School of Animal, Plant & Environmental Sciences, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa.
IPHC, UNISTRA, CNRS, 23 rue du Loess, Strasbourg 67200, France.
Proc Biol Sci. 2024 Oct;291(2032):20241534. doi: 10.1098/rspb.2024.1534. Epub 2024 Oct 2.
Many mammal species are thought to adopt solitary living owing to mothers becoming intolerant of adult offspring and the occurrence of social intolerance between adults. However, field studies on how solitary mammals interact are rare. Here we show that solitary living can occur without social intolerance. Over 3 years, we recorded interactions between free-living bush Karoo rats () and conducted dyadic encounter experiments between kin and non-kin female neighbours, both in a neutral test arena and in field intruder experiments. Social interactions were rare (230/2062 observations), and they were aggressive in only 34% of cases. In dyadic encounters, mothers interacted amicably with young offspring. Aggression between mothers and offspring was almost absent. This mother-offspring relationship remained amicable even after adult offspring had dispersed. Aggression between neighbouring adult females was low in neutral arena tests, independent of kinship and season. However, in the field, females reacted more aggressively towards non-kin than kin intruders, especially during the breeding season. Tolerance between mothers and adult offspring indicates that aggression is not the mechanism leading to dispersal and solitary living. We found a solitary social system characterized by social tolerance, suggesting that dispersal and lack of social attraction rather than aggression can lead to solitary living.
许多哺乳动物物种被认为是独居的，这是由于母亲对成年后代的容忍度降低，以及成年个体之间出现社会不容忍现象。然而，关于独居哺乳动物如何相互作用的野外研究却很少。在这里，我们表明，独居生活可以在没有社会不容忍的情况下发生。在 3 年多的时间里，我们记录了自由生活的 Bush Karoo 大鼠（）之间的相互作用，并在中性测试场地和野外入侵者实验中，对亲缘关系和非亲缘关系的雌性邻居进行了对偶遭遇实验。社会互动很少（230/2062 次观察），只有 34%的情况下是攻击性的。在对偶遭遇中，母亲与幼崽友好互动。母亲和后代之间的攻击性几乎不存在。即使成年后代已经分散，这种母子关系仍然保持友好。在中性竞技场测试中，相邻成年雌性之间的攻击性较低，与亲缘关系和季节无关。然而，在野外，雌性对非亲缘入侵者比对亲缘入侵者反应更激烈，尤其是在繁殖季节。母亲和成年后代之间的容忍表明，攻击性不是导致分散和独居的机制。我们发现了一种以社会容忍为特征的独居社会系统，这表明分散和缺乏社会吸引力而不是攻击性可能导致独居。
