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A latitudinal phylogeographic diversity gradient in birds
This study by Smith et al. uses genetic, environmental, and morphological data from hundreds of bird species occurring in the Western Hemisphere to evaluate patterns of within-species diversity. The authors find greater (and longer lasting) intraspecific genetic variation in tropical species than in temperate species, suggesting that biodiversity gradients can arise more rapidly than previously thought and that the processes governing these gradients operate on multiple evolutionary timescales. The image shows a close-up of a Round-tailed Manakin (Ceratopipra chloromeros), which occurs in the tropics of South America and was one of the 210 New World bird species included in the study.
Image Credit: Ben Winger