Do avian cooperative breeders live longer?

Abstract

Cooperative breeding is not common in birds but intriguingly overrepresented in several families, suggesting that predisposing factors, similar ecological constraints or a combination of the two facilitate the evolution of this breeding strategy. The life-history hypothesis proposes that cooperative breeding is facilitated by high annual survival, which increases the local population and leads to a shortage of breeding opportunities. Clutch size in cooperative breeders is also expected to be smaller. An earlier comparative analysis in a small sample of birds supported the hypothesis but this conclusion has been controversial. Here, I extend the analysis to a larger, worldwide sample and take into account potential confounding factors that may affect estimates of a slow pace of life and clutch size. In a sample of 81 species pairs consisting of closely related cooperative and non-cooperative breeders, I did not find an association between maximum longevity and cooperative breeding, controlling for diet, body mass and sampling effort. However, in a smaller sample of 37 pairs, adult annual survival was indeed higher in the cooperative breeders, controlling for body mass. There was no association between clutch size and cooperative breeding in a sample of 93 pairs. The results support the facilitating effect of high annual survival on the evolution of cooperative breeding in birds but the effect on clutch size remains elusive.

Eusociality but not fossoriality drives longevity in small mammals

“…While previous studies have not shown an association between cooperative breeding and maximum longevity in mammals [9] and birds [10], these results suggest that eusociality in mammals, as defined by Williams and Shattuck, is strongly associated with increased lifespans.…”

Sex, long life and the evolutionary transition to cooperative breeding in birds

“…Theoretical evidence to date therefore suggests that long life increases the likelihood of cooperation evolving. Consistent with this prediction, comparative analyses have demonstrated that cooperative breeders are longer lived than non-cooperative breeders [11,13,14]. This finding, however, is also consistent with the alternative prediction that long life evolves as a result of cooperative breeding: group living protects individuals from extrinsic causes of mortality, which thus selects for longer life [15,16].…”

“…Conversely, high promiscuity is more likely to undermine the evolution of cooperation in short-lived species because the indirect fitness benefits of helping are relatively low and the costs of forgoing direct reproduction are relatively high. Building on previous work showing an association between longevity and cooperative breeding in birds [11,13,14], we are now able to distinguish between whether long life is a cause or a consequence of cooperative breeding. We found that long life makes cooperation more likely to evolve by comparing the life spans of the ancestors of cooperative and non-cooperative species, consistent with theoretical models of the evolution of rspb.royalsocietypublishing.org Proc.…”

“…Our different measures of survival were highly correlated (electronic supplementary material, figure S1a -c). We used annual survival in our analyses as these estimates are typically based on wild populations with the largest sample sizes, and as such are less susceptible to outliers than estimates of maximum and average survival [14]. In total, we compiled survival and promiscuity estimates for 238 species of bird (cooperative n species ¼ 35, noncooperative n species ¼ 203; electronic supplementary material, table S2).…”

Evolution of delayed dispersal and subsequent emergence of helping, with implications for cooperative breeding

“…Consequently, recent research has looked more deeply into the specific life-history features that might promote cooperative breeding (Arnold and Owens, 1998;Beauchamp, 2014). Efforts there have centred on finding evidence, among cooperatively breeding species, for the predominance of similar "Kselected" life-history traits.…”