Mutation and speciation Mutation in a single fly gene affects environmental adaptation, leading to
reproductive isolation By Cathy Holding
The path from single mutation to reproductive isolation in speciation may not be immediately
obvious, but a technique reported by Anthony Greenberg and coworkers at the University of Chicago in
the December 5 Science enables direct visualization of the effect of an alteration in a gene in an
otherwise unaltered genetic background. It depends on precise integration of a specific gene into
the correct genomic locus, and in this way, the role of a gene mutation in differential adaptation
can be precisely observed (Science, 302:1754-1757, December 5, 2003).
Greenberg et al. examined the effect of an inactivating mutation in the Drosophila melanogaster gene
desaturase 2, which has a role in pheromone production and hence mating in the fruit fly. In a
genomic background of the inactive gene, ds2M, the authors introduced an active form of the gene
ds2z precisely into the location of the endogenous gene, by recombination using FLP-FRT technology.
They examined cuticular hydrocarbon profiles-the basis of pheromone chemistry-in the active and
inactive lines and observed that the active profile was not recapitulated despite integration of
active ds2, suggesting involvement of other, previously unrecognized gene systems. The authors also
studied the role of the desaturase in cold tolerance and observed that active ds2 decreased cold
tolerance and increased starvation tolerance when used to replace the inactive gene.
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Posted by Robert Karl Stonjek.