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Costly sons do not lead to adaptive sex ratio adjustment in pilot whales, Globicephala melas

Nichols, HJ and Fullard, K and Amos, W (2014) Costly sons do not lead to adaptive sex ratio adjustment in pilot whales, Globicephala melas. ANIMAL BEHAVIOUR, 88. pp. 203-209. ISSN 0003-3472

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Abstract

Maternal investment in reproduction and parental care is an important determinant of both offspring and maternal fitness. However, optimal investment strategies may differ depending on offspring sex, potentially resulting in a sex-biased distribution of maternal resources or adaptive variation in offspring sex-ratio. We used morphometric and genetic data collected from over 3400 long-finned pilot whales Globicephala melas in 40 pods to investigate whether females experience differential costs of producing sons and daughters and whether they differentially invest in male and female offspring. We found that male calves grow faster than female calves during the first five years of life, suggesting that sons may require greater investment from lactating mothers. This appears to result in mothers experiencing a higher cost to future reproductive opportunities when producing male offspring as the presence of dependent sons (but not daughters) reduced the probability that a female would be pregnant. Despite these costs, we found no evidence that mothers adaptively adjust their investment in sons and daughters according to their body condition or their social and physical environment. These results suggest that mothers may be constrained from biasing investment in the sexes, or that additional benefits may be masking such costs.

KEY WORDS: cetacean, Globicephala melas, group size, maternal investment, reproductive costs, reproductive success, sex-ratio

Item Type: Article
Uncontrolled Keywords: 06 Biological Sciences, 07 Agricultural And Veterinary Sciences, 17 Psychology And Cognitive Sciences
Subjects: B Philosophy. Psychology. Religion > BF Psychology
R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
S Agriculture > SF Animal culture
Divisions: Natural Sciences and Psychology
Publisher: Elsevier
Related URLs:
Date Deposited: 03 Jun 2015 10:43
Last Modified: 03 Jun 2015 10:43
DOI or Identification number: 10.1016/j.anbehav.2013.12.015
URI: http://researchonline.ljmu.ac.uk/id/eprint/1349

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