Mates of Competitive Females: The Relationships between Female Aggression, Mate Quality, and Parental Care

Kristal E Cain

doi:10.1155/2014/319567

Abstract

Though rarely mate-limited, females in a wide variety of species express traits commonly associated with mate competition in males. Recent research has shown that these competitive traits (ornaments, armaments, and intense aggression) often function in the context of female-female competition for nonsexual reproductive resources and are often positively related to reproductive success. Increased success could occur because competitive females acquire limited ecological resources (nest sites, territories, etc.) or because they pair with high quality males, that is, older, more ornamented, or more parental males. Further, males paired with aggressive/low care females may compensate by increasing their paternal efforts. Here, I examined patterns of social pairing and parental care in free-living dark-eyed juncos (Junco hyemalis), a biparental songbird. I found no detectable relationship between female competitive behavior (aggression) and male quality (age, size, or ornamentation) or male provisioning. Thus, neither of the mate choice hypotheses (females compete for males or males prefer aggressive females) was supported. Instead, these results suggest that females compete for nonsexual resources and mate quality is a secondary consideration. I also found a negative relationship between male and female provisioning rates, suggesting that partners adjust their level of parental effort in response to their partner’s efforts.

Highlights

Though females are rarely mate-limited, they are often limited by access to other important reproductive resources such as territories, ovoposition sites, and dominance rank [1,2,3,4,5,6]
Social selection argues that competition for any important resource, sexual or nonsexual, can lead to the evolution of ornaments, armaments, intense aggression, or complex acoustic signals, hereafter referred to as competitive traits [1, 2]
Recent empirical work examining the functional consequences of female expression of competitive traits supports the predictions of social selection; females with greater degree of trait expression often have improved reproductive success [1, 2, 4, 6, 7]

Summary

Introduction

Though females are rarely mate-limited, they are often limited by access to other important reproductive resources such as territories, ovoposition sites, and dominance rank [1,2,3,4,5,6]. Recent empirical work examining the functional consequences of female expression of competitive traits supports the predictions of social selection; females with greater degree of trait expression often have improved reproductive success [1, 2, 4, 6, 7]. This pattern is interesting because in many vertebrates increased trait expression is associated with a reduction in some forms of maternal care [8,9,10,11,12,13]. In order to develop a better understanding of the selective forces mediating female competitive traits expression we need to examine both simultaneously

Methods

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Discussion

Conclusion