Neighbours' Breeding Success and the Sex Ratio of Their Offspring Affect the Mate Preferences of Female Zebra Finches

Frédérique Dubois,Paul Sunnucks,Dominique Drullion

doi:10.1371/journal.pone.0029737

Abstract

Several hypotheses on divorce predict that monogamous pairs should split up more frequently after a breeding failure. Yet, deviations from the expected pattern “success-stay, failure-leave” have been reported in several species. One possible explanation for these deviations would be that individuals do not use only their own breeding performance (i.e., private information) but also that of others (i.e., public information) to decide whether or not to divorce. To test this hypothesis, we investigated the relative importance of private and public information for mate choice decisions in female zebra finches (Taeniopygia guttata).We manipulated the reproductive performance of breeding pairs and measured females' preferences for their mate and the neighbouring male first following pair formation and then seven weeks later when all females had laid eggs and the young were independent. Although all females reduced their preference for their mate after a breeding failure, the decrease was significant only when the neighbouring pair had reproduced successfully. Furthermore, there was no evidence that females biased the sex ratio of their offspring according to their mate's attractiveness. On the other hand, after reproduction, both successful and unsuccessful females increased their preferences for males who had produced a larger proportion of sons. Despite the fact that other mechanisms may have also contributed to our findings, we suggest that females changed their mate preferences based on the proportion of sons produced by successful males, because offspring sex ratio reflects the male's testosterone level at the moment of fertilization and hence is an indicator of his immune condition.

Highlights

Mate choice may incur important costs, such as time and energy spent in searching for and assessing potential partners [1]
As a consequence the mean percent of time spent by females in front of their breeding partner before mating was significantly higher than 50% (72.964.8%; unilateral t-test: t17 = 4.239, P,0.001), and females in successful pairs spent less choosing time in front of their breeding partner compared to those in unsuccessful pairs, the difference was not significant (mean percent of time successful females spent with their breeding partner (X 6 SE): successful females : 63.967.2%, unsuccessful females: 77.365.9%, t-test: t16 = 21.370, P = 0.190)
Almost all females strongly preferred their breeding partner over the neighbouring male before reproduction, only those that had reproduced successfully maintained their initial preference after mating. Unsuccessful females increased their preference for the neighbouring male, but the increase was significant only when the neighbouring pair had reproduced successfully

Summary

Introduction

Mate choice may incur important costs, such as time and energy spent in searching for and assessing potential partners [1]. Individuals could use the cues provided by conspecifics either to find a new mate directly [4] or to assess the probability of improving their own breeding situation [5] In this case, only pairs whose breeding performance is below the population mean would split, while those above the population mean would be maintained, regardless of the absolute reproductive success of the pair. Doligez et al [15] found that the immigration rate of Collared flycatchers (Ficedula albicollis) was higher when the local breeding success of the site was experimentally increased, while the proportion of emigrants increased when local offspring quantity or quality decreased Both departure and settlement decisions, varied among individuals depending on their previous breeding experience and were affected by private information [15]

Methods

Results

Conclusion