It takes two to tango: consequences of artificial selection on offspring begging for parent-offspring communication (#521)
Solicitation for food (so-called begging) by as yet dependent nestlings of altricial bird species is thought to signal offspring need towards the parents. Begging is costly to perform but crucial for the nestling via its positive effects on growth and survival. However, offspring begging is subject to a complex evolutionary trajectory, because it is not only affected by the offspring’s state, but also by the way how parents alter their provisioning in response to it. Begging is therefore not only dependent on the genotype of the offspring (direct genetic effect) but also on its parents’ genotype (indirect genetic effect). Parental provisioning and offspring begging are consequently likely to coevolve, which may ultimately lead to a coadaptation between these traits. Such coadaptation has been shown at the phenotypic level, it is now important to understand if it results from a genetic correlation. One powerful tool to study this question is to impose artificial selection on either of the behavioural traits involved, and to study the consequences on parent-offspring communication.
Using canaries (Serinus canaria) as a model species we applied a bidirectional artificial selection on low and high begging behaviour for three consecutive generations. We measured the response to selection, potential consequences for offspring development, and the effects of our selection on traits that are supposed to be co-adapted, in particular parental provisioning. We found a positive response to artificial selection in the high begging line, while our selection appeared to be less successful in the low begging line. The latter may be due to the fact that begging presents a fitness-relevant trait, which is more difficult to negatively select on. Nestlings survived indeed significantly less well in the low begging line compared to the high begging line. We are currently analysing whether the observed changes in offspring begging affected parent-offspring communication. The outcome of these analyses will provide important insights for our understanding of coadaptation between parental provisioning and offspring begging.