The evolution of begging display may be influenced by gene–environment interaction, through the mechanisms that adjust begging behaviour to environmental conditions of offspring, including intensity of sibling competition within broods. We decomposed the complex begging display of yellow-legged gull, Larus michahellis, chicks into two different functional components: begging for food (pecks) and drawing the attention of parents (chatter calls). We examined these begging components in 2-day-old chicks that hatched and grew up in foster nests, by performing a begging test for each chick alone without the hindrance of its foster siblings. Male chicks and those with poorer body condition begged for food at higher rates than females and those with better body condition, respectively. Chicks from larger broods begged for food more frequently, but chicks from male-biased broods begged less frequently. If begging is costly, chicks may adjust their begging efforts to the intensity of sibling competition. Frequency of chatter calls varied with sex, chick order within broods and body condition: females, the third chicks and those with poorer condition produced chatter calls more frequently. Genetic origin had a significant effect on frequency of chatter calls but not on begging for food, while foster nest effect was null in both traits. Therefore, chatter calls (but not pecks) can be subject to evolution under directional selection. Different begging components may have evolved through different evolutionary pathways.
Kim, S.Y., Noguera, J.C., Morales, J. & Velando, A., 2011. Quantitative genetic evidence for trade-off between growth and resistance to oxidative stress in a wild bird. Evolutionary ecology, 25(2), pp.461-472.
Why do animals not grow at their maximal rates? It has been recently proposed that fast growth leads to the accumulation of cellular damages due to oxidative stress, influencing subsequent performances and life span. Therefore, the trade-off between fast growth and oxidative stress may potentially function as an important constraint in the evolution of growth trajectories. We test this by examining a potential antagonistic pleiotropy between growth and blood resistance to controlled free radical attack in a wild bird using a cross-fostering design and robust quantitative genetic analyses. In the yellow-legged gull Larus michahellis decreased resistance to oxidative stress at age 8 days was associated with faster growth in mass, across the first 8 days of life, suggesting a trade-off between mass growth and oxidative-stress-related somatic maintenance. We found a negative genetic correlation between chick growth and resistance to oxidative stress, supporting the presence of the genetic trade-off between the two traits. Therefore, investment of somatic resources in growth could be constrained by resistance to oxidative stress in phenotypic and genetic levels. Our results provide first evidence for a potential genetic trade-off between life-history and underlying physiological traits in a wild vertebrate. Future studies should explore genetic trade-offs between life-history traits and other oxidative-stress-related traits.
Kim, S.Y., Noguera, J.C., Morales, J. & Velando, A., 2010. Heritability of resistance to oxidative stress in early life. Journal of Evolutionary Biology, 23(4), pp.769-775.
Oxidative stress has recently been suggested to play an important role in life-history evolution, but little is known about natural variation and heritability of this physiological trait. Here, we explore phenotypic variation in resistance to oxidative stress of cross-fostered yellow-legged gull (Larus cachinnans) chicks. Resistance to oxidative stress was not related to plasma antioxidants at hatching, which are mostly derived from maternal investment into eggs. Common environmental effects on phenotypic variation in resistance to oxidative stress were not significant. Heritability was relatively low and nonsignificant in hatchlings, but interestingly, the chicks of age 8 days showed high and significant heritability (h2 = 0.59). Our results suggest that resistance to oxidative stress is determined mainly by the genotype as chicks grow. Further work is required to explore the genetic role of oxidative stress in life-history evolution.