The evolution of male parental care in mammals

West, Hannah E. R.

Biological sciences
April 2017

Thesis or dissertation

© 2017 Hannah E R West. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Males care for offspring across a diverse range of taxa. Why males give up mating opportunities and spend time and energy caring for offspring is unclear, especially when females already provide parental care. The evolutionary drivers for biparental care are currently uncertain, as are the evolutionary consequences of male care on female and offspring fitness. Using modern phylogenetic comparative methods, I test hypotheses on the evolution of biparental care in a sample of over 500 mammalian species while considering the diversity in parental care behaviours. Both male care and monogamy occur in species where levels of paternity are high, but only monogamy associates with reduced investment in sperm competition traits. Male care also has energetic benefits for females and offspring; females have higher fecundity and offspring faster growth in species with biparental care, in support of the ‘load-lightening’ hypothesis. I find strong support for the hypothesis that monogamy drives the evolution of male care but only for behaviours that provide fecundity benefits, while behaviours unrelated to female fecundity may either precede or follow monogamy. However, I find no support for the hypothesis that infanticide by males promotes the evolution of male care. Lastly, I investigate whether care by non-parental helpers exhibit similar associations with life history traits as male care and find that care by helpers associates with increased fecundity, but by influencing different times of the female reproductive cycle. Overall I identify a two-step process of evolution between male care and social monogamy, with care behaviours which do not confer fecundity benefits facilitating the evolution of social monogamy and higher paternity levels, which subsequently promote the evolution of further care behaviours with higher energetic benefits. Thus, this research demonstrates the importance of considering the care behaviour performed, the time of female reproduction at which it is performed, and the identity of the carer, in studies investigating the evolution of parental care.

School of Environmental Sciences, The University of Hull
Capellini, Isabella
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University of Hull
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