Summary: JOURNAL OF AVIAN BIOLOGY 34: 217223, 2003
Phylogeography of Sula: the role of physical barriers to gene flow
in the diversification of tropical seabirds
Tammy E. Steeves, David J. Anderson, Heather McNally, Michael H. Kim and Vicki L. Friesen
Steeves, T. E., Anderson, D. J., McNally, H., Kim, M. H. and Friesen, V. L. 2003.
Phylogeography of Sula: the role of physical barriers to gene flow in the diversifica-
tion of tropical seabirds. J. Avian Biol. 34: 217223.
We examined mitochondrial cytochrome b sequence variation in masked Sula dacty-
latra, red-footed S. sula, and brown S. leucogaster boobies sampled from islands in
the central and eastern Pacific Ocean and in the Caribbean Sea. Each species showed
a different phylogeographic pattern. Whereas haplotypes in masked and red-footed
boobies were shared across the central and eastern Pacific (i.e., across the Eastern
Pacific Basin), brown booby haplotypes were not shared across the Eastern Pacific
Basin. Although most masked booby haplotypes from the Pacific were distinct from
those in the Caribbean, one haplotype was shared across the Isthmus of Panama.
Red-footed and brown boobies, however, did not share haplotypes across the
Isthmus of Panama. We estimate that divergence of these regional populations
occurred within the last 560,000 years. Thus, the Isthmus of Panama and the Eastern
Pacific Basin (albeit to a lesser degree) appear to have played a role in the
diversification of these species.