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.

Please see the associated manuscript for full methodological details.

Available files include:

• R scripts used to:
  • conduct Bayesian binomial generalized linear mixed models and construct Figures 1 and 2 (Resp_Survival_2017-2018_Sept2021.R)
  • examine changes in juvenile body sizes prior to release (Metamorph_2017_Release_BodySize_Apr2021.R) and over the course of the study period (Phys_Surv_Change_Size_Apr2021.R)
  • calculate the effect of relative apparent activity levels on juvenile survival to produce Figure 3 (Location_Known_Alive_Apr2021.R)
  • calculate traditional selection coefficients (Selection-Coefficients_Sept2021.R).
• All necessary data files to run these R scripts and support the findings of our study (WVP_RSAWL_2017-2018_Survival.csv, Released_Rounds3-5_RSAWL_MINVCO2_2017.csv, abiotic.csv, Metamorph_2017_Release_Data.csv, Phys_Surv_Change_Size.csv, Location_KnownAlive.csv).

Scripts were developed and run using R version 4.0.0.