Tag Archives: demography

Journal Article, Publications

New paper published in Copeia on life history and demography of the Big Mouth Cave Salamander

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A paper on the life history and demography of a population of the Big Mouth Cave Salamander (Gyrinophilus palleucus necturoides) was recently published in the journal Copeia. The full citation and abstract are below.

Niemiller ML, Glorioso BM, Fenolio DB, Reynolds RG, Taylor SJ, & Miller BT. 2016. Growth, survival, longevity, and population size of the Big Mouth Cave Salamander (Gyrinophilus palleucus necturoides) from the type locality in Grundy County, Tennessee, USA. Copeia 104: 35-41.

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.

Publications

New paper on slimy salamander life history and demography published

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A paper comparing the life history and ecology of cave and surface populations of the Western Slimy Salamander (Plethodon albagula) in Texas was recently published in the journal Herpetological Conservation and Biology. The full citation and abstract are below.

Taylor SJ, Krejca JK, Niemiller ML, Dreslik MJ, & Phillips CA. Life history and demographic differences between cave and surface populations of the western slimy salamander, Plethodon albagula (Caudata: Plethodontidae), in central Texas. Herpetological Conservation and Biology 10: 740–752.

The Western Slimy Salamander (Plethodon albagula) in central Texas is known from both surface and cave environments. Threshold species, such as P. albagula, may be excellent candidates to study potential differences in life history traits during the evolutionary transition from surface into subterranean habitats. We conducted a 29-mo mark-recapture study of a surface and a cave population in Bell County, Texas, USA, to determine whether these populations differed in body size, growth rate, age at sexual maturity, and life span. We employed a growth model to estimate growth rate, age at sexual maturity, and life span, and an open population model to estimate population size, density, catchability, and survival rates. Salamanders were smaller on average and reached a smaller maximum size in the surface population compared to the cave population, which was skewed toward larger, older individuals. Growth trajectories were similar between populations, but the cave population reached sexual maturity faster (0.9–1.4 y) than the surface population (1.5–2.2 y). Survival rates were similar between populations. Although population size estimates were 10 times higher for the surface compared to the cave population, densities were similar between sites suggesting that habitat availability alone could explain population size differences. Plethodon albagula exhibits plasticity in growth, body size, and development, which may be adaptive and a function of extreme variation in surface environmental conditions. Subterranean habitats may be important for the long-term persistence of local populations, which may persist for years in subterranean habitats.