• H2020
• Excellent Science
• European Research Council

Researchers studying banded mongooses in Uganda have discovered that the mammals are able to discriminate between relatives and non-relatives to avoid inbreeding, even when mating within their own social group.

This study, funded by the European Research Council, is the first to suggest that social animals are able to avoid the costs of inbreeding without relying on unrelated mating partners from other social groups.

Dr Jennifer Sanderson, from the UK’s University of Exeter’s Penryn Campus, has been observing wild banded mongooses to understand how they avoid the negative aspects of inbreeding. She found that whilst most social mammals avoid inbreeding by either not breeding or dispersing to a group of non-relatives, male banded mongooses avoid inbreeding by focusing their mating effort towards females within their extended family to which they are least related. Although the researchers do not yet understand how they avoid inbreeding, the mongooses may use scent, or their highly individual calls, to help them gauge relatedness.

Commenting, Sanderson said: “Wild animals are known to use a variety of tactics to avoid the costs associated with inbreeding, but most of these tactics involve dispersal or waiting to encounter an unrelated immigrant. Our study has shown that both male and female banded mongooses are able to avoid inbreeding while mating within their family group even in the absence of immigration”.

Sanderson collaborated with Dr Hazel Nichols to collect thousands of genetic samples from the Ugandan mongooses which were then analysed at Liverpool John Moores University. Providing her thoughts, Nichols said: “We’ve used a large number of genetic markers to determine the parents of over 1,500 banded mongoose pups. This has allowed us to quantify the occurrence of inbreeding and investigate the tactics used by both male and female banded mongooses to avoid it.”

Sanderson found that when banded mongooses did breed with close relatives the resulting inbred offspring were significantly smaller than their outbred littermates when they emerged from the den for the first time. This finding is indicative of inbreeding depression and highlights the benefits to be gained from avoiding mating with close relatives. Male banded mongooses actively guard females to gain access to mating opportunities, and the study shows this guarding behaviour is preferentially directed towards less closely related females.

According to the University of Exeter’s Professor Michael Cant, who leads the Banded Mongoose Research Project, a combination of behavioural observations and genetic analyses were used to assess inbreeding avoidance in male and female mongooses. Cant commented: “It’s not just the males who actively avoid mating with relatives; we also found that female banded mongooses may avoid inbreeding by upgrading from related mate guards to unrelated mating partners.”

The findings of the 16-year study are published in the journal Molecular Ecology.