Publication details

Repeatability and heritability of metabolic rate in a slow-living ectotherm



Year of publication 2020
Type Conference abstract
Description Standard metabolic rate (SMR) represents the minimum amount of energy required to maintain basic life functions of an ectotherm at a given body temperature. Its magnitude affects the allocation of acquired energy into growth, survival and reproduction; therefore, it is a key component of organismal life histories. Its adaptive evolution assumes similarity both within individual lifetime, or repeatability, and across generations, heritability. Studies examining both assumptions are rare and focused on taxa with short generation times. We examined repeatability, as well as heritability, of SMR in the slow-living ectotherm, alpine newt (Ichthyosaura alpestris). Using intermittent respirometry, we repeatedly measured SMR in both newt cohort for five years since metamorphosis, and its metamorphosed offspring. SMR was consistently repeatable across one season and the whole measurement period. Sibling juveniles had more similar SMR than unrelated offspring indicating broad-sense heritability in this trait. Offspring and mid-parent values showed no similarity suggesting the lack of additive genetic variation in SMR. This suggests that the sibling similarity and long-term repeatability of this trait is caused by developmental plasticity and (or) dominance genetic variation rather than by additive genetic variation. We conclude that SMR fulfills assumption for phenotypic selection but the evolutionary potential of SMR is rather limited in this species. Our results have important implications for understanding sources of individual variation and eco-evolutionary significance of SMR in newts and other slow-living ectotherms.
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