Avian tree of life
Funded by the NSF’s Assembling the Tree of Life program, our project collected over 32 kilobases of DNA sequences for each of more than 200 representative species across the diversity of modern birds. Hackett, Kimball, Reddy et al. (2008) reported a well-resolved phylogenetic tree of modern birds with many novel and highly-supported, deep relationships. Our analyses also show extremely short internodes at the base of modern birds, indicative of a rapid radiation. Birds exhibit considerable heterogeneity of evolutionary rates within and across lineages. The complexities of nearly simultaneous divergences combined with varying rates of evolution have contributed to the difficulty associated with resolving the phylogenetic history of birds using either genetic or morphological data. Subsequent studies from other labs have corroborated many of the novel relationships uncovered in our study.
Phylogenetics and Biogeography of songbirds in the Old World tropics
The Old World tropics, including Asia, Africa, and Madagascar, comprise a biogeographic realm with past geological and biotic connections such that groups in each of these areas often have close relatives in neighboring regions. My work in these regions has expanded our knowledge of the species-limits, phylogenetic relationships, and biogeographic patterns of songbirds. Some of this work is funded by NSF.