Chromosomal speciation revisited: rearranging theory with pieces of evidence.

The suggestion that chromosomal rearrangements play a role in speciation resulted from the observation that heterokaryotypes are often infertile. However, the first chromosomal speciation models were unsatisfactory and data available to test them was scarce. Recently, large amounts of data have become available and new theoretical models have been developed explaining how rearrangements facilitate speciation in the face of gene flow. Here, we re-examine theoretical predictions and revisit different sources of data. Although rearrangements are often associated with increased levels of divergence, unequivocal demonstration that their role in suppressing recombination results in speciation is often lacking. Finally, we question some previous predictions and suggest new empirical and theoretical approaches to understanding the relevance of rearrangements in the origin of species.