Thatcher Amber, Insel Nathan
Department of Psychology, University of Montana, Missoula, Montana, USA.
Department of Psychology, Wilfrid Laurier University, Waterloo, Ontario, Canada.
Ethology. 2024 Aug;130(8). doi: 10.1111/eth.13487. Epub 2024 Jun 4.
Degus () are a highly gregarious species of caviomorph rodent native to South America. Kinship does not appear to play a role in degu social structure, and alloparenting is often observed between unrelated females. We hypothesize that female degus readily establish new, cooperative peer relationships. Here we examined changes in dyadic behavior as individuals became more familiar, testing the prediction that interactions between female strangers would quickly resemble those of cagemates. Adult degus underwent a several week series of 20 minute "reunion" social exposures, interleaving reunions with initial strangers and, as a control, familiar cagemates. Males showed initially higher levels of interaction with strangers that converged with cagemate levels over experience. Females could be split into two groups: those that consistently interacted more with strangers (SC-HIGH) and those that did not (SC-LOW); however, unlike males, the higher interaction levels observed between strangers did not change with familiarity. Following 10 reunion sessions female strangers were housed together to create "new cagemates". Even after co-housing, SC-HIGH (but not SC-LOW) females continued to interact more with the relatively unfamiliar peer than their prior cagemate, particularly in face-to-face and rear-sniffing interactions. A final set of reunions with new strangers found that individual differences in female responses to social novelty were preserved. These results reveal sex differences in the rules relating familiarization to social relationships in degus, and that female predispositions toward cooperation may be due to inherent responses to new individuals more than to how they negotiate relationships over time.
八齿鼠是一种原产于南美洲的高度群居的豚鼠型啮齿动物。亲缘关系似乎在八齿鼠的社会结构中不起作用，经常能观察到非亲属雌性之间存在异亲抚育行为。我们推测雌性八齿鼠能够轻易建立新的合作同伴关系。在此，我们研究了随着个体之间变得更加熟悉，二元行为的变化情况，检验了陌生雌性之间的互动会迅速类似于同笼伙伴之间互动的预测。成年八齿鼠经历了为期数周、每次20分钟的“重逢”社交接触系列，将与陌生初始个体的重逢与，作为对照的，熟悉的同笼伙伴的重逢穿插进行。雄性最初与陌生人的互动水平较高，随着经验的积累，这一水平与同笼伙伴的水平趋于一致。雌性可分为两组：一组与陌生人的互动始终较多（SC-HIGH组），另一组则不然（SC-LOW组）；然而，与雄性不同的是，陌生人之间观察到的较高互动水平并不会随着熟悉程度而改变。在进行10次重逢后，将陌生雌性放在一起饲养，形成“新的同笼伙伴”。即使在共同饲养之后，SC-HIGH组（而非SC-LOW组）的雌性与相对不熟悉的同伴的互动仍然多于其之前的同笼伙伴，尤其是在面对面和嗅探尾部的互动中。最后一组与新陌生人的重逢发现，雌性对社交新奇性的反应存在个体差异。这些结果揭示了八齿鼠在将熟悉程度与社会关系联系起来的规则方面存在性别差异，并且雌性的合作倾向可能更多地归因于对新个体的固有反应，而非它们如何随着时间推移协商关系。
