Reproductive competition and the evolution of extreme birth synchrony in a cooperative mammal

Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, Cornwall TR10 9EZ, UK.
Biology letters (Impact Factor: 3.25). 02/2011; 7(1):54-6. DOI: 10.1098/rsbl.2010.0555
Source: PubMed


Reproductive events in animal societies often show a high degree of temporal clustering, but the evolutionary causes of this synchronization are poorly understood. Here, we suggest that selection to avoid the negative effects of competition with other females has given rise to a remarkable degree of birth synchrony in the communal-breeding banded mongoose (Mungos mungo). Within banded mongoose groups, births are highly synchronous, with 64 per cent of females giving birth on exactly the same night. Our results indicate that this extreme synchrony arises because offspring suffer an increased risk of infanticide if their mother gives birth before other females, but suffer in competition with older littermates if their mother gives birth after them. These findings highlight the important influence that reproductive competition can have for the evolution of reproductive synchrony.

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    • "Firstly, if all females within a social group or within an area of habitat come into oestrus at around the same time, they may be able to attract more males, thereby gaining better choice of potential mates. Secondly, there may be benefits of birth synchrony to offspring care and survival, as females within a group giving birth at same time may allow opportunities for allomothering (Schulte, 2000), and reduce individual risk of infanticide (Hodge et al., 2011;Poikonen et al., 2008) or predation (Gregg et al., 2001;Sinclair et al., 2000). This phenomenon of oestrous synchrony has long been suspected in elephants (Bechert et al., 1999;Dublin, 1983;Poole, 1989;Rasmussen and Schulte, 1998;Slade et al., 2003), and has recently been demonstrated in captive African elephants (Weissenböck et al., 2009). "
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    • "Male mate choice is also predicted to occur where there is variation in female quality and where receptive females are encountered simultaneously (Edward & Chapman 2011). Indeed, high levels of promiscuity within banded mongoose societies mean that males have access to females which vary in genetic compatibility, and the high degree of female reproductive synchrony seen within banded mongoose groups (Hodge et al. 2011) means that males do encounter receptive females simultaneously. The extent to which females synchronize breeding within groups could in fact promote male choice even in the absence of high male reproductive investment as male mating opportunities are limited by the fact that they can only guard one female at a time. "
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