Why is biological diversity so rich in the tropics? One piece of this puzzle may be found in patterns of bird distributions. In South America, the ranges of many lowland bird species are delimited by rivers and large mountain chains. For example, a birdwatcher on the east bank of the Negro River may observe the White-throated Toucan but, if they crossed to the west bank, they would instead find Cuvier's Toucan. A similar species turnover is noticed when crossing from the lowland rainforests west of the Andes to those east of the Andes. These distribution patterns suggest that the formation of rivers and mountains may have played pivotal roles in isolating populations of birds and driving evolutionary diversification in the tropics. This research will analyze genetic data from 125 tropical bird species to examine how rivers and mountains affected species formation and diversity.
A vital component of this collaborative project is the research training it will provide to scientists in developing countries. With labwork and fieldwork planned in Brazil, Colombia, and Venezuela, scientists from North and South America will be exposed to a diversity of natural environments and techniques. The collaborations will result in increased knowledge of how tropical diversity arises and is maintained, and how habitats should be preserved to maximize diversity.
