Evolution of the New World jays (Corvidae): Phylogeny, biogeography, and ecology

Abstract

The evolutionary relationships among the New World jays are investigated in the context of their systematics, biogeography, and ecology. Molecular phylogenetic analyses of mitochondrial and nuclear genes reconstructed a basic phylogenetic structure in which all New World jay (NWJ) genera form a monophyletic group; Cyanolyca is reconstructed as sister to all other NWJ genera, and the remaining genera divide in two lineages: one of Cyanocorax, Calocitta, and Psilorhinus, and another of Aphelocoma, Cyanocitta, and Gymnorhinus . Phylogenetic analysis of Cyanolyca produced a well supported hypothesis of relationships, and showed that the genus Cyanolyca comprises two major clades: one contains the Mesoamerican “dwarf” jays, and the other consist of two main groups—one containing C. cucullata + C. pulchra, and the other containing the “core” South American species. High levels of genetic differentiation within Cyanolyca contrast with those observed in other Andean montane forest lineages studied to date. With only one exception, diverging lineages (sister species, as well as sister clades) are distributed on either side of potentially effective barriers to gene flow, suggesting the importance of allopatry in the diversification of the group. Phylogenetic analyses of Cyanocorax, Psilorhinus, and Calocitta, indicate monophyly of the group, but paraphyly of the current Cyanocorax. Ingroup taxa divided into two groups: Clade A, consisting of Psilorhinus, Calocitta, Cyanocorax violaceus, C. caeruleus, C. cristatellus, and C. cyanomelas, and Clade B, formed by the remaining Cyanocorax species; however, relationships within these groups are not completely resolved. Based on the phylogenetic results lumping of Calocitta and Psilorhinus into Cyanocorax is recommended. Finally, combination of phylogenetic information and ecological niche modeling analyses revealed ecological patterns between sister taxa, as well as ecological trends in the group. In tree out of five pairs of sister species, a pattern of ecological niche conservatism was recovered; in one of those cases such conservatism is probably associated to an allopatric mode of speciation. The remaining two species show ecological and biographic patterns that may be attributed to complex evolutionary histories. Analysis of ecological distances showed that most species are more similar to species other than their sister species, however, when those distances are analyzed in a phylogenetic context, shared ecological trends emerge among some closely related species. Finally, when species ecological niches and niche dimensions where reconstructed into the phylogeny of the assemblage, evolutionary trends pointing to both, niche conservatism and niche diversification, were recovered.