Group augmentation on trial: helpers in small groups enhance antipredator defence of eggs.

García-Ruiz, Irene; Taborsky, Michael (2022). Group augmentation on trial: helpers in small groups enhance antipredator defence of eggs. Biology Letters, 18(10), p. 20220170. The Royal Society 10.1098/rsbl.2022.0170

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Mechanisms selecting for the evolution of cooperative breeding are hotly debated. While kin selection theory has been the central paradigm to explain the seemingly altruistic behaviour of non-reproducing helpers, it is increasingly recognized that direct fitness benefits may be highly relevant. The group augmentation hypothesis proposes that alloparental care may evolve to enhance group size when larger groups yield increased survival and/or reproductive success. However, there is a lack of empirical tests. Here we use the cooperatively breeding cichlid fish Neolamprologus pulcher, in which group size predicts survival and group stability, to test this hypothesis experimentally by prompting two cooperative tasks: defence against an egg predator and digging out sand from the breeding shelter. We controlled for alternative mechanisms such as kin selection, load lightening and coercion. As predicted by the group augmentation hypothesis, helpers increased defence against an egg predator in small compared with large groups. This difference was only evident in large helpers owing to size-specific task specialization. Furthermore, helpers showed more digging effort in the breeding chamber compared with alternative personal shelters, indicating that digging is an altruistic service to the dominant breeders.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Biology > Institute of Ecology and Evolution (IEE) > Behavioural Ecology
08 Faculty of Science > Department of Biology > Institute of Ecology and Evolution (IEE)

UniBE Contributor:

García Ruiz, Irene, Taborsky, Michael

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 590 Animals (Zoology)

ISSN:

1744-9561

Publisher:

The Royal Society

Language:

English

Submitter:

Pubmed Import

Date Deposited:

06 Oct 2022 12:42

Last Modified:

05 Dec 2022 16:26

Publisher DOI:

10.1098/rsbl.2022.0170

PubMed ID:

36196551

Uncontrolled Keywords:

Neolamprologus pulcher altruism antipredator defence cooperative breeding group size shelter digging

BORIS DOI:

10.48350/173521

URI:

https://boris.unibe.ch/id/eprint/173521

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