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Lack of intergenerational reproductive conflict, rather than lack of inclusive fitness benefits, explains absence of post-reproductive lifespan in long-finned pilot whales

Jack L McCormack, Kevin Arbuckle Orcid Logo, Karen Fullard, William Amos, Hazel Nichols Orcid Logo

Behavioral Ecology, Volume: 34, Issue: 6, Pages: 950 - 959

Swansea University Authors: Kevin Arbuckle Orcid Logo, Hazel Nichols Orcid Logo

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DOI (Published version): 10.1093/beheco/arad062

Abstract

Life-history theory suggests that individuals should reproduce until death, yet females of a small number of mammals live for a significant period after ceasing reproduction, a phenomenon known as post-reproductive lifespan. It is thought that the evolution of this trait is facilitated by increasing...

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Published in: Behavioral Ecology
ISSN: 1045-2249 1465-7279
Published: Oxford University Press (OUP) 2023
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa64196
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Abstract: Life-history theory suggests that individuals should reproduce until death, yet females of a small number of mammals live for a significant period after ceasing reproduction, a phenomenon known as post-reproductive lifespan. It is thought that the evolution of this trait is facilitated by increasing local relatedness throughout a female’s lifetime. This allows older females to gain inclusive fitness through helping their offspring (known as a mother effect) and/or grandoffspring (known as a grandmother effect), rather than gaining direct fitness through reproducing. However, older females may only benefit from stopping reproducing when their direct offspring compete with those of their daughters. Here, we investigate whether a lack of post-reproductive lifespan in long-finned pilot whales (Globicephala melas) results from minimal benefits incurred from the presence of older females, or from a lack of costs resulting from mother–daughter co-reproduction. Using microsatellite data, we conducted parentage analysis on individuals from 25 pods and find that younger females were more likely to have offspring if their mother was present in their pod, indicating that mothers may assist inexperienced daughters to reproduce. However, we found no evidence of reproductive conflict between co-reproducing mothers and daughters, indicating that females may be able to reproduce into old age while simultaneously aiding their daughters in reproduction. This highlights the importance of reproductive conflict in the evolution of a post-reproductive lifespan and demonstrates that mother and grandmother effects alone do not result in the evolution of a post-reproductive lifespan.
Keywords: Cetaceans, costs vs. benefits, demography, post-reproductive lifespan, social structure
College: Faculty of Science and Engineering
Funders: Swansea University
Issue: 6
Start Page: 950
End Page: 959