| Popis: |
Changing environmental conditions cause changes in the distributions of phenotypic traits in natural populations. Adaptation to environmental conditions can occur via micro-evolution, and, likely more often, via phenotypic plasticity. Phenotypic plasticity, when heritable, itself also has the potential for a micro-evolutionary response to selection, facilitating a population’s ability to deal with short-term environmental change and, ultimately, its viability. In this study, we investigated individual and additive genetic variation in, and selection on, plasticity in three phenological traits: the timing of arrival from wintering grounds, the interval between arrival and initiation of breeding, and the timing of reproduction, in response to two environmental factors. We used 25 years of individual-level observations of phenology of a long-distance migratory seabird, the common tern (Sterna hirundo), together with information on sea surface temperature at the wintering grounds and food availability at the breeding grounds. We found evidence for individual variation in multidimensional plasticity of arrival and laying dates, and, to a lesser extent, for heritability of plasticity in arrival date. The intercepts of the three phenological traits were under strong directional selection towards being early, while plasticity of arrival in response to food availability was the only response under selection, favoring greater plasticity. Altogether, the low heritability of plasticity, coupled with weak selection pressures, suggest little evolutionary potential for multidimensional plasticity in spring phenology in this natural population. |
