Diversification in the Andes: the Atlapetes brush‐finches

Abstract

With nearly 30 species, the Atlapetes brush‐finches are one of the most species‐rich genera in the New World sparrows (Passerellidae). Atlapetes is mainly distributed in highland forests from Mexico to north‐western Argentina, with a few taxa in the foothills (<1000 m). Species diversity is highest in South America, because of high rates of local replacement but few cases of local co‐occurrence, creating a mosaic of forms with different plumage colours. With the purpose of understanding phylogenetic and environmental determinants of trait evolution, we reconstructed a molecular phylogeny based on full ND2 mtDNA sequences, with focus on the core group of Andean Atlapetes species and related outgroups. Phylogenetic relationships revealed that most Andean species are closely related to a geographical neighbour, although these neighbours may often be phenotypically quite different, with yellow‐plumaged species sister to grey‐plumaged taxa. Biogeographic analyses suggest Mesoamerica as the area of origin for Atlapetes, which dispersed through the Panama Isthmus to the eastern Andean slope, then the western Andes and finally the southern Andes. Diversification in the genus was apparently influenced by the glacial cycles that affected the distribution of montane forests in the Neotropics, particularly during the last million years. Phenotypic plumage changes may be associated with ecological conditions, with black dorsum in the wettest areas and a pale dorsum in a group of closely related species in dry environments on the Pacific slope. Local sympatry and ecological segregation presumably does not lead to increased divergence in plumage signals or song.

Contrasting evolutionary histories in Neotropical birds: Divergence across an environmental barrier in South America

“…Lastly, genomic data made clear the existence of geographic structure within P. m. venezuelensis in the Central Andes region, with up to three populations in this area: one from the Yunguilla valley in Ecuador, and one on each side of the mountain range. Deeper sampling is needed to explore this geographic structure in more detail, particularly in the southern area of the subspecies range west of the Andes where it seems to occupy drier environments than in the rest of its distribution, similar to those found at the semi‐arid Yunguilla valley (Hilty, ; Sánchez‐González, Navarro‐Sigüenza, Krabbe, Fjeldså, & García‐Moreno, ).…”

The diversification of neopasiphaeine bees during the Cenozoic (Hymenoptera: Colletidae)

“…The diversification history of South American Neopasiphaeinae involved, in some instances, geographical (abiotic) forces, and the hypothesis of the Andean uplift as a driver of diversification during the Cenozoic figures as an important explanation for some neopasiphaeine genera, and several publications have agreed on this hypothesis (Antonelli & Sanmartin, ; Antonelli, Nylander, Persson, & Sanmartín, ; Ceccarelli et al, ; Sanchez‐Gonzalez, Navarro‐Siguenza, Krabbe, Fjeldså, & Garcia‐Moreno, ). The changes related to the formation of this Cordillera include the break‐up of ancestral ranges into western and eastern subgroups.…”

Rapid expansion and diversification into new niche space by fluvicoline flycatchers

“…The low frequency of speciation events in the Pleistocene suggests that recent uplift in the northern part of the Andes, and the increased amplitude of climatic cycles during the last 0.9 Ma (Hooghiemstra et al 2006), played a minor role on the diversification rates. Probably most fluvicoline flycatchers are too dispersive for very local differentiation of populations, as seen for instance in spinetails (Furnariidae; Derryberry et al 2011) and some finches (Sanchez-Gonzalez et al 2015). An exception is seen in the genus Muscisaxicola, which diversified during the Pleistocene at very high elevations where Pleistocene ice sheets formed effective isolating barriers (Vuilleumier andSimberloff 1980, Chesser 2000).…”