King Wendy J, Forsyth David M, Coulson Graeme, Festa-Bianchet Marco
School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia.
School of BioSciences, University of Melbourne, Parkville, Victoria, Australia.
PLoS One. 2015 May 13;10(5):e0125182. doi: 10.1371/journal.pone.0125182. eCollection 2015.
Adoption is rare in animals and is usually attributed to kin selection. In a 6-year study of eastern grey kangaroos (Macropus giganteus), 11 of 326 juveniles were adopted. We detected eight adoptions by observing behavioural associations and nursing between marked mothers and young and three more by analysing the relatedness of mothers and young using microsatellite DNA. Four adoptions involved reciprocal switches and three were by mothers whose own pouch young were known to subsequently disappear. Adoptive mothers were not closely related to each other or to adoptees but adoptive mothers and young associated as closely as did biological pairs, as measured by half-weight indices. Switch mothers did not associate closely. Maternal age and body condition did not influence the likelihood of adoption but females were more likely to adopt in years with high densities of females with large pouch young. Adoption did not improve juvenile survival. We conclude that adoptions in this wild population were potentially costly and likely caused by misdirected care, suggesting that eastern grey kangaroos may have poorly developed mother-offspring recognition mechanisms.
动物中的收养行为很罕见，通常归因于亲缘选择。在一项对东部灰袋鼠（大赤袋鼠）为期6年的研究中，326只幼崽中有11只被收养。我们通过观察有标记的母亲和幼崽之间的行为关联及哺乳行为发现了8起收养事件，另外通过使用微卫星DNA分析母亲和幼崽的亲缘关系又发现了3起。4起收养涉及相互交换，3起是母亲自己育儿袋中的幼崽后来失踪的情况。收养母亲与彼此或被收养者没有密切的亲缘关系，但通过半体重指数衡量，收养母亲和幼崽之间的关联程度与亲生母子对一样紧密。交换幼崽的母亲之间没有密切关联。母亲的年龄和身体状况不影响收养的可能性，但在育儿袋中有大幼崽的雌性密度较高的年份，雌性更有可能收养。收养并没有提高幼崽的存活率。我们得出结论，这个野生种群中的收养行为可能代价高昂，且可能是由错误导向的照料导致的，这表明东部灰袋鼠的母婴识别机制可能发育不完善。
