: 31 December 2009
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Abstract: We have studied the population genetic structure of slightly admixed populations of crested newts (Triturus cristatus and T. carnifex) in a continuously fragmented landscape, located in northern Salzburg (Austria) and neighbouring Bavaria (Germany). Crested newts are listed as Critically Endangered in the provincial Red List of Salzburg and strictly protected by the EU Habitats Directive. We used seven polymorphic microsatellite loci to evaluate genetic diversity and processes that may determine the genetic architecture of populations. Genetic diversity was moderate, pairwise FST-values were comparatively high showing significant genetic differentiation and limited gene flow. Isolation by distance was significant for the whole data set, but not significant when calculated for T. cristatus- and T. carnifex-like populations separately. Bayesian analyses of population structure, using three different programs showed similar results. Spatial statistics reveal that the geographical isolation of populations is very high.
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Received: 4 November 2009 / Accepted: 26 December 2009 / Published: 5 January 2010
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Abstract: It is well established that a decrease in genetic variation can lead to reduced fitness and lack of adaptability to a changing environment. Amphibians are declining on a global scale, and we present a four-point argument as to why this taxonomic group seems especially prone to such genetic processes. We elaborate on the extent of recent fragmentation of amphibian gene pools and we propose the term dissociated populations to describe the residual population structure. To put their well-documented loss of genetic diversity into context, we provide an overview of 34 studies (covering 17 amphibian species) that address a link between genetic variation and >20 different fitness traits in amphibians. Although not all results are unequivocal, clear genetic-fitness-correlations (GFCs) are documented in the majority of the published investigations. In light of the threats faced by amphibians, it is of particular concern that the negative effects of various pollutants, pathogens and increased UV-B radiation are magnified in individuals with little genetic variability. Indeed, ongoing loss of genetic variation might be an important underlying factor in global amphibian declines.
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Received: 30 October 2009 / Accepted: 18 January 2010 / Published: 27 January 2010
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Abstract: Rapid, global declines among amphibians are partly alarming because many occur for apparently unknown or enigmatic reasons. Moreover, the relationship between phylogeny and enigmatic declines in higher clades of the amphibian phylogeny appears at first to be an intractable problem. I present a working solution by assessing threatening processes potentially underlying enigmatic declines in the family, Hylidae. Applying comparative methods that account for various evolutionary scenarios, I find extreme concentrations of threatening processes, including pollution and habitat loss, in the clade Hylini, potentially influenced by traits under selection. The analysis highlights hotspots of declines under phylogenetic influence in the genera Isthmohyla, Plectrohyla and Ptychohyla, and geographically in Mexico and Guatemala. The conservation implications of concentrated phylogenetic influence across multiple threatening processes are twofold: Data Deficient species of threatened clades should be prioritized in future surveys and, perhaps, a greater vulnerability should be assigned to such clades for further consideration of clade-level conservation priorities.
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Received: 10 November 2009 / Accepted: 20 February 2010 / Published: 25 February 2010
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Abstract: As part of an overall decline in biodiversity, populations of many organisms are declining and species are being lost at unprecedented rates around the world. This includes many populations and species of amphibians. Although numerous factors are affecting amphibian populations, we show potential direct and indirect effects of climate change on amphibians at the individual, population and community level. Shifts in amphibian ranges are predicted. Changes in climate may affect survival, growth, reproduction and dispersal capabilities. Moreover, climate change can alter amphibian habitats including vegetation, soil, and hydrology. Climate change can influence food availability, predator-prey relationships and competitive interactions which can alter community structure. Climate change can also alter pathogen-host dynamics and greatly influence how diseases are manifested. Changes in climate can interact with other stressors such as UV-B radiation and contaminants. The interactions among all these factors are complex and are probably driving some amphibian population declines and extinctions.
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Last update: 17 February 2011
