Michael J. Braun

Curator, Dept. of Systematic Biology

National Museum of Natural History
Smithsonian Institution
Washington, D.C. 20560-0534

braunm@si.edu

Research Interests

I. Hybrid zones and speciation assesses the origin, structure and
maintenance of avian hybrid zones within the conceptual framework of speciation. Because they are rich in genetic variation,such zones offer special opportunities to observe how microevolutionary processes produce patterns of geographic diversification. Two case studies are currently underway on manakins and chickadees. In the manakin case, sexual selection may be driving introgression of colorful male plumage traits across the zone (Parsons et al. 1993). In chickadees, selection against hybrids and tight ecological coupling seem to be structuring the zone.

II. Genetic structure and diversity of avian populations examines variation within and among avian populations in relation to biogeographic history, environmental change and life history parameters. One project has examined the loss of genetic diversity in Whooping Cranes, as this species went through a drastic population bottleneck to become critically endangered. DNA derived from museum skins was used to assess variability in historical populations before the bottleneck. Another project looks at genetic divergence and diversity of a recently discovered population of a highly endangered bird, the Red Siskin (Carduelis cucullata).

III. Molecular Phylogenetics - Three systematic studies are in progress: 1) development of the nuclear oncogene c-myc into a new model system for molecular phylogenetics as well as to gain insight into the radiation of modern birds; 2) systematics of caprimulgiform birds using cytochrome b and c-myc gene sequences to assess relationships and age within this poorly known group. Results to date indicate that the group is very old and diverse; 3) phylogeny of falconform birds. A multi-gene phylogeny is expected to help us understand how this group has adapted in parallel to disparate and demanding lifestyles.

2003 Bronson, C. L., T. C. Grubb, Jr., and M. J. Braun. A test of the endogenous and exogenous selection hypotheses for the maintenance of a narrow avian hybrid zone. Evolution 57:630-637.

2003 Braun, M. J., M. B. Robbins, C. M. Milensky, B. J. O'Shea, B. R. Barber, W. Hinds and W. S. Prince. New birds for Guyana from Mts. Roraima and Ayanganna. Bull. Brit. Orn. Club 123: 24-33.

2003 Bronson, C. L., T. C. Grubb, Jr., G. D. Sattler and M. J. Braun. Mate choice: A possible causal mechanism for a moving hybrid zone. Animal Behaviour 65: 489-500.

2001 Brumfield, R. T., R. W. Jernigan and M. J. Braun. Evolutionary implications of divergent clines in a manakin (Manacus; Aves) hybrid zone. Evolution 55: 2070-2087.

2001McDonald, D. B., R. P. Clay, R. T. Brumfield and M. J. Braun . Sexual selection on plumage and behavior in an avian hybrid zone: experimental tests of male-male interactions. Evolution 55:1443--1451.

2001 Brumfield, R. T. and M. J. Braun. Phylogenetic relationships in bearded manakins (Pipridae:Manacus ) indicate that male plumage color is a misleading taxonomic marker. Condor 103:248-258.

2000 Braun, M. J., D. W. Finch, M. B. Robbins and B. K. Schmidt. A Field Checklist of the Birds of Guyana. Smithsonian Institution, Washington , D.C.

2000 Sattler. G. D. and M. J. Braun. Morphometric variation as an indicator of genetic interactions between Black-capped and Carolina chickadees at their contact zone in the Appalachian Mountains. Auk 117:427-444.

2000 Winker, K., G. R. Graves and M. J. Braun. Population genetic differentiation in a migratory songbird: Limnothlypis swainsonii. J. Avian Biology 31: 319-328 .