Causes, consequences and evolution of inbreeding tolerance and avoidance in a cooperative mammal

• Applicant: Professor Dr. Joseph Hoffman
• Subject Area: Evolutionary Cell and Developmental Biology (Zoology) ; Sensory and Behavioural Biology ; Evolution, Anthropology ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263742823

It is well known that inbreeding sometimes occurs in wild populations, and that this usually incurs a fitness cost, but the impacts of inbreeding may go much further than inbreeding depression. At its most basic level, inbreeding increases relatedness between group members, which may in turn increase the benefits of cooperation. This idea, whilst controversial, has received considerable theoretical support. In cooperatively breeding species, inbred individuals may be more closely related to other group members and hence may be more likely to help, or to receive help, than their outbred counterparts. Consequently, inbreeding could have important impacts on the distribution of helping behavior within social groups. Furthermore, although the impacts of inbreeding depression have been much studied, the underlying causes of inbreeding are poorly understood. Little is known, for example, about the demographic factors that can lead to high levels of relatedness between breeders. The exact circumstances under which individuals are able to avoid inbreeding also remain unclear.We propose to investigate the causes and consequences of inbreeding using rich, multigenerational data from a long-term study of a highly cooperative mammal, the banded mongoose, Mungos mungo. Our previous work on this system has revealed considerable intraspecific variation in both the propensity to inbreed and the realised level of inbreeding, making it ideally suited to studying the natural history of inbreeding. Consequently, we will exploit a large existing molecular dataset of around 2000 individuals genotyped at 40 microsatellite loci to construct a pedigree up to 17 generations deep. This will be used to establish levels of inbreeding and relatedness, which in turn will be linked to detailed individual-based behavioural and phenotypic data collected continuously over almost two decades.This wealth of pedigree and life-history data will be used to explore the social and genetic factors that shape inbreeding behaviour, to establish if and how females avoid inbreeding, and to determine if whether helping behaviour can mitigate the costs of inbreeding depression. Finally, we will exploit the unique 'escorting' system of this species, in which each offspring is protected, fed and groomed by a single adult, to test the hypothesis that helpers preferentially direct care towards closely related, inbred pups. If so, this would provide the first empirical demonstration to our knowledge of inbreeding facilitating kin selection in a cooperatively breeding mammal.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Participating Persons: Professor Dr. Michael Cant; Privatdozentin Hazel Nichols, Ph.D.