American Museum of Natural History

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George F. Barrowclough

Associate Curator (Ornithology)

Ph.D., University of Minnesota, 1980 "Genetic Differentiation in the Dendroica Coronata Complex"

RESEARCH

Dr. Barrowclough uses molecular data, theoretical modeling, and computer analysis to try to establish the relationships of the living birds of the world. He also investigates patterns of demography and geographic variation within avian species.

Determining the relationships of the various families and orders of birds has always been difficult, because many of the major divergence events probably took place 50 to 100 million years ago. Several years ago, Dr. Barrowclough and his colleagues began to use slowly evolving nuclear DNA sequences for this purpose. An active part of the research of his lab group involves identifying nuclear genes with useful systematic properties and sequencing them. Phylogenies of owls and gallinaceous birds have recently been developed in this fashion.

Recent advances in population genetics have made it possible for researchers to recover historical information about the growth and movement of populations using DNA sequences. For example, Barrowclough and his colleagues determined that populations of the threatened spotted owl recently expanded their range into the Sierra Nevada mountains of California, although the populations of these owls have been stable over a long period of time in the Pacific Northwest and in the mountains of Arizona and New Mexico. Similar research aimed at reconstructing the history of population growth, fragmentation, and expansion is currently underway in birds such as barred and tawny owls, juncos, and several species of grouse.

Analyses of this kind are of particular interest in the case of threatened and endangered species because they allow investigators to place the current status of a population in historical perspective. For example, Barrowclough and his colleagues recently showed that the population of the California gnatcatcher in southern California only recently arrived following a range expansion from southern Baja California. Consequently, the recognition of the U.S. population of this species as a distinctive subspecies is not warranted.

Recent Significant Publications

Zink, R. M., G. F. Barrowclough, J. L. Atwood, and R. C. Blackwell-Rago. "Genetics, Taxonomy, and Conservation of the Threatened California Gnatcatcher." Conservation Biology 14 (2000): 1394-1405.

Gutierrez, R. J., G. F. Barrowclough, and J. G. Groth. "A Classification of the Grouse (Aves: Tetraoninae) Based on Mitochondrial DNA Sequences." Wildlife Biology 6 (2000): 205-211.

Barrowclough, G. F., and J. G. Groth. "Demographic Inferences from Coalescent Patterns: mtDNA Sequences from a Population of Mexican Spotted Owls." In Proceedings of the 22nd International Ornithology Congress, ed. N. Adams and R. Slotow, 1914-1921. University Natal, Durban, South Africa, 1999.

G.F. Barrowclough, R. J. Gutierrez, and J. G. Groth. "Phylogeography of Spotted Owl (Strix occidentalis) Populations Based on Mitochondrial DNA Sequences: Gene Flow, Genetic Structure, and a Novel Biogeographic Pattern." Evolution 53 (1999): 919-931.

Groth, J. G., and G. F. Barrowclough. "Basal Divergences in Birds and the Phylogenetic Utility of the Nuclear RAG-1 Gene." Molecular Phylogenetics & Evolution 12 (1999): 115-123.

Rockwell, R. F., and G. F. Barrowclough. "Effective Population Size and Lifetime Reproductive Success." Conservation Biology 9 (1995): 1225-1233.

Barrowclough, G. F., and R. F. Rockwell. "Variance of Lifetime Reproductive Success: Estimation Based on Demographic Data." American Naturalist 141 (1993): 281-295.