Ian A. Boussy
Ph.D., 1982, Univ. of California-Davis
Molecular evolution; genetics; Drosophila; transposable elements
I am interested in two aspects of molecular evolution: transposable elements and their effects, and the genetics of speciation.
Transposable elements (TEs) are among the most exciting discoveries of modern genetics. TEs are sequences of DNA that can move from site to site in the DNA of an organism. They can cause mutations when they move, and their movements can be replicative, so that they spread infectively in a sexual population. I study various TEs in the laboratory fruit fly, Drosophila melanogaster. The P element can cause a variety of drastic effects when it is mobilized. It seems to have only invaded D. melanogaster about 50 years ago, and since then it has spread worldwide. I have been monitoring its dynamics in populations in Australia. I have also been studying the genomic dynamics of the P elements, and the traits that they induce in their fly hosts.
Another TE, hobo, may also be a recent invader of D. melanogaster, but hobo seems to have invaded at least twice. Relicts of the earlier invasion can be found in the D. melanogaster genome as mutated sequences, less than 90% identical to hobo.
A fundamental problem in evolutionary studies is to understand the nature of species. Are species distinct because of a few "speciation" genes, or because of an accumulation of differences that add up to a species barrier? Can selection in different habitats lead to speciation? Can sexual selection lead to speciation? One approach to these questions is to identify the genes that contribute to species barriers. This is a tractable problem in Drosophila melanogaster and its sibling species. In collaboration with Chung-I Wu at the University of Chicago, I am attempting to identify the genes that maintain species barriers in this group. I am also studying the genetics of an adaptation of an island endemic, D. sechellia, to a fruit, Morinda citrifolia, that is poisonous to other Drosophila. Selection for morinda tolerance may have led to the speciation between D. sechellia and D. simulans.
Boussy, I.A., & M. Itoh. 2004. Wanderings of hobo: a transposon in Drosophila melanogaster and D. simulans. Genetica 120(1-3): 125-136.
Capy, P., P. Gibert & I.A. Boussy, eds. 2004. Drosophila melanogaster, Drosophila simulans: so similar, so different. Kluwer, Leiden. 292 pp.
Itoh, M., & I.A. Boussy. 2002. Full-size P and KP elements predominate in wild Drosophila melanogaster. Genes & Genetic Systems 77:259-267.
Itoh M., R. Woodruff, M. Leone, IA Boussy, 2000. Genomic P elements and P-M characteristics of eastern Australian populations of Drosophila melanogaster. Genetica 106:231-245.
Boussy, I.A., M. Itoh, D. Rand and R.C. Woodruff. 1998. Origin and decay of the P element-associated latitudinal cline in Australian Drosophila melanogaster. Genetica 104:45-57.
Simmons, G.M., D. Plummer, A. Simon, I.A. Boussy, J. Frantsve and M. Itoh. 1998. Horizontal and vertical transmission of hobo-related sequences between Drosophila melanogaster and Drosophila simulans. ch 21, pp 285-294, in Syvanen, M., ed. Horizontal Gene Transfer. Chapman and Hall, New York. 474 pp.
Boussy, I.A. 1995. A Transposable Element in Natural Populations. Chapter 24 (pp 353-371) in Levine, L., ed. Genetics of Natural Populations: The Continuing Importance of Theodosius Dobzhansky. Columbia University Press, New York. 399 pp.
Periquet, G., F. Lemeunier, Y. Bigot, M.H. Hamelin, C. Bazin, V. Ladeveze, J. Eeken, M.I. Galindo, L. Pascual & I. Boussy. 1994. The evolutionary genetics of the hobo transposable element in the Drosophila melanogaster complex. Genetica 93:79-90.
Fig. P elements in wild D. melanogaster genomes are mostly either full-size P elements or specific deletion-derivatives called KP elements. The ratio of KP to full-size P elements correlates with the P element-associated properties of the flies, and varies dramatically with latitude in eastern Australia.