Data from: Macroevolution of desiccation-related morphology in plethodontid salamanders as inferred from a novel surface area to volume ratio estimation approach

Evolutionary biologists have long been interested in the macroevolutionary
consequences of various selection pressures, yet physiological responses
to selection across deep time are not well understood. In this paper, we
investigate how a physiologically-relevant morphological trait, surface
area to volume ratio (SA:V) of lungless salamanders, has evolved across
broad regional and climatic variation. SA:V directly impacts an organisms’
ability to retain water, leading to the expectation that smaller SA:Vs
would be advantageous in arid, water-limited environments. To explore the
macroevolutionary patterns of SA:V, we first develop an accurate method
for estimating SA:V from linear measurements. Next, we investigate the
macroevolutionary patterns of SA:V across 257 salamander species,
revealing that higher SA:Vs phylogenetically correlate with warmer, wetter
climates. We also observe higher SA:V disparity and rate of evolution in
tropical species, mirrored by higher climatic disparity in available and
occupied tropical habitats. Taken together, these results suggest that the
tropics have provided a wider range of warmer, wetter climates for
salamanders to exploit, thereby relaxing desiccation pressures on SA:V.
Overall, this paper provides an accurate, efficient method for quantifying
salamander SA:V, allowing us to demonstrate the power of physiological
selection pressures in influencing the macroevolution of morphology.