Direct benefits and evolutionary transitions to complex societies

Abstract

The selective forces that drive the evolution of cooperation have been intensely debated. Evolutionary transitions to cooperative breeding, a complex form of cooperation, have been hypothesized to be linked to low degrees of promiscuity, which increases intragroup relatedness and the indirect (that is, kin selected) benefits of helping. However, ecological factors also promote cooperative breeding, and may be more important than relatedness in some contexts. Identifying the key evolutionary drivers of cooperative breeding therefore requires an integrated assessment of these hypotheses. Here we show, using a phylogenetic framework that explicitly evaluates mating behaviours and ecological factors, that evolutionary transitions to cooperative breeding in cichlid fishes were not associated with social monogamy. Instead, group living, biparental care and diet type directly favoured the evolution of cooperative breeding. Our results suggest that cichlid fishes exhibit an alternative path to the evolution of complex societies compared to other previously studied vertebrates, and these transitions are driven primarily by direct fitness benefits.

Evolutionary transitions to cooperative societies in fishes revisited

“…The problems identified in this case study are not unique and we urge caution in the interpretation of results from comparative phylogenetic studies in general. We do agree with Dey et al () though that the lamprologine cichlids of Lake Tanganyika may constitute a fundamental test case for the theory of social evolution, but better information on their behaviour and phylogenetic relationships is needed to allow meaningful analyses.…”

“…A column with the heading “M” was incorrectly treated as signifying “monogamy,” when in fact this category represented the reverse, namely “multi‐male or multi‐female groups: lives in polygynous, polyandrous and/or polygynynandrous groups” Heg and Bachar (), p. 278, table legend). We reanalyzed the Dey et al () dataset based on the original topology of Dey et al, , utilizing the mating pattern classification as graded in the original literature sources (Table ). This new analysis reveals that the mating system does in fact significantly explain the evolutionary transition to cooperative breeding (Figure ), which is in sharp contrast to the inference of Dey et al ().…”

“…The validity of such comparative approaches depends strongly on the quality of information regarding the behaviour, sociality, and reproduction of animals in natural systems, and on the quality of the phylogenetic reconstruction. Applying a novel comparative approach, a recent study of Dey et al (, Nature Ecology & Evolution, 1, 137) concluded that evolutionary transitions to cooperative breeding in cichlid fishes were not associated with the social mating pattern. Here we argue that this result was adversely affected by equivocal classifications of mating patterns, and inadequate phylogenetic data.…”

Heritabilities, social environment effects and genetic correlations of social behaviours in a cooperatively breeding vertebrate

“…Comparing N. pulcher 's genetic architecture of social behaviours to those of other closely related cichlid species that differ in their degree of sociality and cooperative breeding might shed light on the evolution of sociality within this lineage. For instance, the Lamprologini tribe of Lake Tanganyika cichlids comprises around one hundred species which range from nonsocial to highly social and represent a system in which cooperative breeding has evolved repeatedly (Dey et al., ; Heg & Bachar, ; Taborsky, ; Tanaka et al., ). Furthermore, comparisons of genetic correlations between social behaviours in other cooperatively breeding animals, for instance meerkats (Huchard et al., ), red squirrels (Taylor et al., ), yellow‐bellied marmots (Petelle et al., ) but also cooperatively breeding birds (Hunter, ; Komdeur, ) and insects (Leadbeater et al., ; Queller et al., ), could also reveal whether general patterns in cooperative breeders exist, which would contribute to better understand how cooperative breeding evolves.…”

Isotocin neuronal phenotypes differ among social systems in cichlid fishes

“…Therefore, we used a recent tree for the lamprologines [16] that estimates the phylogenetic relationships for 69 species of lamprologine cichlids based on three mitochondrial and six nuclear nucleotide sequences, using a Bayesian Markov chain Monte Carlo model. For the purposes of the current study, the consensus tree from Dey et al .…”