Data from: Within- and between-group dynamics in an obligate cooperative breeder

1. 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). 2. 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. 3. Theoretical studies suggest that dispersal behaviour could
either cause or prevent the propagation of group-level Allee effects to
the population level. We therefore characterised within-and between-pack
dynamics in a population of African wild dogs (Lycaon pictus) to test
these contrasting model predictions. 4. 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. 5. 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. 6.
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.