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2004
LSU-HHMI Summer Undergraduate Research Program |
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 Kirsten
M. Brown, and Mohamed A. F. Noor, Biological Sciences
A test of the chromosomal rearrangement model in Drosophila
pseudoobscura
Recent studies suggest that chromosomal rearrangements play
a significant role in speciation by preventing recombination
and maintaining species persistence despite interspecies gene
flow. Factors conferring adaptation or reproductive isolation
are maintained in rearranged regions in the face of hybridization,
while such factors are eliminated from collinear regions. As
a direct test of this rearrangement model, we evaluated the
genetic basis of hybrid male sterility in a sympatric species
pair, Drosophila pseudoobscura pseudoobscura and D.
persimilis, and an allopatric species pair, D. pseudoobscura
bogotana and D. persimilis. Our results are consistent
with the proposed model: virtually all of the sterility factors
in the former pair are associated with three inverted regions,
while sterility factors are present in the collinear regions
in the latter pair. These findings indicate recombination and
selection may have eliminated sterility factors outside the
inverted regions between D. p. pseudoobscura and D. persimilis,
suggesting chromosomal rearrangements may facilitate species
persistence despite hybridization.
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