Helpers: Effects of Experimental Removal on Reproductive Success

Brown, Jerram L.; Brown, Esther R.; Brown, S. D.; Dow, Douglas

doi:10.1126/science.215.4531.421

Cited by 149 publications

(96 citation statements)

References 16 publications

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“…Thus, in the case of helpers at the nest, it is possible to identify a set of territories with equivalent numbers of helpers present and then experimentally remove helpers from some nests, selected at random. Such experimental studies have confirmed the hypothesis that, at least in some species, the presence of helpers at the nest does increase the number of young fledged (Brown et al 1982).…”

Section: Experimental Approachsupporting

confidence: 65%

On the Proper Definition of Cognitive Ethology

Kamil

1998

Animal Cognition in Nature

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Section: Experimental Approachsupporting

confidence: 65%

On the Proper Definition of Cognitive Ethology

Kamil

1998

Animal Cognition in Nature

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“…For example, apparent helper effects on productivity can be non-causal [10,16]; so our predictions might not reflect true helper benefits from helping in groups of varying sizes. Group size manipulations [38] do not resolve this problem because only reductions are possible and they necessarily alter grouping benefits and disrupt social dynamics, making it difficult to verify that reductions in provisioning rates are caused by reductions in helper numbers [11]. Therefore, we used brood size manipulations which can circumvent the above problems [23,24].…”

Section: Discussionmentioning

confidence: 99%

Kin selection, not group augmentation, predicts helping in an obligate cooperatively breeding bird

et al. 2012

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Kin selection theory has been the central model for understanding the evolution of cooperative breeding, where non-breeders help bear the cost of rearing young. Recently, the dominance of this idea has been questioned; particularly in obligate cooperative breeders where breeding without help is uncommon and seldom successful. In such systems, the direct benefits gained through augmenting current group size have been hypothesized to provide a tractable alternative (or addition) to kin selection. However, clear empirical tests of the opposing predictions are lacking. Here, we provide convincing evidence to suggest that kin selection and not group augmentation accounts for decisions of whether, where and how often to help in an obligate cooperative breeder, the chestnut-crowned babbler (Pomatostomus ruficeps). We found no evidence that group members base helping decisions on the size of breeding units available in their social group, despite both correlational and experimental data showing substantial variation in the degree to which helpers affect productivity in units of different size. By contrast, 98 per cent of group members with kin present helped, 100 per cent directed their care towards the most related brood in the social group, and those rearing half/full-sibs helped approximately three times harder than those rearing less/non-related broods. We conclude that kin selection plays a central role in the maintenance of cooperative breeding in this species, despite the apparent importance of living in large groups.

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“…Another option is to remove group members and compare the outcome (e.g. Brown et al 1982;Solomon 1991;Powell & Fried 1992), but here one should be cautious about interpreting the results of such experiments because they change group size as well as helper number (Cockburn 1998;Russell et al 2008).…”

Section: Maternal Effects As Confounds Of Fitness Estimatesmentioning

confidence: 99%

Maternal effects in cooperative breeders: from hymenopterans to humans

Russell

Lummaa

2009

Phil. Trans. R. Soc. B

106

153

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The environment that an offspring experiences during its development can have lifelong consequences for its morphology, anatomy, physiology and behaviour that are strong enough to span generations. One aspect of an offspring's environment that can have particularly pronounced and long-lasting effects is that provided by its parent(s) (maternal effects). Some disciplines in biology have been quicker to appreciate maternal effects than others, and some organisms provide better model systems for understanding the causes and consequences of the maternal environment for ecology and evolution than others. One field in which maternal effects has been poorly represented, and yet is likely to represent a particularly fruitful area for research, is the field of cooperative breeding (i.e. systems where offspring are reared by carers in addition to parent(s)). Here, we attempt to illustrate the scope of cooperative breeding systems for maternal effects research and, conversely, highlight the importance of maternal effects research for understanding cooperative breeding systems. To this end, we first outline why mothers will commonly benefit from affecting the phenotype of their offspring in cooperative breeding systems, present potential strategies that mothers could employ in order to do so and offer predictions regarding the circumstances under which different types of maternal effects might be expected. Second, we highlight why a neglect of maternal strategies and the effects that they have on their offspring could lead to miscalculations of helper/worker fitness gains and a misunderstanding of the factors selecting for the evolution and maintenance of cooperative breeding. Finally, we introduce the possibility that maternal effects could have significant consequences for our understanding of both the evolutionary origins of cooperative breeding and the rise of social complexity in cooperative systems.

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Helpers: Effects of Experimental Removal on Reproductive Success

Cited by 149 publications

References 16 publications

On the Proper Definition of Cognitive Ethology

On the Proper Definition of Cognitive Ethology

Kin selection, not group augmentation, predicts helping in an obligate cooperatively breeding bird

Maternal effects in cooperative breeders: from hymenopterans to humans

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