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SI Entomology Staff
Seán Brady, Curator of Hymenoptera (Ants & Bees)
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Research Interests:
- Phylogenetics, molecular evolution, and systematics of ants and bees
- Social insect evolution and ecology
- Coevolutionary dynamics, especially in fungus-growing ants
- Phylogenetic and molecular evolutionary theory and methodology
My research concentrates on increasing our understanding of the origins,
diversification, and molecular evolution of social insects, especially
ants and bees. I am particularly interested in applying comparative
approaches that incorporate evidence from systematics, ecology, genetics,
and genomics in order to address specific questions in ant and bee
evolution.
Ant evolution. I am currently a co-PI on an NSF-funded
Assembling the Tree of Life grant on ant phylogenetics, in collaboration
with Phil Ward (UC Davis), Brian Fisher (Cal Academy of Sciences),
and Ted Schultz (Smithsonian). The major goals of this grant are
to: (1) generate and implement new molecular and morphological data
appropriate at several levels of evolutionary resolution, from taxon-wide
questions down to species-level analyses; (2) estimate the timescale
of ant evolution by combining molecular phylogenetic data with the
aculeate fossil record; (3) use this evolutionary framework to study
morphological and ecological traits of ants through evolutionary
time; (4) provide up-to-date internet outlets and other educational
resources for other scientists and the general public. We have recently
used our new molecular information to explore the origin and early
diversification of ants (Brady et al. 2006), and we are currently
engaged in several other projects focused on specific ant taxa.
We are also committed to expanding the contingent of genes available
to all interested researchers; toward this goal I am presently identifying
and developing many new genetic loci for ant molecular work at the
Smithsonian’s Laboratories of Analytical Biology (LAB).
I am also working on several projects involving fungus-growing (attine)
ants, in collaboration with Ted Schultz (Smithsonian), Ulrich Mueller
(UT Austin), and Cameron Currie (University of Wisconsin). This work
uses molecular techniques to dissect the coevolutionary interactions
among the four main participants in this complex system: the insect
agriculturalists; the fungus that they exclusively raise and eat for
sustenance; the pathogenic fungus that periodically invades these nests;
and the bacterial symbionts utilized by the ants in order combat these
pathogens.
Other current projects on ant evolution include a collaboration
with John LaPolla (Towson University) in which we are conducting taxonomic
and phylogenetic work on the highly-invasive “crazy ants” (genus Paratrechina)
and their relatives. My earlier work in ant evolution has included
morphological and molecular studies of army ants (Brady 2003; Brady & Ward
2005) and bulldog ants (Ward & Brady 2003). Although I am not
currently engaged in projects on these taxa, I plan in the near future
to continue my studies of these fascinating ant groups.
Bee
evolution. I also have a strong interest in the evolution
of bees, and working with Bryan Danforth (Cornell University) I have completed
several research projects on this topic. We have inferred the broad-scale
evolutionary pattern of bees, with the surprising result that the earliest
bees may have originated in Africa as host-plant specialists (Danforth et al.,
2006). We have also determined that the three separate origins of eusociality
in halictid bees (sweat bees) occurred quite recently, each approximately 20-25
million years ago, and that their roughly simultaneous eusocial origins may
be attributable in part to climatic changes (Brady et al., 2006). Working
with Smithsonian colleagues Molly Rightmyer and Sam Droege, I am currently
conducting molecular barcoding and phylogenetic studies of the parasitic bees Nomada.
Molecular
evolution and genomics. In addition to my work
in social insect evolution, I have an on-going interest in general topics in
molecular evolution and phylogenetics. In the past I have participated in
projects exploring intron evolution in bees (Brady & Danforth, 2004); the
evolution of resistance alleles in house flies (Rinkevich et al. 2006); long-branch
attraction in angiosperms (Sanderson et al., 2000) and ants (Brady et al.,
2006); and computer simulations of accuracy in large phylogenetic data sets
(Bininda-Emonds et al., 2001).
My current interests in molecular evolution and
genomics include: (1) the comparative analysis of genes found in ants and bees
known to have significant functions in the social behavior of honeybees,
in order to study the molecular evolution of these presumably adaptive
genes across a range of taxa; (2) the refinement of molecular dating
methods; (3) the use of more sophisticated modes of analyses to explore
effects of long branch attraction and heterotachy in empirical data
sets, (including ants, in which we have recently argued that LBA may
have a significant impact [Brady et al., 2006]); (4) the development
of methods to analyze complex coevolutionary systems containing more
than two symbionts, as is the case found in fungus-growing ants. My
intent is that these projects not only address specific questions in
social insect evolution, but also contribute to our general knowledge
of molecular evolutionary processes.
Publications (organized by general category):
Ant evolution
Schultz, T. R. and Brady, S. G. 2008 Major evlolutionary transitions in ant agriculture. Proceedings of the National Academy of Sciences, U.S.A. 105:5435-5440. 
Brady, S. G., Schultz, T. R., Fisher, B. L., and Ward, P. S. 2006.
Evaluating alternative hypotheses for the early evolution and diversification
of ants. Proceedings of the National Academy of Sciences, U.S.A. 103:18172-18177.
Brady, S. G. and Ward, P. S. 2005. Morphological phylogeny of army
ants and other dorylomorphs (Hymenoptera: Formicidae). Systematic
Entomology 30:593-618.
Ward, P. S., Brady, S. G., Fisher, B. L.,
and Schultz, T. R. 2005. Assembling the ant “Tree of Life”. Myrmecologische
Nachrichten 7:87-90.
Brady, S. G. 2003. Evolution of the army ant
syndrome: the origin and long-term evolutionary stasis of a complex of
behavioral and reproductive adaptations. Proceedings of the National
Academy of Sciences, U.S.A. 100: 6575-6579.
Ward, P. S. and Brady,
S. G. 2003. Phylogeny and biogeography of the ant subfamily Myrmeciinae
(Hymenoptera: Formicidae). Invertebrate
Systematics 17:361-386.
Brady, S. G., Gadau, J., and Ward, P. S.
2000. Systematics of the ant genus Camponotus (Hymenoptera:
Formicidae): A preliminary analysis using data from the mitochondrial
gene cytochrome oxidase I. Pp. 131-139 in Austin, A. D., Dowton, M.
(eds.) Hymenoptera.
Evolution, biodiversity and biological control. Collingwood,
Victoria: CSIRO Publishing, xi + 468 pp.
Gadau, J., Brady, S. G., and
Ward, P. S. 1999. The systematics, distribution, and ecology of an
endemic California Camponotus quercicola (Hymenoptera:
Formicidae). Annals of the Entomological Society of America 92:
514-522.
Bee evolution
Brady, S. G., Sipes, S., Pearson, A., and Danforth, B. N. 2006.
Recent and simultaneous origins of eusociality in halictid bees. Proceedings
of the Royal Society B 273:1643-1649.
Danforth, B. N., Sipes, S.,
Fang, J., and Brady, S. G. 2006. The history of early bee diversification
based on five genes plus morphology. Proceedings
of the National Academy of Sciences, U.S.A., 103:15118-15123.
Danforth,
B. N., Brady, S. G., Sipes, S. D., and Pearson, A. 2004. Single copy
nuclear genes recover Cretaceous age divergences in bees. Systematic
Biology 53:309-326.
Molecular evolution and phylogenetics
Rinkevich, F. D., Zhang, L., Hamm, R. L., Brady, S. G., Lazzaro, B.
P., and Scott, J. G. 2006. Frequencies of the pyrethroid resistance
alleles of Vssc1 and CYP6D1 in house flies from the
eastern United States. Insect Molecular Biology 15:157-167.
Brady, S. G. and Danforth, B. N. 2004. Recent intron gain in elongation
factor-1a of colletid bees (Hymenoptera: Colletidae). Molecular
Biology and Evolution 21:691-696.
Bininda-Emonds, O. R. P., Brady, S. G., Kim, J., and Sanderson, M.
J. 2001. Scaling of accuracy in extremely large phylogenetic trees. Pacific
Symposium on Biocomputing 6: 547-558. (The first two authors
contributed equally.)
Sanderson, M. J., Wojciechowski, M.F., Hu, J.-M., Sher-Khan, T, and Brady,
S. G. 2000. Error, bias and longbranch attraction in data for two chloroplast
photosystem genes in seed plants. Molecular Biology and Evolution 17:
782-797.
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