Evolutionary ecological perspectives on bird family life: A study into the genetic and phenotypic mechanisms of offspring begging.

Begging, the solicitation of food from parents by as yet dependent offspring, forms a trait with direct and significant consequences on growth, survival, and thus ultimately on fitness. Obviously, begging for food from parents should elicit the transfer of resources, typically a greater amount than parents are selected to provide, since parents and offspring are, at least in birds, not genetically identical. When offspring seeks parental investment, their begging exerts a selective pressure on parental provisioning. But begging is at the same time also target of selection, because it is influenced by the parental response. Both behaviors should, therefore, ultimately become co-adapted. Being agent and target of selection, begging follows a complex evolutionary trajectory, which is additionally flavoured by the evolutionary conflict over parental investment.From this it becomes clear that it requires detailed information on both selection and inheritance of begging in order to understand its evolutionary potential. A very powerful quantitative genetic tool to study genetic mechanisms and evolutionary processes is to impose artificial selection upon the trait of interest, here begging. Artificial selection not only allows to identify the pattern of inheritance, but also to investigate genetic covariances and correlated responses in traits that generate trade-offs or that are co-adapted. This opens the possibility to test important evolutionary ecological predictions for instance in the context of evolutionary conflicts of interest and the honest signaling of offspring need. The use of artificial selection is also suitable to identify underlying control mechanisms via a correlated selection on physiological traits. Physiological mechanisms have the potential to affect or even constrain the response to selection by linking the expression of different traits and by generating trade-offs across contexts or life-history stages. Studying the phenotypic mechanisms such as the regulating role of testosterone is, therefore, necessary and will complement the research into the genetic mechanisms. Ultimately, the combined information will help to understand what mechanisms make begging adaptive and thus improve our understanding of the evolutionary ecology of life-history traits and fitness components.

Keywords:EXPERIMENTAL STUDY, GENOTYPE-PHENOTYPE CORRELATION, NATURAL SELECTION

Disciplines:Animal biology, Endocrinology and metabolic diseases