An examination of species limits in the Aulacorhynchus "prasinus" toucanet complex (Aves: Ramphastidae)

The number of species recognized in Aulacorhynchus toucanets has varied tremendously over the past century. Revisors seem to disagree on whether head and bill coloration are useful indicators of species limits, especially in the A. "prasinus" complex. Using morphometrics, I tested the hypothesis that the major color-based subspecific groups of A. "prasinus" sensu lato are simply "cookie-cutter" (i.e., morphologically nearly identical) toucanets with different head and bill colorations. Univariate and multivariate analyses show that they are not simply morphological replicates of different colors: a complex array of morphometric similarities and dissimilarities occur between the major subspecific groups, and these variations differ between the sexes. Latitude and longitude had a small but significant association with female (but not male) PC1 and PC2. Hybridization and intergradation were also considered using plumage and bill characters as a surrogate to infer gene flow. Hybridization as indicated by phenotype appears to be substantial between A. "p." cyanolaemus and A. "p." atrogularis and nonexistent between other major groups, although from genetic evidence it is likely rare between A. "p." albivitta and A. "p." cyanolaemus. The congruence and complexities of the morphological and color changes occurring among these groups suggest that ecological adaptation (through natural selection) and social selection have co-occurred among these groups and that species limits are involved. Further, hybridization is not evident at key places, despite in many cases (hypothetical) opportunity for gene flow. Consequently, I recommend that this complex be recognized as comprising five biological species: A. wagleri, prasinus, caeruleogularis, albivitta, and atrogularis. Four of these also have valid subspecies within them, and additional work may eventually support elevation of some of these subspecies to full species. Species limits in South America especially need more study.

Evolutionary patterns of diversification in the Andean hummingbird genus Adelomyia

The patterns of genetic diversity and morphological variation are of central importance in understanding the evolutionary process that drive diversification. We use molecular, morphological, and ecological data to explore the influence of geography and ecology in promoting speciation in the widespread Andean hummingbird genus Adelomyia. Six monophyletic clades were recovered which show distributional limits at well-defined geographic barriers. Percentage sequence divergence ranged between 5.8% and 8.2% between phylogroups separated by large (>4000 km) and small (<50 km) distances respectively, suggesting that geographic isolation may be influential at very different scales. We show that morphological traits in independent phylogroups are more related to environmental heterogeneity than to geographic barriers. We provide a molecular reconstruction of relationships within Adelomyia and recommend its use in future comparative studies of historical biogeography and diversification in the Andes.