New phylogenetic information suggests both an increase and at least one loss of cooperative breeding during the evolutionary history of Aphelocoma jays

Abstract

Efforts to identify ecological and life history factors associated with cooperative breeding have been largely unsuccessful, and interest is growing in the role of phylogenetic history in determining the distribution of this social system among lineages. In birds, cooperative breeding is distributed non-randomly among lineages, suggesting that phylogenetic inertia may play an important role in determining its distribution. The bird genus Aphelocoma has been particularly well studied because, although it is a relatively small genus, it shows broad among-lineage variation in level of cooperation. Previous analyses described an unusual unidirectional pattern of evolutionary loss of cooperation in Aphelocoma. Here, historical reconstructions based on new phylogenetic data suggest that evolutionary changes in cooperation have been bidirectional, with at least one gain and at least one loss over relatively recent timescales. This result emphasizes that, although history plays an important role in determining the incidence of cooperative breeding, cooperative behavior can switch relatively quickly in evolutionary time and may be influenced by the ecological context within which particular populations are distributed.

Evolutionary routes to non-kin cooperative breeding in birds

“…Although it is difficult to test this hypothesis directly, recent phylogenetic analyses have revealed several examples of complex social groups with low genetic relatedness that have evolved from lineages with a phylogenetic history of cooperation in smaller, kin-based groups [60] (electronic supplementary material, table S2). For example, the crows and jays (Corvidae) are a large clade in which family cohesiondelayed dispersal of offspring and the formation of stable family groups-appears to be an ancestral behaviour.…”

Islands within an island: Repeated adaptive divergence in a single population

“…Here we test for microgeographic divergence in bill morphology in a New World jay (genus Aphelocoma ). This clade of birds has served as a model system for the study of evolutionary diversification because there are a wealth of examples documenting intra‐ and interspecific variation in ecological niche space (Rice et al ; McCormack et al ), social and breeding systems (Woolfenden and Fitzpatrick ; Berg et al ), and morphological traits (Pitelka ; Peterson ; McCormack and Smith ). Morphological changes have also occurred in association with transitions between habitat types.…”

Social behavior mediates the use of social and personal information in wild jays

“…As the common ancestor of species in the Aphelocoma genus was likely social, it is possible that cognitive abilities like social learning were not lost when CASJ lost sociality 66 – 69 . In fact, species in the Aphelocoma genus notably exhibit wide variation in social behavior, indicating that it is a fairly plastic trait 70 .…”

“…In fact, species in the Aphelocoma genus notably exhibit wide variation in social behavior, indicating that it is a fairly plastic trait 70 . The most supported phylogenetic tree indicates the common ancestor of Aphelocoma species was likely a singular cooperative breeder 68 , 69 with a breeding system similar to that of the extant Florida scrub-jay ( A. coerulescens ) where young delay dispersal to help their parents raise siblings in subsequent breeding attempts. Research on juvenile Florida scrub-jays revealed they possess the ability to socially learn from parents about foraging opportunities in a novel patch 71 .…”