The long term goal of the proposed research is to reveal the evolutionary mechanisms that have given rise to biological species. Speciation is difficult to study, even with pairs of closely related species, because their divergence and isolation from each other limits the degree to which the genetic basis of their divergence can be studied. The proposed work will be on Drosophila pseudoobscura, D. p. bogotana and D. persimilis, three closely related and frequently studied new world species. It is possible to generate fertile hybrids of these species, so one can map and count genes that are responsible for the traits associated with isolation. Three complementary approaches to the study of species differences will be joined in this work. A dense microsattelite map has been developed for these species, and these markers will be use for mapping genes responsible for isolation traits, such as sterility, hybrid inviability, and mater discrimination. (2) At the same time as these studies proceed, the genomic regions that flank the individual microsattelite loci will be the subject of a thorough comparative DNA sequence study of intraspecific and interspecific and interspecific variation. Together these two studies will show which genes are linked to those that contribute to isolation, and it will show the historical pattern of divergence that has occurred for these same regions. Previous research has shown that these species have a history that includes more gene flow for some genomic regions than for others. This means that natural selection, acting against gene flow, has been a critical part of their speciation and divergence. (3) A third study will also be done to measure the amount of introgression, from one species to another, that can occur for each microsatellite locus. These introgression experiments will be done in the laboratory. In contrast to the mapping of isolation traits, the introgression mapping does not rely on investigator identified phenotypes. The introgression mapping will assess the relative fitness of the marked genomic regions, when introgressed into closely related species. Each of these three components draws on similar speciation research done in the past on these three species, though in the proposed work, the mapping will be on a much finer scale with many more markers than has been used previously. The proposed work will also permit entirely novel comparisons of the three types of information which can be brought together to develop a fuller and more integrated picture of how these species came to diverge and the genetic basis of the evolutionary forces that have kept them distinct.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM058060-02
Application #
6019477
Study Section
Special Emphasis Panel (ZRG2-BIOL-1 (01))
Project Start
1998-07-01
Project End
2002-06-30
Budget Start
1999-07-01
Budget End
2000-06-30
Support Year
2
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Rutgers University
Department
Other Basic Sciences
Type
Schools of Arts and Sciences
DUNS #
038633251
City
New Brunswick
State
NJ
Country
United States
Zip Code
08901
Machado, Carlos A; Hey, Jody (2003) The causes of phylogenetic conflict in a classic Drosophila species group. Proc Biol Sci 270:1193-202
Dixon, Sheri M; Coyne, Jerry A; Noor, Mohamed A F (2003) The evolution of conspecific sperm precedence in Drosophila. Mol Ecol 12:1179-84
Noor, Mohamed A F; Kliman, Richard M (2003) Variability on the dot chromosome in the Drosophila simulans clade. Genetica 118:51-8
Espinoza, N R; Noor, M A F (2002) Population genetics of a polyploid: is there hybridization between lineages of Hyla versicolor? J Hered 93:81-5
Reiland, J; Hodge, S; Noor, M A F (2002) Strong founder effect in Drosophila pseudoobscura colonizing New Zealand from North America. J Hered 93:415-20
Machado, Carlos A; Kliman, Richard M; Markert, Jeffrey A et al. (2002) Inferring the history of speciation from multilocus DNA sequence data: the case of Drosophila pseudoobscura and close relatives. Mol Biol Evol 19:472-88
Noor, M A; Cunningham, A L; Larkin, J C (2001) Consequences of recombination rate variation on quantitative trait locus mapping studies. Simulations based on the Drosophila melanogaster genome. Genetics 159:581-8
Noor, M A; Grams, K L; Bertucci, L A et al. (2001) Chromosomal inversions and the reproductive isolation of species. Proc Natl Acad Sci U S A 98:12084-8
Noor, M A; Kliman, R M; Machado, C A (2001) Evolutionary history of microsatellites in the obscura group of Drosophila. Mol Biol Evol 18:551-6
Williams, M A; Blouin, A G; Noor, M A (2001) Courtship songs of Drosophila pseudoobscura and D. persimilis. II. Genetics of species differences. Heredity 86:68-77

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