Banded mongooses avoid inbreeding when mating with members of the same natal group

Abstract

Inbreeding and inbreeding avoidance are key factors in the evolution of animal societies, influencing dispersal and reproductive strategies which can affect relatedness structure and helping behaviours. In cooperative breeding systems, individuals typically avoid inbreeding through reproductive restraint and/or dispersing to breed outside their natal group. However, where groups contain multiple potential mates of varying relatedness, strategies of kin recognition and mate choice may be favoured. Here, we investigate male mate choice and female control of paternity in the banded mongoose (Mungos mungo), a cooperatively breeding mammal where both sexes are often philopatric and mating between relatives is known to occur. We find evidence suggestive of inbreeding depression in banded mongooses, indicating a benefit to avoiding breeding with relatives. Successfully breeding pairs were less related than expected under random mating, which appeared to be driven by both male choice and female control of paternity. Male banded mongooses actively guard females to gain access to mating opportunities, and this guarding behaviour is preferentially directed towards less closely related females. Guard–female relatedness did not affect the guard's probability of gaining reproductive success. However, where mate‐guards are unsuccessful, they lose paternity to males that are less related to the females than themselves. Together, our results suggest that both sexes of banded mongoose use kin discrimination to avoid inbreeding. Although this strategy appears to be rare among cooperative breeders, it may be more prominent in species where relatedness to potential mates is variable, and/or where opportunities for dispersal and mating outside of the group are limited.

Explaining negative kin discrimination in a cooperative mammal society

“…Older males monopolize mating with estrus females by mate guarding them and aggressively driving away younger, subordinate males (10,11). Previous work shows that both sexes are capable of kin discrimination in the context of mating, supporting the assumption of our model that such discrimination is possible in this system (12). Evictions are relatively common, involve intense, targeted aggression, and result in the forcible mass exclusion of groups (median = 6 individuals) of females (female-only evictions) and, in around half of cases, groups (median = 9 males) of males alongside them (mixed-sex evictions) (13).…”

Heterozygosity but not inbreeding coefficient predicts parasite burdens in the banded mongoose

“…(). The final pedigree used both Masterbayes 2.51 (Hadfield, Richardson & Burke, ) and COLONY 2.0.5.7 (Jones & Wang, ) to infer parentage (1570 maternities and 1476 paternities) at a probability of ≥0.8 across a 14‐year period (Sanderson et al ., ). Although no pedigree collected from the wild can be complete due to the presence of founding members and immigrants, our pedigree has very high coverage of the population (of the 61 individuals sample for parasite analysis, 56 were assigned both parents and grandparents).…”

“…This becomes particularly pronounced when the history of founding and immigrant members of a population are unknown (Keller et al ., ), as is the case for the study population. Thus, standardized multi‐locus heterozygosity (sMLH) was calculated from raw allele frequencies of the microsatellite markers (Sanderson et al ., ). In order to gain a comparable assessment of heterozygosity for individuals with parasite data, we removed the loci with less than 90% coverage.…”

“…A total of 14.3% of pups appear moderately inbred (ƒ = 0.125) and 8% show inbreeding coefficients of ƒ ≥ 0.25, indicating breeding between first‐order relatives (Nichols et al ., ). Both inbreeding avoidance and inbreeding depression also occur; within‐group breeding pairs appear less related than would be predicted by chance (Sanderson et al ., ) and pups sired by extra‐group fathers are significantly heavier at birth, more heterozygous and more likely to survive than those of within‐group paternity (Nichols, Cant & Sanderson, ; Sanderson et al ., ).…”

Genetic population structure and relatedness in the narrow‐striped mongoose (Mungotictis decemlineata), a socialMalagasy carnivore with sexual segregation

“…2012, 2015; Sanderson et al. 2015). In contrast, much less is known about genetic structure and reproductive systems of the so‐called “solitary” mongooses, which often display gregarious tendencies (e.g., Galerella sanguinea : Waser et al.…”