Bateman's principle is reversed in a cooperatively breeding bird

Apakupakul, Kathleen; Rubenstein, Dustin R.

doi:10.1098/rsbl.2015.0034

Cited by 19 publications

(25 citation statements)

References 21 publications

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“…Selection on traits used for access to mates, resources or social rank may be similarly strong in both sexes in social vertebrates and insects with totipotent workers because intrasexual competition is similarly strong in females and males [9,11,12]. Here, we show that patterns of sexual dimorphism in secondary sexual characteristics do not just differ between social and non-social species (sensu [11]), but instead vary Table 2.…”

Section: Discussionmentioning

confidence: 66%

“…In such systems, both males and females may experience strong intrasexual competition for mates or breeding opportunities, and thus females may have equally high (or even higher) variance in reproductive success than males [8][9][10][11]. Ultimately, selection on the same competitive traits used in intrasexual competition for access to mates, resources or social rank can be as strong in females as in males of these social species [9,11,12]. For example, cooperatively breeding birds are generally not sexually dimorphic [13], and sexual dimorphism in plumage and body size is reduced in cooperative African starlings (Sturnidae) compared with their non-cooperative relatives [11].…”

Section: Introductionmentioning

confidence: 99%

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Reproductive skew drives patterns of sexual dimorphism in sponge-dwelling snapping shrimps

2015

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Sexual dimorphism is typically a result of strong sexual selection on male traits used in male-male competition and subsequent female choice. However, in social species where reproduction is monopolized by one or a few individuals in a group, selection on secondary sexual characteristics may be strong in both sexes. Indeed, sexual dimorphism is reduced in many cooperatively breeding vertebrates and eusocial insects with totipotent workers, presumably because of increased selection on female traits. Here, we examined the relationship between sexual dimorphism and sociality in eight species of Synalpheus snapping shrimps that vary in social structure and degree of reproductive skew. In species where reproduction was shared more equitably, most members of both sexes were physiologically capable of breeding. However, in species where reproduction was monopolized by a single individual, a large proportion of females-but not males-were reproductively inactive, suggesting stronger reproductive suppression and conflict among females. Moreover, as skew increased across species, proportional size of the major chela-the primary antagonistic weapon in snapping shrimps-increased among females and sexual dimorphism in major chela size declined. Thus, as reproductive skew increases among Synalpheus, female-female competition over reproduction appears to increase, resulting in decreased sexual dimorphism in weapon size.

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Section: Discussionmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Reproductive skew drives patterns of sexual dimorphism in sponge-dwelling snapping shrimps

2015

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“…This is not surprising, since most nest failure in superb starlings is the result of predation [19], not the lack of parental care. The most important predictor of high lifetime reproductive success in superb starlings is the number of times a female breeds [20], so simply being able to breed more often because kin are present may be vital to female fitness.…”

Section: Discussionmentioning

confidence: 99%

The fitness consequences of kin-biased dispersal in a cooperatively breeding bird

Pollack

Rubenstein

2015

Biol. Lett.

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Cooperative alliances among kin may not only lead to indirect fitness benefits for group-living species, but can also provide direct benefits through access to mates or higher social rank. However, the immigrant sex in most species loses any potential benefits of living with kin unless immigrants disperse together or recruit relatives into the group in subsequent years. To look for evidence of small subgroups of related immigrants within social groups (kin substructure), we used microsatellites to assess relatedness between immigrant females of the cooperatively breeding superb starling, Lamprotornis superbus. We determined how timing of immigration led to kin subgroup formation and if being part of one influenced female fitness. Although mean relatedness in groups was higher for males than females, 26% of immigrant females were part of a kin subgroup with a sister. These immigrant sibships formed through kin recruitment across years more often than through coalitions immigrating together in the same year. Furthermore, females were more likely to breed when part of a kin subgroup than when alone, suggesting that female siblings form alliances that may positively influence their fitness. Ultimately, kin substructure should be considered when determining the role of relatedness in the evolution of animal societies.

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“…We used this measurement rather than lifetime reproductive success (i.e., total number of offspring fledged) because high nest predation rates and unpredictable breeding conditions in this population make this an unreliable indicator of the number of breeding opportunities an individual obtained. Moreover, we know from previous work in this system that the number of seasons breeding is the strongest predictor of lifetime reproductive success (Apakupakul and Rubenstein, 2015). Thus, our selected predictor variables (i.e., age, current status, proportion of seasons breeding) are all believed to be correlated with fitness and dominance status in superb starlings.…”

Section: Song Diversity Analysesmentioning

confidence: 99%

Song in a Social and Sexual Context: Vocalizations Signal Identity and Rank in Both Sexes of a Cooperative Breeder

et al. 2016

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In most songbirds, both sexes produce calls, or short vocalizations used to coordinate behaviors and maintain social cohesion. In contrast, songs are longer, more elaborate vocalizations typically only produced by males in behavioral contexts shaped by sexual selection operating through female choice. However, both males and females sing in many cooperatively breeding species, including the superb starling (Lamprotornis superbus). In this species, both sexes produce songs and calls composed of sequences of temporally discrete elements called motifs. Calls signal social group and individual identity, but the function of songs is currently unknown. Because superb starlings often sing in groups, song could be used not only in a sexual context, but also to signal identity and rank within the separate dominance hierarchies observed in males and females. To determine whether songs are used in mate attraction (sexually selected) and/or to influence social rank (socially selected), we compared song diversity with three potential indicators of fitness and dominance: social status, the number of seasons spent breeding, and age. We found that age is correlated with song diversity in both males and females, suggesting that (1) these signals serve similar purposes in both sexes, and (2) song diversity is likely the result of selection by both mutual mate choice and social competition. To test whether songs carry a signal of individuality, we applied spectrogram dynamic time warping to measure pairwise similarity among song motifs, and then calculated motif similarity within and between individuals. We found that motif similarity is higher within individuals than between individuals, suggesting that songs signal individual identity, which may help to establish social rank. These results are consistent with the hypothesis that superb starling vocal behavior in each sex is shaped by both social and sexual selection. Additionally, because call motifs are also used in songs, our data suggest that at least some vocal building blocks have evolved to convey multiple signaler traits and to facilitate complex social and sexual interactions in different contexts.

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Bateman's principle is reversed in a cooperatively breeding bird

Cited by 19 publications

References 21 publications

Reproductive skew drives patterns of sexual dimorphism in sponge-dwelling snapping shrimps

Reproductive skew drives patterns of sexual dimorphism in sponge-dwelling snapping shrimps

The fitness consequences of kin-biased dispersal in a cooperatively breeding bird

Song in a Social and Sexual Context: Vocalizations Signal Identity and Rank in Both Sexes of a Cooperative Breeder

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