More ornamented females produce higher-quality offspring in a socially monogamous bird: an experimental study in the great tit (Parus major)

Vladimír Remeš,Beata Matysioková

doi:10.1186/1742-9994-10-14

Abstract

IntroductionAnimals are often conspicuously colored and explanations range from aposematism and mimicry to sexual selection. Although sexual selection explains vivid coloration in males, functional significance of vivid coloration in females of socially monogamous species remains unclear. The hypothesis of mutual mate choice predicts that more ornamented females produce offspring of higher quality. We tested this prediction in the great tit (Parus major), a small, insectivorous, socially monogamous passerine.ResultsIn both females and males we quantified three ornaments that have been hypothesized to have signaling role in this species (size of black breast stripe, carotenoid chroma of yellow breast feathers, immaculateness of the white cheek). We swapped broods between nests soon after hatching, thus separating genetic plus pre-hatching vs. post-hatching effects on offspring performance. Body mass of offspring at 14 days of age was positively related to the area of black breast stripe of genetic mothers. Immune response to a novel antigen (phytohaemagglutinin) at 14 days of age was positively related to the immaculateness of the white cheek patch of both genetic and foster mothers.ConclusionsWe showed that females with more elaborate ornaments produced higher-quality offspring and we discuss potential proximate mechanisms of these relationships. We conclude that as more elaborate ornaments were reliable signals of offspring quality, direct selection by male mate choice might have been responsible for the evolution and/or maintenance of these signaling traits in females.

Highlights

Animals are often conspicuously colored and explanations range from aposematism and mimicry to sexual selection
Female ornaments and offspring performance Body mass of offspring at 14d of age was positively related to the area of black breast stripe of genetic mothers; there were strong effects of tarsus length, year, and brood size manipulation (Table 1, Figure 2)
The relationship between nestling body mass and breast stripe of genetic mothers was not confounded by female size, because the correlation between female size and breast stripe area was low (r = 0.17, P = 0.13) and the analysis was controlled for offspring tarsus length

Summary

Introduction

Animals are often conspicuously colored and explanations range from aposematism and mimicry to sexual selection. The leading hypothesis for the evolution of conspicuous color patterns has been sexual selection [4]. Mutual choice of partners can lead even in socially monogamous species to the evolution of ornaments signaling individual quality in terms of good genes or parenting abilities [15,16]. This last hypothesis assumes that more ornamented females are of higher heritable quality (survival, resistance to parasites etc.) and/or provide better parental care in terms of positive effects on offspring quality and survival

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