Pleistocene glacial cycles are thought to have played a major role in the diversification of temperate and boreal species of North American birds. Given that coalescence times between sister taxa typically range from 0.1 to 2.0 Myr, it has been assumed that diversification occurred as populations were isolated in refugia over long periods of time, probably spanning one to several full glacial cycles. In contrast, the rapid postglacial range expansions and recolonization of northern latitudes following glacial maxima have received less attention as potential promoters of speciation. Here we report a case of extremely rapid diversification in the songbird genus Junco as a result of a single continent-wide range expansion within the last 10 000 years. Molecular data from 264 juncos sampled throughout their range reveal that as the yellow-eyed junco (Junco phaeonotus) of Mesoamerica expanded northward following the last glacial maximum, it speciated into the dark-eyed junco (Junco hyemalis), which subsequently diversified itself into at least five markedly distinct and geographically structured morphotypes in the USA and Canada. Patterns of low genetic structure and diversity in mitochondrial DNA and amplified fragment length polymorphism loci found in dark-eyed juncos relative to Mesoamerican yellow-eyed juncos provide support for the hypothesis of an expansion from the south, followed by rapid diversification in the north. These results underscore the role of postglacial expansions in promoting diversification and speciation through a mechanism that represents an alternative to traditional modes of Pleistocene speciation.
Long-wattled Umbrellabirds Cephalopterus penduliger are restricted to the Chocó Biogeographical Region, an area with exceptional levels of avian diversity and endemism. Due to widespread habitat loss and hunting pressure, the species is considered globally Vulnerable and Endangered within Ecuador. Little is known of the species' basic biology. This paper presents data on the first confirmed nest recorded for the species. The nest was found in June 2002 atop a tree fern Cyathea sp. located in secondary forest near Mindo, north-west Ecuador, at 1,600 m in the subtropical zone of the Andean slope. Data collected during incubation and nestling provisioning suggest that females may be responsible for all parental care. At the nest, the female provided food an average of once per hour, and brought roughly twice as many invertebrate food items as vertebrate or regurgitated food items. A male was never seen at the nest. In addition to presenting data from the nest, we compare Long-wattled Umbrellabirds to congeners and discuss implications for the conservation of this species.
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