Data from: Fine-scale spatiotemporal patterns of genetic variation reflect budding dispersal coupled with strong natal philopatry in a cooperatively breeding mammal

The relatedness structure of animal populations is thought to be a critically important factor underlying the evolution of mating systems and social behaviours. While previous work has shown that population structure is shaped by many biological processes, few studies have investigated how these factors vary over time. Consequently, we explored the fine-scale spatiotemporal genetic structure of an intensively studied population of cooperatively breeding banded mongooses (Mungos mungo) over a ten-year period. Overall population structure was strong (average Fst = 0.129) but groups with spatially overlapping territories were not more genetically similar to one another than non-contiguous groups. Instead, genetic differentiation was associated with historical group-fission (budding) events, with new groups diverging from their parent groups over time. Within groups, relatedness was high within but not between the sexes, although the latter increased over time since group formation due to group founders being replaced by philopatric young. This trend was not mirrored by a decrease in average offspring heterozygosity over time, suggesting that close inbreeding may often be avoided, even when immigration into established groups is virtually absent and opportunities for extra-group matings are rare. Fine-scale spatiotemporal population structure could have important implications in social species, where relatedness between interacting individuals is a vital component in the evolution of patterns of inbreeding avoidance, reproductive skew and kin-selected helping and harming.

动物种群的亲缘关系结构被视为交配系统与社会行为演化的关键驱动因素。尽管已有研究表明种群结构受多种生物过程塑造，但极少有研究探讨此类因子随时间的变化规律。为此，本研究针对一个被长期深入研究的合作繁殖型缟獴（Mungos mungo）种群，开展了为期十年的精细时空尺度遗传结构分析。整体种群遗传结构分化显著（平均Fst=0.129），但领地空间重叠的群组间遗传相似性并未高于非邻接群组。与之相反，遗传分化与历史群组裂变（萌芽式分裂）事件密切相关，新群组会随时间推移与亲本组群产生遗传分化。群组内部，同性别个体间亲缘关系较高，而异性别间则无此特征；不过异性别间的亲缘关系会随群组建成后的时长逐渐升高，这是由于群组创建者会被留居的后代所取代。这一亲缘关系升高的趋势并未伴随子代平均杂合度随时间下降的现象，这表明即便几乎无外来个体迁入已建成的群组，且群组外交配的机会极少，种群仍可普遍避免高度近交。精细时空尺度的种群结构对社会性物种具有重要演化意义：互动个体间的亲缘关系，是近交回避模式、生殖偏倚以及亲缘选择下互助与伤害行为演化的核心要素。