Summary: Kim et al. (2011)

Gene-environment interactions influence the evolution of begging displays in bird chicks. The strength (intensity) of within-brood sibling competition, one mechanism thought to influence evolution of begging display, can cause begging behaviour to vary in response to environmental conditions experienced by offspring. Kim et al. (2011) broke down the the begging display of yellow-legged gull (Larus michahelis)chicks into 2 different functional components: 1) pecks (associated with pee calls) = begging for food; and 2) chatter calls = attention-seeking behaviour. They found, using a begging test, that males and chicks in poor-body condition begged at higher rates, while chicks from male-biased broods begged less frequently. Furthermore, chicks from larger broods begged more frequently. Their results suggest that chicks adjust their individual begging efforts to the strength of of sibling competition, if begging is costly. They also found that genetic origin had a significant effect on the frequency of chatter calls, but not on begging. Frequency of chatter calls also varied with sex, chick order within a brood and body condition. Kim et al. (2011) suggest that chatter calls can be subject to evolution under directional selection and that different begging components may have evolved through different evolutionary pathways.