A Widespread Chromosomal Inversion Polymorphism Contributes to a Major Life-History Transition, Local Adaptation, and Reproductive Isolation

An interesting new paper over at PLoS Bio today, looking at the role of chromosomal inversions in adaptation and speciation. In this study, the group found a chromosomal inversion polymorphism that is geographically widespread. Replicated crosses between the prezygotically reproductively isolated annual and perennial "ecotypes" of the yellow monkeyflower, Mimulus guttatus, revealed that chromosomal inversion arrangements are associated with patterns divergence across North America. The inversion polymorphism affected flowering time and other morphological traits between four pairs of annual and perennial populations. To determine if the inversion contributes to adaptation and reproductive isolation a reciprocal transplant experiment, where alternative arrangements of the inversion were reciprocally introgressed into the genetic backgrounds of each ecotype, were performed."Our results demonstrate for the first time in nature the contribution of an inversion to adaptation, an annual/perennial life-history shift, and multiple reproductive isolating barriers."