Within‐ and between‐group dynamics in an obligate cooperative breeder

Abstract

Cooperative behaviour can have profound effects on demography. In many cooperative species, components of fitness (e.g. survival, reproductive success) are diminished in smaller social groups. These effects (termed group‐level component Allee effects) may lead smaller groups to grow relatively slowly or fail to persist (termed group‐level demographic Allee effects). If these group‐level effects were to propagate to the population level, small populations would grow slowly or decline to extinction (termed population‐level demographic Allee effects). However, empirical studies have revealed little evidence of such population‐level effects. Theoretical studies suggest that dispersal behaviour could either cause or prevent the propagation of group‐level Allee effects to the population level. We therefore characterized within‐ and between‐pack dynamics in a population of African wild dogs (Lycaon pictus) to test these contrasting model predictions. Larger wild dog packs produced more pups, and their members experienced higher survival than those in smaller packs. Nevertheless, larger packs grew more slowly than smaller packs, because natal adults dispersed away from them. Most packs either died out in whole‐pack death events or broke up when their founders died, irrespective of pack size. Overall, packs showed negative density dependence rather than group‐level demographic Allee effects. Larger packs produced more, but not larger, dispersal groups and hence generated more, but not larger, new packs. Larger packs thus contributed more than smaller packs to the number of packs in the population, but their large size did not propagate to their daughter packs. This pattern helps to explain the absence of population‐level Allee effects in this species. Dispersal behaviour, itself driven by natural selection on individual reproductive strategies, played a pivotal role in population dynamics, leading to the formation of new packs and limiting the size of established packs. Understanding dispersal processes is likely to be important to understanding the population dynamics of other cooperatively breeding species.

When to stay and when to leave? Proximate causes of dispersal in an endangered social carnivore

“…In contrast to our expectations but consistent with findings from northern Kenya (Woodroffe, O'Neill, et al, 2019), dispersal rate increased with natal group size (except for females in packs with few pups). As suggested by Woodroffe, O'Neill, et al (2019), it thus appears that inbreeding avoidance and acquisition of direct fitness outside the natal pack outweigh potential feeding benefits associated with larger packs.…”

“…In contrast to our expectations but consistent with findings from northern Kenya (Woodroffe, O'Neill, et al, 2019), dispersal rate increased with natal group size (except for females in packs with few pups). As suggested by Woodroffe, O'Neill, et al (2019), it thus appears that inbreeding avoidance and acquisition of direct fitness outside the natal pack outweigh potential feeding benefits associated with larger packs. However, it is not clear whether larger packs have a greater per capita food intake (Creel & Creel, 2002), since McNutt (1996b) suggested that competition for access to food increases with age and successive litters.…”

“…Furthermore, emigration can be influenced by adult sex ratio, for the scarcity of one sex increases mate competition for the more common sex (Greenwood, 1980). Depending on circumstances, high population density can motivate individuals to either emigrate and avoid increased resource competition in the natal area (Fattebert, Balme, Dickerson, Slotow, & Hunter, 2015; Kim, Torres, & Drummond, 2009), or remain philopatric due to Allee effects or conspecific attraction (Roland, Keyghobadi, & Fownes, 2000; Woodroffe, O'Neill, & Rabaiotti, 2019). Finally, at the level of the environment, the decision to emigrate can be influenced by habitat quality (Bates, Sadler, & Fowles, 2006) and availability of resources such as food (Bonte, Lukáč, & Lens, 2008; Fattebert, Perrig, Naef‐Daenzer, & Grüebler, 2019) or space (Bowler & Benton, 2005).…”

A metapopulation model of social group dynamics and disease applied to Yellowstone wolves

“…If Allee effects only manifest themselves strongly during disease outbreaks, then field studies may tend to attribute the cause of group extinction or population decline to the pathogen, rather than its interaction with the Allee effect. This may be the case with recent studies of wild dogs (52).…”

I Am a Compassionate Conservation Welfare Scientist: Considering the Theoretical and Practical Differences Between Compassionate Conservation and Conservation Welfare

“…Nevertheless, collectives of animals also matter because they are required to ensure the welfare of individuals within them. For example, a critical mass of animals or normal social structure may be needed to ensure safety from predators or for breeding success, or to provide sufficient biodiversity to avoid pathological conditions associated with inbreeding, such as unusual disease susceptibility [62][63][64]. Thus, from a Conservation Welfare perspective, collective-level conservation goals can be important because they contribute to protecting the welfare of individual animals.…”