Dissertation Research: Exploring the Temporal & Geographical Origins of Neotropical Diversity: Comparison of 32 Superspecies Groups in the Avian Families Galbulidae and Bucconidae

Louisiana State University, Baton Rouge LA

Investigators

Abstract

A grant has been awarded to Dr. Frederick Sheldon and Mr. Christopher Witt at Louisiana State University to study the evolutionary origins of the exceptionally high species diversity of birds found in the Neotropics. Although biologists have known for centuries that the global distribution of biodiversity is skewed towards the tropics, little is understood about the phylogenetic relationships of tropical organisms and the historical events that may have led to their extensive diversification. This study will use museum collections to make DNA comparisons among every available species and population of two families of Neotropical birds, the puffbirds and jacamars. Trees of evolutionary lineages will be reconstructed using analyses that incorporate models of molecular evolution into measurements of DNA similarity. Patterns of new species formation and genetic differentiation will be compared among related groups that share common distributions. In this way, evolutionary trees will be used to infer the ages of evolutionary lineages and to identify the geological and climatic factors that have contributed to modern day diversity at all taxonomic levels. The results will have implications for the ongoing debate regarding relative contributions of long-term geological stability versus recent climatic tumult to the disparity in diversity between temperate and tropical bird faunas. This study will involve collection of DNA data from many related organisms across a broad geographic region. The results will have two primary benefits: (1) inference of evolutionary causes of species diversification; and (2) identification of conservation priorities. Current classifications almost certainly do not adequately represent true genetic diversity in tropical organisms. Genetic studies such as this one are needed to identify cryptic or overlooked species, to recognize areas that harbor significant genetic diversity, and to suggest strategies for protecting both the products and the process of evolution.