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Papers & Reports Effects of experimental warming and nutrient enrichment on wetland communities at the Arctic’s edge
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Authors: Davenport JM, Fishback L, Hossack BR | Date: 2020-09 | Outlet: Hydrobiologia
The disproportionate effects of warming for high-latitude, freshwater ecosystems has been well documented, but in some areas, changes have been further impacted by human-subsidized increases of waterfowl. To gain insight into how predicted changes in temperature and nutrient inputs might affect ecosystem function, we conducted a mesocosm experiment in the Canadian Subarctic with three levels of simulated goose enrichment and warming to measure changes in size and survival of larval wood frogs and boreal chorus frogs and primary productivity (phytoplankton and periphyton biomass). Our results highlight that the consequences of these rapid changes are non-linear and even non-intuitive, with species-specific consumer and ecosystem responses that depend on the magnitude of temperature and nutrient changes as well as community composition.
Field research at Yosemite toad breeding site - Dana Meadows, Yosemite National Park
Field research at Yosemite toad breeding site - Dana Meadows, Yosemite National Park
Sadinski W
Papers & Reports Climate’s cascading effects on disease, predation, and hatching success in Anaxyrus canorus, the threatened Yosemite toad
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Authors: Sadinski W, Gallant A L, Cleaver J E | Date: 2020-09-01 | Outlet: Global Ecology and Conservation | Format: .PDF
The U.S. Fish and Wildlife Service listed Anaxyrus canorus, the Yosemite toad, as federally threatened in 2014 based upon reported population declines and vulnerability to global-change factors. A. canorus lives only in California’s central Sierra Nevada at medium to sub-alpine elevations. Lands throughout its range are protected from development, but climate and other global-change factors potentially can limit populations. A. canorus reproduces in ultra-shallow wetlands that typically hydrate seasonally via melting of the winter snowpack. Lesser snowpacks in drier years can render wetland water volumes and hydroperiods insufficient to allow for successful breeding and reproduction. Additionally, breeding and embryogenesis occur very soon after wetlands thaw when overnight temperatures can be below freezing. Diseases, such as chytridiomycosis, which recently decimated regional populations of ranid species, also might cause declines of A. canorus populations. However, reported studies focused on whether climate interacts with any pathogens to affect fitness in A. canorus have been scarce. We investigated effects of these factors on A. canorus near Tioga Pass from 1996 to 2001. We found breeding subpopulations were distributed widely but inconsistently among potentially suitable wetlands and frequently consisted of small numbers of adults. We occasionally observed small but not alarming numbers of dead adults at breeding sites. In contrast, embryo mortality often was notably high, with the majority of embryos dead in some egg masses while mortality among coincidental Pseudacris regilla (Pacific treefrog) embryos in deeper water was lower. After sampling and experimentation, we concluded that freezing killed A. canorus embryos, especially near the tops of egg masses, which enabled Saprolegnia diclina (a water mold [Oomycota]) to infect and then spread through egg masses and kill more embryos, often in conjunction with predatory flatworms (Turbellaria spp.). We also concluded exposure to ultraviolet-B radiation did not play a role. Based upon our assessments of daily minimum temperatures recorded around snow-off during years before and after our field study, the freezing potential we observed at field sites during embryogenesis might have been commonplace beyond the years of our field study. However, interactions among snow quantity, the timing of snow-off, and coincidental air temperatures that determine such freezing potential make projections of future conditions highly uncertain, despite overall warming trends. Our results describe important effects from ongoing threats to the fitness and abundance of A. canorus via reduced reproduction success and demonstrate how climate conditions can exacerbate effects from pathogens to threaten the persistence of amphibian populations.

E Muths
Papers & Reports Determinants and consequences of dispersal in vertebrates with complex life cycles: a review of pond-breeding amphibians
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Authors: Cayuela H, Valenzuela-Sanchez A, Teulier L, Martinez-Solano I, Lena JP, Merila J, Muths E, Shine R, Quay L, Denoel M, Clobert J, Schmidt BR | Date: 2020-02 | Outlet: The Quarterly Review of Biology | Format: .PDF
Dispersal is a central process in ecology and evolution. It strongly influences the dynamics of spatially structured populations and affects evolutionary processes by shaping patterns of gene flow. For these reasons, dispersal has received considerable attention from ecologists, evolutionary biologists, and conservationists. However, although it has been studied extensively in taxa such as birds and mammals, much less is known about dispersal in vertebrates with complex life cycles such as pond-breeding amphibians. Over the past two decades researchers have taken an ever-increasing interest in amphibian dispersal and initiated both fundamental and applied studies, using a broad range of experimental and observational approaches. This body of research reveals complex dispersal patterns, causations and syndromes, with dramatic consequences for the demography, genetic, and the conservation of amphibian populations. In this review, our goals are to (1) redefine and clarify the concept of amphibian dispersal, (2) review current knowledge about the effects of individual (i.e., condition-dependent dispersal) and environmental (i.e., context-dependent dispersal) factors during the three stages of dispersal (i.e., emigration, immigration, transience), (3) identify the demographic and genetic consequences of dispersal in spatially structured amphibian populations, and (4) propose new research avenues to extend our understanding of amphibian dispersal.
Photo of a [I]Batrachoseps major[/I] being screened for fungal disease at Los Angeles World Airways.
Photo of a Batrachoseps major being screened for fungal disease at Los Angeles World Airways.
Robert Fisher, U.S. Geological Survey
Papers & Reports Slender salamanders (genus Batrachoseps) reveal Southern California to be a center for the diversification, persistence, and introduction of salamander lineages
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Authors: Jockusch E L, Hansen R W, Fisher R N, Wake D B | Date: 2020-08-14 | Outlet: PeerJ 8:e9599 | Format: .PDF
Background. The southern California biodiversity hotspot has had a complex geological history, with both plate tectonic forces and sea level changes repeatedly reconfiguring the region, and likely driving both lineage splittings and extinctions. Here we investigate patterns of genetic divergence in two species of slender salamanders (Plethodontidae: Batrachoseps) in this region. The complex geological history in combination with several organismal traits led us to predict that these species harbor multiple ancient mitochondrial lineages endemic to southern California. These species belong to a clade characterized by fine-scale mitochondrial structure, which has been shown to track ancient splits. Both focal species, Batrachoseps major and B. nigriventris, are relatively widely distributed in southern California, and estimated to have persisted there across millions of years. Recently several extralimital populations of Batrachoseps were found in the San Joaquin Valley of California, a former desert area that has been extensively modified for agriculture. The origins of these populations are unknown, but based on morphology, they are hypothesized to result from human-mediated introductions of B. major.
Methods. We sequenced the mitochondrial gene cytochrome b from a geographically comprehensive sampling of the mitochondrial lineages of B. major and B. nigriventris that are endemic to southern California. We used phylogenetic analyses to characterize phylogeographic structure and identify mitochondrial contact zones. We also included the San Joaquin Valley samples to test whether they resulted from introductions. We used a bootstrap resampling approach to compare the strength of isolation-by-distance in both Batrachoseps species and four other salamander species with which they co-occur in southern California.
Results. The northern lineage of B. major harbors at least eight deeply differentiated, geographically cohesive mitochondrial subclades. We identify geographic contact between many of these mtDNA lineages and some biogeographic features that are concordant with lineage boundaries. Batrachoseps nigriventris also has multiple deeply differentiated clades within the region. Comparative analyses highlight the smaller spatial scales over which mitochondrial divergence accumulates in Batrachoseps relative to most other salamander species in southern California. The extralimital populations of Batrachoseps from the San Joaquin Valley are assigned to B. major based on their mitochondrial haplotypes and are shown to result from at least two independent introductions from different source populations. We also suggest that B. major on Catalina Island, where it is considered native, may be the result of an introduction. Some of the same traits that facilitate the build-up of deep phylogeographic structure in Batrachoseps likely also contribute to its propensity for introductions, and we anticipate that additional introduced populations will be discovered.
Wolf spider feeding on a Blanchard's Cricket Frog
Wolf spider feeding on a Blanchard's Cricket Frog
Brad M. Glorioso
Papers & Reports ACRIS BLANCHARDI (Blanchard's Cricket Frog). Predation.
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Authors: Maldonado BR, Glorioso BM, Kidder RP | Date: 2020-06 | Outlet: Herpetological Review 51(2):296 | Format: .PDF
A natural history note describing predation of a Blanchard's Cricket Frog by a wolf spider at an elevated height.
Southern California slender salamander ([I]Batrachoseps major[/I]).
Southern California slender salamander (Batrachoseps major).
Chris Brown, U.S. Geological Survey
Papers & Reports Changes in capture rates and body size among vertebrate species occupying an insular urban habitat reserve
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Authors: Stanley TR, Clark RW, Fisher RN, Rochester CJ, Root SA, Lombardo KJ, Ostermann-Kelm SD | Date: 2020-06-29 | Outlet: Conservation Science and Practice 2020;e245. | Format: .PDF
Long-term ecological monitoring provides valuable and objective scientific information to inform management and decision making. In this paper we analyze 22 years of herpetofauna monitoring data from the Point Loma Ecological Conservation Area (PLECA), an insular urban reserve near San Diego, California. Our analysis showed that counts of individuals for one of the four most common terrestrial vertebrates declined, whereas counts for other common species increased or remained stable. Two species exhibited declines in adult body length, whereas biomass pooled over the five most common species increased over time and was associated with higher wet season precipitation. Although the habitat and vegetation at PLECA have remained protected and intact, we suspect that changes in arthropod communities may be driving changes in the abundance, growth, and development of insectivorous lizards. This study underscores the value of long-term monitoring for establishing quantitative baselines to assess biological changes that would otherwise go undetected.
An ornate chorus frog ([I]Pseudacris ornata[/I]) with brown coloration
An ornate chorus frog (Pseudacris ornata) with brown coloration
Peter Paplanus
Papers & Reports Pseudacris ornata
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Author: Glorioso BM | Date: 2010 | Outlet: Catalogue of American Amphibians and Reptiles | Format: .PDF
An in-depth species account of the ornate chorus frog (Pseudacris ornata).
A Big Mouth Cave Salamander ([I]Gyrinophilus palleucus necturoides[/I]) from Grundy County, Tennessee
A Big Mouth Cave Salamander (Gyrinophilus palleucus necturoides) from Grundy County, Tennessee
Brad M. Glorioso
Papers & Reports Growth, survival, longevity, and population size of the Big Mouth Cave Salamander (Gyrinophilus palleucus necturoides) from the type locality in Grundy County, Tennessee, USA
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Authors: Niemiller ML, Glorioso BM, Fenolio DB, Reynolds RG, Taylor SJ, Miller BT | Date: 2016 | Outlet: Copeia 104(1):35-41 | Format: .PDF
Salamander species that live entirely in subterranean habitats have evolved adaptations that allow them to cope with perpetual darkness and limited energy resources. We conducted a 26-month mark–recapture study to better understand the individual growth and demography of a population of the Big Mouth Cave Salamander (Gyrinophilus palleucus necturoides). We employed a growth model to estimate growth rates, age at sexual maturity, and longevity, and an open population model to estimate population size, density, detectability, and survival rates. Furthermore, we examined cover use and evidence of potential predation. Individuals probably reach sexual maturity in 3–5 years and live at least nine years. Survival rates were generally high (>75%) but declined during the study. More than 30% of captured salamanders had regenerating tails or tail damage, which presumably represent predation attempts by conspecifics or crayfishes. Most salamanders (>90%) were found under cover (e.g., rocks, trash, decaying plant material). Based on 11 surveys during the study, population size estimates ranged from 21 to 104 individuals in the ca. 710 m² study area. Previous surveys indicated that this population experienced a significant decline from the early 1970s through the 1990s, perhaps related to silvicultural and agricultural practices. However, our data suggest that this population has either recovered or stabilized during the past 20 years. Differences in relative abundance between early surveys and our survey could be associated with differences in survey methods or sampling conditions rather than an increase in population size. Regardless, our study demonstrates that this population is larger than previously thought and is in no immediate risk of extirpation, though it does appear to exhibit higher rates of predation than expected for a species believed to be an apex predator of subterranean food webs.
A three-toed amphiuma ([I]Amphiuma tridactylum[/I]) on a white background
A three-toed amphiuma (Amphiuma tridactylum) on a white background
Brad M. Glorioso
Papers & Reports Feeding times of Amphiuma tridactylum at Reelfoot Lake, Tennessee
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Authors: Glorioso BM, Niemiller ML, Cobb VA | Date: 2010 | Outlet: Journal of the Tennessee Academy of Science 85(3-4):87-90 | Format: .PDF
Feeding activity times were determined for Amphiuma tridactylum in a roadside slough adjacent to Reelfoot Lake in northwestern Tennessee. Twenty-nine A. tridactylum were captured using baited deep-water crawfish nets, with more than half of the captures being large adults. Despite the majority (82.4%) of trapping effort being concentrated in daytime hours, 82.7% of A. tridactylum captures were at night. Capture rates during nighttime hours were more than 25 times greater than during daytime capture rates. Though nocturnal, the mid-day captures indicated that A. tridactylum may exit their burrows during the day. This study also provides an alternative trapping method for Amphiuma, in which feeding times can be accurately determined.
A Spotted Salamander ([I]Ambystoma maculatum[/I]) egg mass from Kisatchie National Forest, Natchitoches Parish, Louisiana, with a passive integrated transponder (PIT) tag laid with embryos in the outer jelly (top middle).
A Spotted Salamander (Ambystoma maculatum) egg mass from Kisatchie National Forest, Natchitoches Parish, Louisiana, with a passive integrated transponder (PIT) tag laid with embryos in the outer jelly (top middle).
Brad M. Glorioso
Papers & Reports AMBYSTOMA MACULATUM (Spotted Salamander). REPRODUCTION.
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Authors: Glorioso BM, Waddle JH, Hefner J | Date: 2012 | Outlet: Herpetological Review 43(4):627-628 | Format: .PDF
This is a note on reproduction in Spotted Salamanders (Ambystoma maculatum) describing clutch sizes and several instances of inadvertant passive integrated transponder tag loss by tagged females via oviposition.