Search

Predictable trait variation across environments suggests shared adaptive responses via repeated genetic evolution, phenotypic plasticity or both. Matching of trait–environment associations at phylogenetic and individual scales implies consistency between these processes. Alternatively, mismatch implies that evolutionary divergence has changed the rules of trait–environment covariation. Here we tested whether species adaptation alters elevational variation in blood traits. We measured blood for 1217 Andean hummingbirds of 77 species across a 4600‐m elevational gradient. Unexpectedly, elevational variation in haemoglobin concentration ([Hb]) was scale independent, suggesting that physics of gas exchange, rather than species differences, determines responses to changing oxygen pressure. However, mechanisms of [Hb] adjustment did show signals of species adaptation: Species at either low or high elevations adjusted cell size, whereas species at mid‐elevations adjusted cell number. This elevational variation in red blood cell number versus size suggests that genetic adaptation to high altitude has changed how these traits respond to shifts in oxygen availability. [ABSTRACT FROM AUTHOR]

Aim To assess geographical and temporal patterns of diversification in Metallura hummingbirds, particularly with respect to topographical barriers and climatic variation between different populations. Location Tropical Andes. Methods We estimated a multilocus phylogeny for all nine species of Metallura and evaluated phylogeographical patterns within Metallura tyrianthina using mitochondrial DNA sequences from across its range ( n = 192). We tested mechanisms of diversification using climatic classification of sampling sites, coalescent-based dating, lineages-through-time plots and dispersal-vicariance analysis. Results Metallura consists of two main clades: (1) the tree line specialists in the M. aeneocauda superspecies; and (2) a habitat-generalist clade that includes M. tyrianthina and M. iracunda. Metallura phoebe was recovered as sister to the tree line clade in some analyses. In both clades, there was marked genetic structure across topographical barriers and almost no structure between climatically distinct regions in the absence of barriers. The tree line clade exhibited deeper divergences in the Central Andes than elsewhere, and a south-to-north history of diversification, whereas the habitat-generalist clade showed deeper divergences in the Northern Andes and a history of southward expansion. A pure-birth model explained the steady net rate of diversification of Metallura hummingbirds through the Pliocene and the Pleistocene. Main conclusions Isolation across topographical barriers best explained the genetic structure in M. tyrianthina. The two Metallura clades expanded from opposite ends of the Andes, leading to asynchronous divergence across common topographical barriers. Cycles of expansion followed by isolation may explain the preponderance of idiosyncratic area relationships that are typical of Andean clades. Geoclimatic dynamism during the Pleistocene caused Metallura and other Andean bird clades to undergo radical range shifts, including dispersal across topographical barriers, that became key to their diversification. [ABSTRACT FROM AUTHOR]

An important challenge in community ecology is to determine how processes occurring at multiple spatial, temporal, and phylogenetic scales influence the structure of local communities. While indexes of phylogenetic structure, which measure how related species are in a community, provide insight into the processes that shape species coexistence, they fail to pinpoint the phylogenetic scales at which those processes occur. Here, we explore a framework to identify the species and clades responsible for the inferred patterns of phylogenetic structure within a given community. Further, we evaluate how communities that share the nonrandom representation of species from a given clade in the phylogeny are distributed across gepgraphy and environmental gradients. Using Ecuadorian hummingbird communities, we found that multiple patterns of phylogenetic structure often occur within a local assemblage. We also identified four geographic regions where species from certain clades exhibit nonrandom representation: the eastern Amazonian lowlands, the western dry lowlands, the Andes at middle elevations, and the Andes at high elevations. The environmental gradients along which changes in the local coexistence of species occurred were mainly elevation, annual precipitation, and seasonality in both temperature and precipitation. Finally, we show how these patterns can be used to! generate hypotheses about the processes that allow species coexistence. [ABSTRACT FROM AUTHOR]

The article presents a study that investigated a controversial 100-year-old hummingbird specimen, the holotype and the only known specimen of the Bogotá sunangel Heliangelus zusii. The study used mtDNA sequence data to prove that the holotype represents a valid species and to show that H.zusii is genetically well differentiated from taxa which was thought to have given rise to the specimen through hybridization.

How biotic interactions, current and historical environment, and biogeographic barriers determine community structure is a fundamental question in ecology and evolution, especially in diverse tropical regions. To evaluate patterns of local and regional diversity, we quantified the phylogenetic composition of 189 hummingbird communities in Ecuador. We assessed how species and phylogenetic composition changed along environmental gradients and across biogeographic barriers. We show that humid, lowelevation communities are phylogenetically overdispersed (coexistence of distant relatives), a pattern that is consistent with the idea that competition influences the local composition of hummingbirds. At higher elevations communities are phylogenetically clustered (coexistence of close relatives), consistent with the expectation of environmental filtering, which may result from the challenge of sustaining an expensive means of locomotion at high elevations. We found that communities in the lowlands on opposite sides of the Andes tend to be phylogenetically similar despite their large differences in species composition, a pattern implicating the Andes as an important dispersal barrier. In contrast, along the steep environmental gradient between the lowlands and the Andes we found evidence that species turnover is comprised of relatively distantly related species. The integration of local and regional patterns of diversity across environmental gradients and biogeographic barriers provides insight into the potential underlying mechanisms that have shaped community composition and phylogenetic diversity in one of the most species-rich, complex regions of the world. [ABSTRACT FROM AUTHOR]