We currently work on three main research lines:
Signals in social conflicts: plasticity of behavioural response rules
In animal societies, including humans, information exchange forms a central component of the interactions among group members. Learning how individuals use social information to adjust their decision rules is one of the key questions in evolutionary biology, such as the origin of sociality and cooperation. A key social factor that facilitates information exchange is the expression of signals. For instance, badges of status inform rivals about the probability of winning a contest and can reduce the costs of competitive interactions.
We use animal family life as a model social environment to explore how the expression of signals shapes individual decision rules and the resolution of conflicts. For example, at the intra-specific level, in gulls, we have found that parental decision rules can shift from flexible to fixed according to signals expressed by other family members (Morales et al. 2009 Proceedings B; pdf download). In the blue tit (Cyanistes caeruleus), we have observed that a signal (plumage colouration) expressed by the offspring modulates costly interactions with multiple family members (Morales & Velando 2018 Behav Ecol; pdf download). Also, across bird species, the presence of conspicuous feathers in the offspring is more common in lineages with larger families, that is, in those with a higher potential for intra-family conflict (Morales et al. 2019 Behav Ecol).
Maternal effects and plastic responses to the environment
The expression of social signals can be modulated by so-called parental effects: aspects of the parents’ phenotype that are partly independent of genetic effects. For example, prenatal nourishment via eggs affects begging signals and the development of coloured traits in the offspring. It has been suggested that maternal effects acting before birth enable the offspring to adapt to a variable post-hatching world. Thus, we are now investigating whether early maternal effects such as hormone and carotenoid transference via eggs adaptively “program” offspring social traits.
The role of signals in sexual selection and beyond
The evolution of female ornamentation is among our favourite themes. We have experimentally demonstrated the long-standing idea that fecundity costs constrain the degree of ornamentation in females and explains sexual dimorphism (Morales, Velando & Torres Behav Ecol 2009; pdf download).
Moreover, females can express ornaments that are unique to their sex. This is the case of egg colouration, which has been proposed to function as a signal of female quality to induce male investment in parental care. We have studied this interesting aspect of sexual selection in avian species with different life histories like seabirds and songbirds.
At present, we are interested in whether signals expressed both by male and female parents play a role beyond sexual selection, for example, in parent-offspring interactions. This has been little studied in different taxa (Morales & Velando 2013 Anim Behav; pdf download) and we are now exploring this question at the intra-specific level, in blue tit families.