Repeatability but not heritability of metabolic rate in the alpine newt
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| Year of publication | 2019 |
| Type | Conference abstract |
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| Description | Standard metabolic rate (SMR) represents the minimum amount of energy required to maintain life functions of an ectotherm at a given body temperature. It belongs among basic life history traits affecting the allocation of acquired energy into growth, survival, and reproduction. Its adaptive evolution assumes lifetime repeatability and heritability. Studies examining both assumptions are rare and virtually missing in amphibian physiology. We examined seasonal and long-term repeatability, as well as two heritability estimates, using fullsib comparison and parent-offspring regression, of SMR in the 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, and accordingly no narrow sense heritability of SMR. This suggests that the sibling similarity and long-term repeatability of this trait is caused by phenotypic 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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