Learn More
It is poorly understood whether female morphological and behavioural traits can be used as 'signals'. In particular, experimental tests of the hypothesis that female ornaments reflect quality are scarce. Here, we experimentally examine whether female plumage coloration might signal maternal quality in the blue tit, Cyanistes caeruleus by forcing half of the(More)
In many species mature individuals delay independent reproduction and may help others to reproduce. This behaviour is often explained through ecological constraints, although recently attention has also been paid to the variation in habitat quality. If the quality of vacant habitat influences the fitness trade-off between delaying reproduction and breeding(More)
Many vertebrates use colour vision for vital behaviour but their visual performance in dim light is largely unknown. The light intensity threshold of colour vision is known only for humans, horses and two parrot species. Here, we first explore this threshold in a passerine bird, the blue tit (Cyanistes caeruleus). Using classic conditioning of colour cues(More)
1. A growing number of studies suggest that female ornaments are linked to maternal quality and influence male mate choice. These findings challenge the traditional male-biased view of sexual selection and the hypothesis that female ornaments are the outcome of a genetic correlation with male ornaments. To further test the hypothesis that female traits have(More)
Unexpected sex ratio adjustment in a colonial cooperative bird: pairs with helpers produce more of the helping sex whereas pairs without helpers do not Abstract For cooperatively breeding species, the most popular and intensely debated explanation for sex ratio variation is the helper repayment hypothesis. It predicts overall sex ratio bias towards the(More)
While the study of the origins of biological diversity across species has provided numerous examples of adaptive divergence, the realization that it can occur at microgeographic scales despite gene flow is recent, and scarcely illustrated. We review here evidence suggesting that the striking phenotypic differentiation in ecologically relevant traits(More)
In animal societies, individuals face the dilemma of whether to cooperate or to compete over a shared resource. Two intertwined mechanisms may help to resolve this enduring evolutionary dilemma by preventing conflicts and thereby mediating the costs of living in groups: the establishment of dominance hierarchies and the use of ‘badge-of-status’ for(More)
Sexual dimorphism is widely used as an indirect measure of the intensity of sexual selection. It is also a way to evaluate whether different selective pressures act on males and females. Dichromatism, defined as a difference in colouration between males and females, may for instance result from selection for crypsis in females and selection for(More)
Population trends are determined by gains through reproduction and immigration, and losses through mortality and emigration. These demographic quantities and resulting population dynamics are affected by different external and internal drivers. We examined how these demographic quantities were affected by weather, research-induced disturbance, local(More)
In egg laying species, breeding females may adjust the allocation of nutrients or other substances into eggs in order to maximise offspring or maternal fitness. Cooperatively breeding species offer a particularly interesting context in which to study maternal allocation because helpers create predictably improved conditions during offspring development.(More)