The contributions of individual traits to survival among terrestrial juvenile pond-breeding salamanders

Individual survival is influenced by interactions between local environmental conditions and an organism’s morphological, behavioral, and physiological traits. Studies examining the effects of individual phenotypes on survival under variable conditions are relatively rare among early transitional life stages, though the vital rates of these life stages can importantly influence population dynamics. We experimentally examined the effects of initial body mass, movement, standard metabolic rate (SMR), and respiratory surface area water loss (RSAWL) on survival in the transitional juvenile life stage of two biphasic amphibian species (Ambystoma maculatum and A. opacum) in a seven-month mark-recapture study under semi-natural conditions. Juveniles with a larger initial body mass, lower initial SMR, and/or a lower tendency to change locations had a higher likelihood of known survival. In contrast, we found no significant effect of RSAWL on juvenile survival. The relationships between individual phenotypes and survival did not differ between species, but equivalent species-specific survival rates may have been attributed to larger initial body sizes in A. maculatum and lower SMR in A. opacum. Our results illuminate the complex ways in which individual traits influence survival during the early transitional life stage of two ambystomatid species under varying abiotic conditions. More generally, our findings illustrate potential advantages of simultaneously examining multiple traits to evaluate survival.

Methods
Please see the associated manuscript for full methodological details.