Nicola J. Nelson | Geology Reports

USGS2022

Diverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity

Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.

Science↗

USGS2021

Conservation status of the world’s skinks (Scincidae): Taxonomic and geographic patterns in extinction risk

Our knowledge of the conservation status of reptiles, the most diverse group of terrestrial vertebrates, has improved dramatically over the past decade, but still lags behind that of the other tetrapod groups. Here, we conduct the first comprehensive assessment (~92% of the world’s ~1,714 described species) of the conservation status of skinks (Scincidae), the most speciose reptile family worldwide. Using IUCN criteria, we found that ~20% of species are threatened with extinction, and nine species are Extinct or Extinct in the Wild. The highest levels of threat are evident in Madagascar, and the Neotropics, and in the subfamilies Mabuyinae, Eugongylinae and Scincinae. The vast majority of threatened skink species were listed based primarily on their small geographic ranges (Criterion B, 83%; Criterion D2, 13%). Although the population trend of 42% of species were stable, 14% were found to have declining populations. The key threats to skinks are habitat loss due to agriculture, invasive species, and biological resource use. Distributions of 61% of species did not overlap with protected areas. Despite our improved knowledge of the conservation status of the world’s skinks, 8% of species remain to be assessed and 221 species (14%) are listed as Data Deficient. The conservation status of almost a quarter of the world’s skink species thus remains unknown. We use our updated knowledge of the conservation status of the group to develop and outline the priorities for the conservation assessment and management of the world’s skink species.

Biological Conservation↗