Data from: The great Indian joint families of free-ranging dogs

Cooperative breeding is an excellent example of altruistic cooperation in social groups. Domestic dogs have evolved from cooperatively hunting and breeding ancestors, but have adapted to a facultatively social scavenging lifestyle on streets, and solitary living in human homes. Pets typically breed and reproduce under human supervision, but free-ranging dogs can provide insights into the natural breeding ecology of dogs. We conducted a five year-long field based behavioural study on parental care of free-ranging dogs in India. 23 mother-litter units, belonging to 15 groups were observed, which revealed the presence of widespread allo-parenting by both adult males and females. While all the females were known to be related to the pups receiving care, the relatedness with the males could not be determined. Hence, we coined the term "putative father" for caregiving males. Allomothers provided significantly less care than the mothers, but the putative fathers showed comparable levels of care with the mothers. Mothers invested more effort in nursing and allogrooming, while the putative fathers played and protected more. Our observations provide support for both the "benefit-of-philopatry" and "assured fitness returns" hypotheses. Free-ranging dogs are not cooperative breeders like wolves but are rather communal breeders; their breeding biology bearing interesting similarities with the human joint family system. This breeding strategy is likely to have played an important role in increasing pup survival in a stochastic environment and helping to adapt to living among humans during the domestication of dogs.

合作育幼（cooperative breeding）是社会群体中利他合作行为的典型范例。家犬的祖先曾以合作狩猎与育幼为生，但如今家犬已演化出两种生存模式：在街头以兼性社会性的食腐方式活动，或是在人类家庭中独居。伴侣犬通常在人类监护下进行繁殖，但流浪犬能够为我们揭示犬类自然繁殖生态学的真实特征。我们在印度针对流浪犬的亲代抚育行为开展了一项为期五年的野外行为学研究。本次研究共观测了隶属于15个群体的23个母犬-幼崽群，结果显示成年雌雄个体均存在广泛的异亲抚育（alloparenting）行为。已知所有参与抚育的雌性个体均与幼崽存在亲缘关联，但无法确定雄性抚育者与幼崽的亲缘关系。因此我们将参与抚育的雄性个体命名为‘推定父本（putative father）’。异亲雌性（allomother）提供的抚育投入显著少于亲代母犬，但推定父本的抚育投入水平与亲代母犬相当。亲代母犬在哺乳与互理毛发（allogrooming）上投入更多精力，而推定父本则更多参与幼崽的玩耍互动与保护工作。我们的观测结果同时支持‘居留收益假说（benefit-of-philopatry）’与‘确定性适合度回报假说（assured fitness returns）’两大理论假说。流浪犬并非如狼一般属于合作育幼类群，而是群居育幼类群；其繁殖生物学特征与人类的联合家庭系统存在诸多有趣的相似之处。这种育幼策略可能在提升随机波动环境中幼崽存活率，以及助力家犬在驯化过程中适应与人类共处的生活方面发挥了关键作用。