Abstract
BackgroundThe coevolution of male traits and female mate preferences has led to the elaboration and diversification of sexually selected traits; however the mechanisms that mediate trait-preference coevolution are largely unknown. Carotenoid acquisition and accumulation are key determinants of the expression of male sexually selected carotenoid-based coloration and a primary mechanism maintaining the honest information content of these signals. Carotenoids also influence female health and reproduction in ways that may alter the costs and benefits of mate choice behaviours and thus provide a potential biochemical link between the expression of male traits and female preferences. To test this hypothesis, we manipulated the dietary carotenoid levels of captive female house finches (Carpodacus mexicanus) and assessed their mate choice behavior in response to color-manipulated male finches.ResultsFemales preferred to associate with red males, but carotenoid supplementation did not influence the direction or strength of this preference. Females receiving a low-carotenoid diet were less responsive to males in general, and discrimination among the colorful males was positively linked to female plasma carotenoid levels at the beginning of the study when the diet of all birds was carotenoid-limited.ConclusionsAlthough female preference for red males was not influenced by carotenoid intake, changes in mating responsiveness and discrimination linked to female carotenoid status may alter how this preference is translated into choice. The reddest males, with the most carotenoid rich plumage, tend to pair early in the breeding season. If carotenoid-related variations in female choice behaviour shift the timing of pairing, then they have the potential to promote assortative mating by carotenoid status and drive the evolution of carotenoid-based male plumage coloration.
Highlights
The coevolution of male traits and female mate preferences has led to the elaboration and diversification of sexually selected traits; the mechanisms that mediate trait-preference coevolution are largely unknown
These models predict that sexual selection and the assortative mating of attractive males and choosy females inevitably leads to a positive genetic covariance between male trait and female preference
Results of univariate ANCOVAs testing the effects of dietary carotenoid supplementation and pre-supplementation plasma carotenoid levels on the three components of female choice for male plumage coloration
Summary
The coevolution of male traits and female mate preferences has led to the elaboration and diversification of sexually selected traits; the mechanisms that mediate trait-preference coevolution are largely unknown. Carotenoids influence female health and reproduction in ways that may alter the costs and benefits of mate choice behaviours and provide a potential biochemical link between the expression of male traits and female preferences. To test this hypothesis, we manipulated the dietary carotenoid levels of captive female house finches (Carpodacus mexicanus) and assessed their mate choice behavior in response to colormanipulated male finches. Selected carotenoid-based male coloration appears in a diversity of taxa, from crabs (Callinectes sapidus; [6]) and fish (Poecilia reticulata; [7]) to birds (Carpodacus mexicanus; [8]), and has become a model system for understanding the costs, benefits, and evolution of male sexual trait expression [9]. Carotenoidbased coloration reveals information about male quality (i.e. diet, health) and female preferences for intense carotenoid-based coloration have been demonstrated in a number of taxa (especially birds; reviewed in [14])
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