title: No apparent benefits of allonursing for recipient offspring and mothers in the cooperatively breeding meerkat.
abstract: Cooperative behaviours by definition are those that provide some benefit to another individual. Allonursing, the nursing of non-descendent young, is often considered a cooperative behaviour and is assumed to provide benefits to recipient offspring in terms of growth and survival, and to their mothers, by enabling them to share the lactation load. However, these proposed benefits are not well understood, in part because maternal and litter traits and other ecological and social variables are not independent of one another, making patterns hard to discern using standard univariate analyses. Here, we investigate the potential benefits of allonursing in the cooperatively breeding Kalahari meerkat, where socially subordinate females allonurse the young of a dominant pair without having young of their own. We use structural equation modelling to allow us to account for the interdependence of maternal traits, litter traits and environmental factors. We find no evidence that allonursing provides benefits to pups or mothers. Pups that received allonursing were not heavier at emergence and did not have a higher survival rate than pups that did not receive allonursing. Mothers whose litters were allonursed were not in better physical condition, did not reconceive faster and did not reduce their own nursing investment compared to mothers who nursed their litters alone. These patterns were not significantly influenced by whether mothers were in relatively good, or poor, condition. We suggest that allonursing may persist in this species because the costs to allonurses may be low. Alternatively, allonursing may confer other, more cryptic, benefits to pups or allonurses, such as immunological or social benefits.
authors: Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, CB2 3EJ, Cambridge, UK.|Behavioural Ecology Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
authors: Kirsty J
authors: KJ
authors: MacLeod
authors: Behavioural Ecology Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.|School of Integrative Biology, University of Illinois, Urbana, IL, 61801, USA.
authors: Katie E
authors: KE
authors: McGhee
authors: Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, CB2 3EJ, Cambridge, UK.|Mammal Research Institute, University of Pretoria, Pretoria, South Africa.
authors: Tim H
authors: TH
authors: Clutton-Brock
mesh_terms: D000818:Animals; D000833:Animals, Suckling; D001522:Behavior, Animal; D003299:Cooperative Behavior; D005260:Female; D008988:Herpestidae / Q000502:physiology*; D007774:Lactation / Q000502:physiology*; D008425:Maternal Behavior; D012919:Social Behavior; D012930:Social Dominance; D013019:South Africa
keywords: Suricata suricatta; allonursing; cooperation; maternal condition; structural equation modelling