Biologists at the University of Rochester have discovered that an old and relatively unpopular theory about how a single species can split in two turns out to be accurate after all, and acting in nature.
The finding, reported in today's issue of Science, reveals that scientists must reassess the process involved in the origin of species. The beginnings of speciation, suggests the paper, can be triggered by genes that change their locations in a genome.
"In the 1930s there was speculation that parts of chromosomes that switch from one location to another might cause a species to split into two different species," says John Paul Masly, lead author of the paper and doctoral student at the University of Rochester. "Showing that it was more than an academic idea was difficult, and required a bit of luck.
Other genetic causes of speciation are clearly documented in nature, and it wasn't until we had the ability to sequence whole genomes that we could even attempt to investigate the question."
Curiously, the hypothesis nearly died twice.
Theodosius Dobzhansky, a well-known evolutionary geneticist, studied fruit flies in the infant days of genetic research in 1930. He mapped out how it might be possible for sections of chromosomes to relocate themselves in a genome. Those mobile sections can cause sterility in inter-species hybrids, which can act as a speciation pressure.
In theory, the idea was sound, but scientists long debated whether it actually happened in nature. Eventually a competing theory involving the gradual accumulation of mutations was shown to occur in nature so often that geneticists largely dismissed the moving-gene hypothesis.
"We knew going into this that it was a risky experiment," says Masly. "But we hoped we could pull it off." Over the span of the six-year project, the prospects of bolstering the controversial evolutionary idea looked increasingly bleak.