Costs and benefits of communal breeding in grey mouse lemurs
Grey mouse lemurs (Microcebus murinus) are small, nocturnal, solitary foraging primates in which females den and creche their young communally. Adults weigh in at only 60-100g. Breeding unit size varies from one to three females and each mother can give birth to one to three young. Males do not contribute to parental care. I am interested in the costs and benefits of rearing young in the same nest. My data collection involved capturing and marking females and young, video recording behaviour within nestboxes, and analysing interactive behaviour contributed from females to pups. Data was collected during the wet season in Kirindy Forest, a western seasonal forest in Madagascar. This research was conducted in collaboration with Dr. Manfred Eberle and Professor Peter Kappeler of the Deutches Primaten Zentrum (German Primate Centre), Gottingen. A popular science article highlighting the fascinating life of grey mouse lemurs can be found in BBC Wildlife Magazine (July 2008; which you can access here) with a shortened and edited version subsequently published in BBC Knowledge Magazine. The Abstract from presentation at the International Primatology Society Conference 2008 is below:
Abstract for Presentation at International Primatology Society Conference 2008
Cooperation and Alloparental Care in the Grey Mouse Lemur (Microcebus murinus): the Costs and Benefits of Babysitting and Beyond
Gilchrist, J.S., Eberle, M., Kappeler, P.M.
Cooperative behaviour should only be employed where inclusive fitness benefits exceed the costs. Alloparental care is one of the most dramatic forms of cooperation. However, within the primates, alloparental care is relatively rare and evidence of costs and benefits to individuals engaging in these behaviours is limited. We test the effects of nest sharing by females with young, on potential correlates of fitness in wild grey mouse lemurs. By filming nests and weighing females and pups, we evaluate time spent in nest by individual females, contribution to care of individual pups (own and non-offspring) by individual females (including nursing, carrying and grooming), and correlation between these behaviours and body mass of females and pups. Thermoregulation is also a factor for these small (<100g) primates, and the relationships between female breeding group size, communal litter size, and nest temperature are also examined. Data was collected over three years and five breeding units of one to three females and up to seven pups. There was no effect of breeding group size (number of females) on pups per female at birth (F1,3=0.08, P=0.79), pup survival (F1,3=1.94, P=0.26), or number of pups per female at independence (F1,3=1.75, P=0.28). Breeding group size had no significant effect on pup weight change (F1,6=0.18, P=0.69) or pup weight at independence (F1,6=0.37, P=0.56). The results suggest that the effects of nest sharing on survival and weight of pups are negligible, but analysis of likely behavioural correlates of fitness suggests there are advantages to females and pups of nest sharing.
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