patterns result from three categories of causes, of which competition is just one; the other two are predation and factors that operate independently of interspecific interactions, such as physiological constraints. Moreover, in each of the case histories presented below, we find two or more mechanisms interacting in complex ways. In no case does a single factor, for example competition, ever act alone. These case histories therefore provide an admonishment to single-minded tests of community-wide patterns that pit competition against everything (or nothing) else. Rather, a variety of factors may cause community-wide patterns such as resource partitioning, and the relative importance of these factors may differ among taxa and among communities at different geographic locations.

Resource Partitioning in Amphibians and Reptiles

Climate change could be a game-changer for biodiversity conservation, potentially invalidating many established methods including those employed in vulnerability assessments. Now, a simulation study finds that extinction risk due to climate change can be predicted using measurable spatial and demographic variables. Interestingly, most of those variables identified as important are already used in species conservation assessment. There is an urgent need to develop effective vulnerability assessments for evaluating the conservation status of species in a changing climate1. Several new assessment approaches have been proposed for evaluating the vulnerability of species to climate change2,3,4,5 based on the expectation that established assessments such as the IUCN Red List6 need revising or superseding in light of the threat that climate change brings. However, although previous studies have identified ecological and life history attributes that characterize declining species or those listed as threatened7,8,9, no study so far has undertaken a quantitative analysis of the attributes that cause species to be at high risk of extinction specifically due to climate change. We developed a simulation approach based on generic life history types to show here that extinction risk due to climate change can be predicted using a mixture of spatial and demographic variables that can be measured in the present day without the need for complex forecasting models. Most of the variables we found to be important for predicting extinction risk, including occupied area and population size, are already used in species conservation assessments, indicating that present systems may be better able to identify species vulnerable to climate change than previously thought. Therefore, although climate change brings many new conservation challenges, we find that it may not be fundamentally different from other threats in terms of assessing extinction risks.

/pdf/life-history-and-spatial-traits-predict-extinction-risk-due-5by8jz9hnr.pdf

Life history and spatial traits predict extinction risk due to climate change

Conserving biodiversity in the face of ever-increasing human pressure is hampered by our lack of basic information on species occurrence, distribution, abundance, habitat requirements, and threats. Obtaining this information requires efficient and sensitive methods capable of detecting and quantifying true occurrence and diversity, including rare, cryptic and elusive species. Environmental DNA (eDNA) is an emerging technique that can increase our ability to detect and quantify biodiversity, by overcoming some of the challenges of labor-intensive traditional surveys. The application of eDNA in ecology and conservation has grown enormously in recent years, but without a concurrent growth in appreciation of its strengths and limitations. In many situations, eDNA may either not work, or it may work but not provide the information needed. Problems with (1) imperfect detection, (2) abundance quantification, (3) taxonomic assignment, (4) eDNA spatial and temporal dynamics, (5) data analysis and interpretation, and (6) assessing ecological status have all been significant. The technique has often been used without a careful evaluation of the technical challenges and complexities involved, and a determination made that eDNA is the appropriate method for the species or environment of interest. It is therefore important to evaluate the scope and relevance of eDNA-based studies, and to identify critical considerations that need to be taken into account before using the approach. We review and synthesize eDNA studies published to date to highlight the opportunities and limitations of utilizing eDNA in ecology and conservation. We identify potential ways of reducing limitations in eDNA analysis, and demonstrate how eDNA and traditional surveys can complement each other.

/pdf/applications-of-environmental-dna-edna-in-ecology-and-2arrn13fgm.pdf

Applications of environmental DNA (eDNA) in ecology and conservation: opportunities, challenges and prospects

: Installation and maintenance of stormwater ponds to detain and treat runoff from impervious surfaces is a common method of stormwater control in developed areas. That these ponds capture pollutants, however, is of concern for wildlife species that use the ponds, particularly pond-breeding amphibians. To assess the relative contribution of stormwater ponds to the persistence of amphibian populations in suburban landscapes, we compared amphibian use of stormwater ponds and other available wetlands in suburban and forested watersheds. We surveyed three suburban and three primarily forested first-order watersheds to identify all potential wetlands that might serve as breeding sites for pond-breeding amphibians. We performed call, egg-mass, and larval surveys to measure breeding effort at each wetland in spring and summer 2007 and 2008. In suburban watersheds most (89%) of the wetlands that had breeding activity were either stormwater ponds or otherwise artificial. This pattern was also evident in the forested watersheds, where amphibians were primarily found breeding in wetlands created by past human activity. Late-stage larvae were found only in anthropogenic wetlands in all study areas because the remaining natural wetlands did not hold water long enough for larvae to complete development. Our results suggest that in urban and suburban landscapes with naturally low densities of wetlands, wetlands created by current or historic land uses may be as important to amphibian conservation as natural wetlands or pools and that management strategies directed at urban and suburban landscapes should recognize and incorporate human-created wetlands.

Value of artificial habitats for amphibian reproduction in altered landscapes.

Context. 
Environmental DNA, or eDNA, methods are a novel application of non-invasive genetic sampling in which DNA from organisms is detected via sampling of water or soil, typically for the purposes of determining the presence or absence of an organism. eDNA methods have the potential to revolutionise the study of rare or endangered taxa.Aims. 
We evaluated the efficacy of eDNA sampling to detect populations of an amphibian of conservation concern, the eastern hellbender (Cryptobranchus a. alleganiensis), indirectly from their aquatic environments.Methods. 
We developed species-specific primers, validated their specificity and sensitivity, and assessed the utility of our methods in silico and in laboratory trials. In the field, we collected water samples from three sites with known densities of hellbenders, and from one site where hellbenders do not occur. We filtered water samples, extracted DNA from filters, and assayed the extraction products for hellbender DNA by using polymerase chain reaction (PCR) and gel electrophoresis.Key results. 
Our methods detected hellbenders at densities approaching the lowest of reported natural densities. The low-density site (0.16 hellbenders per 100 m2) yielded two positive amplifications, the medium-density site (0.38 hellbenders per 100 m2) yielded eight positive amplifications, and the high-density site (0.88 hellbenders per 100 m2) yielded 10 positive amplifications. The apparent relationship between density and detection was obfuscated when river discharge was considered. There was no amplification in any negative control.Conclusion. 
eDNA methods may represent a cost-effective means by which to establish broad-scale patterns of occupancy for hellbenders.Implications. 
eDNA can be considered a valuable tool for detecting many species that are otherwise difficult to study.

/pdf/an-edna-approach-to-detect-eastern-hellbenders-5g7ok63kln.pdf

An eDNA approach to detect eastern hellbenders (Cryptobranchus a. alleganiensis) using samples of water

Though locally abundant throughout the high mountains of West Virginia, intensive studies on the natural history and population structure of the hellbender, Cryptobranchus alleganiensis, have not been conducted in the state. From 1998–2000 we conducted a mark-recapture study within a 216 × 18 m stream section in east-central West Virginia using diurnal and nocturnal survey methods. Ninety-nine captures of 44 individuals were recorded. Density estimates ranged from 0.8–1.2 individuals/100 m2. The sex ratio was 1.2:1. Sexual dimorphism was apparent, as females were longer and heavier than males. However, the longest males were underweight compared to their predicted mass. This population was highly skewed toward large adults, and larvae and juveniles were not encountered. The mean inter-capture distance was 35.8 m and 95% MCP home range estimates averaged 198 m2. Water depth where hellbenders were captured ranged from 16–56 cm and individuals were never captured in heavily silted areas. Hellbender ...

Life History of the Hellbender, Cryptobranchus Alleganiensis, in a West Virginia Stream

Seasonal Changes in Nocturnal Activity of the Hellbender, Cryptobranchus alleganiensis, in West Virginia

Ecologists have long studied extrinsic factors to explain intraspecific variation in phenotypic expression, yet assessment of intrinsic factors may also be important in understanding intraspecific phenotypic variation. Resources are allocated among the competing life history traits of growth, reproduction and storage. Thus, assessment of the suite of these traits may be critical to better understand phenotypic expression of life history traits. We examined growth (body size), reproduction (reproductive frequency) and storage (tail fat) of museum specimens of Red-backed Salamanders, Plethodon cinereus, at low and high elevations to test how altitudinal differences affected resource allocation among these life history traits. Based on the findings from previous studies, we hypothesized that animals at high elevations would be smaller in body size, reproduce less frequently and have less fat storage. We found that adult animals at high elevations were smaller in body size, reproduced less frequently (only females), but had greater tail fat storage relative to their body size than their counterparts at low elevations. The stored fat on tails can be used when salamanders are short of food. It may be more crucial for animals at high elevations to store more fuel for survival because longer and colder winters prevent them from actively foraging for longer periods. Our results suggest that resource allocation to growth and reproduction may be more constrained at high elevations because of the shorter growing season and greater allocation of energy into storage.

https://bioone.org/journals/The-American-Midland-Naturalist/volume-163/issue-1/0003-0031-163.1.87/Resource-Allocation-and-Life-History-Traits-of-Plethodon-cinereus-at/10.1674/0003-0031-163.1.87.pdf

Resource Allocation and Life History Traits of Plethodon cinereus at Different Elevations

The original Picea rubens (Red Spruce) forest in West Virginia covered approximately 1.5 million acres, most of which was eliminated between 1870 and 1920 by clear-cutting and conflagrations. The total range of Plethodon nettingi (Cheat Mountain Salamander) was confined within this Red Spruce forest. Fires burned the duff and soil to the bedrock in many places, thus eliminating salamander habitats. It is hypothesized that Cheat Mountain Salamanders were eradicated throughout much of their range, and only areas with large emergent rocks or boulder fields provided refugia where they survived.

The Appalachian Inferno: Historical Causes for the Disjunct Distribution of Plethodon nettingi (Cheat Mountain Salamander)

https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13210

Thomas K. Pauley

Papers

Life History of the Hellbender, Cryptobranchus Alleganiensis, in a West Virginia Stream

Seasonal Changes in Nocturnal Activity of the Hellbender, Cryptobranchus alleganiensis, in West Virginia

Resource Allocation and Life History Traits of Plethodon cinereus at Different Elevations

The Appalachian Inferno: Historical Causes for the Disjunct Distribution of Plethodon nettingi (Cheat Mountain Salamander)

Using environmental DNA and occupancy modelling to identify drivers of eastern hellbender (Cryptobranchus alleganiensis alleganiensis) extirpation