Molecular phylogenetic relationships of Xiphidiopicus percussus, Melanerpes, and Sphyrapicus (Aves: Picidae) based on cytochrome b sequence

Tapping the woodpecker tree for evolutionary insight

Molecular phylogenetic studies of woodpeckers (Picidae) have generally focused on relationships within specific clades or have sampled sparsely across the family. We compared DNA sequences of six loci from 203 of the 217 recognized species of woodpeckers to construct a comprehensive tree of intrafamilial relationships. We recovered many known, but also numerous unknown, relationships among clades and species. We found, for example, that the three picine tribes are related as follows (Picini, (Campephilini, Melanerpini)) and that the genus Dinopium is paraphyletic. We used the tree to analyze rates of diversification and biogeographic patterns within the family. Diversification rate increased on two occasions during woodpecker history. We also tested diversification rates between temperate and tropical species but found no significant difference. Biogeographic analysis supported an Old World origin of the family and identified at least six independent cases of New World-Old World sister relationships. In light of the tree, we discuss how convergence, mimicry, and potential cases of hybridization have complicated woodpecker taxonomy.

An Update of Wallace’s Zoogeographic Regions of the World

Modern attempts to produce biogeographic maps focus on the distribution of species, and the maps are typically drawn without phylogenetic considerations. Here, we generate a global map of zoogeographic regions by combining data on the distributions and phylogenetic relationships of 21,037 species of amphibians, birds, and mammals. We identify 20 distinct zoogeographic regions, which are grouped into 11 larger realms. We document the lack of support for several regions previously defined based on distributional data and show that spatial turnover in the phylogenetic composition of vertebrate assemblages is higher in the Southern than in the Northern Hemisphere. We further show that the integration of phylogenetic information provides valuable insight on historical relationships among regions, permitting the identification of evolutionarily unique regions of the world.

Mitochondrial DNA based phylogeny of the woodpecker genera Colaptes and Piculus, and implications for the history of woodpecker diversification in South America

The woodpecker genus Colaptes (flickers) has its highest diversity in South America and the closely related genus Piculus is restricted to South and Central America. Two species of flickers occur in North America, and one species is endemic to Cuba. We conducted a Bayesian phylogenetic analysis of three mitochondrial encoded genes (cyt b, COI, 12S rRNA) and confirmed that the two genera are paraphyletic. Three species historically classified as Piculus are actually flickers. We found that the Cuban endemic C. fernandinae is the most basal species within the flickers and that the Northern Flicker is the next most basal species within the Colaptes lineage. The South American clade is most derived. The age of the South American diversification is estimated to be 3.6MY, which is synchronous with the emergence of the Isthmus of Panama. The pattern of diversification of South American flickers is common among South American woodpeckers. Although woodpeckers have their greatest diversity in South America, we hypothesize that woodpeckers (Family Picidae) originated in Eurasia, dispersed to North America via the Bering land bridge, and multiple lineages entered South America as the Isthmus approached its final closing.

The role of geography and ecology in shaping the phylogeography of the speckled hummingbird (Adelomyia melanogenys) in Ecuador

The Andes of South America contain one of the richest avifaunas in the world, but little is known about how this diversity arises and is maintained. Variation in mitochondrial DNA and morphology within the speckled hummingbird (Adelomyia melanogenys) was used to elucidate the phylogeographic pattern along an Ecuadorian elevational gradient, from the coastal cordillera to the inland Andean montane region. We examined sequence, climatic/remote sensing and morphological data to understand the effects of topography and ecology on patterns of variation. Populations on either side of the Andes are genetically divergent and were separated during a period that corresponds to the final stages of Andean uplift during the Pliocene. Despite isolation, these two populations were found to be morphologically similar suggesting a strong effect of stabilizing selection across ecologically similar Andean cloud forests, as assessed using climatic and remote sensing data. In contrast, little genetic divergence was found between coastal and west-Andean individuals, suggesting recent interruption of gene flow between these localities. However, coastal populations were found to inhabit different habitats compared to Andean populations as shown by climatic and remote sensing variables. Furthermore, coastal individuals had significantly longer bills compared to their montane relatives, indicative of differential directional selection and the influence of habitat differences in shaping phenotypic variation. Results highlight the role of both isolation and ecology in diversification in Ecuadorian montane regions, while suggesting the two may not always act in concert to produce divergence in adaptive traits.