Neotropical bird evolution and 100 years of the enduring ideas of Frank M. Chapman

Abstract

The processes of bird diversification in South America have long been a focus of evolutionary biologists and this paper partly acts as an introduction to a selection of such work published in the Biological Journal of the Linnean Society and collated into a Virtual Issue (http://wileyonlinelibrary.com/bij/neotropical-bird-evolution). At the beginning of the 20th century, Frank M. Chapman, curator of birds at the American Museum of Natural History, conducted a series of expeditions in Colombia and Ecuador to 'discover the geographic origins of South American bird-life'. The expeditions produced almost 30 000 specimens, obtained in a sampling scheme aimed at revealing the geographical and elevational distributions of birds. Chapman proposed a series of ideas about the evolutionary origins of the tropical Andean avifauna. Despite being nearly 100 years old, Chapman's evolutionary hypotheses on the role of the appearance of new environments and geographical barriers on speciation, have an enduring influence. With the development of molecular methods and tools for the study of the mechanisms and timing of speciation events, Chapman's hypotheses have seen a revival in the recent scientific literature. Recent work has provided support for some of Chapman's hypotheses, but has also revealed greatly complex processes of biotic differentiation in the Neotropics. What is remarkable is that with means that today seem precarious, Chapman envisioned evolutionary processes at a continental scale that remain valid, in fields that currently advance at an accelerated rhythm and soon render older ideas obsolete.