REPRODUCTIVE ISOLATION AND LOCAL ADAPTATION QUANTIFIED FOR A CHROMOSOME INVERSION IN A MALARIA MOSQUITO
Article first published online: 28 NOV 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 67, Issue 4, pages 946–958, April 2013
How to Cite
Ayala, D., Guerrero, R. F. and Kirkpatrick, M. (2013), REPRODUCTIVE ISOLATION AND LOCAL ADAPTATION QUANTIFIED FOR A CHROMOSOME INVERSION IN A MALARIA MOSQUITO. Evolution, 67: 946–958. doi: 10.1111/j.1558-5646.2012.01836.x
- Issue published online: 3 APR 2013
- Article first published online: 28 NOV 2012
- Accepted manuscript online: 29 OCT 2012 01:41PM EST
- Received January 3, 2012 Accepted October 2, 2012 Data Archived: Dryad doi:10.5061/dryad.k94p3
- assortative mating;
Chromosome inversions have long been thought to be involved in speciation and local adaptation. We have little quantitative information, however, about the effects that inversion polymorphisms have on reproductive isolation and viability. Here we provide the first estimates from any organism for the total amount of reproductive isolation associated with an inversion segregating in natural populations. We sampled chromosomes from 751 mosquitoes of the malaria vector Anopheles funestus along a 1421 km transect in Cameroon that traverses savannah, highland, and rainforest ecological zones. We then developed a series of population genetic models that account for selection, migration, and assortative mating, and fit the models to the data using likelihood. Results from the best-fit models suggest there is strong local adaptation, with relative viabilities of homozygotes ranging from 25% to 130% compared to heterozygotes. Viabilities vary qualitatively between regions: the inversion is underdominant in the savannah, whereas in the highlands it is overdominant. The inversion is also implicated in strong assortative mating. In the savannah, the two homozygote forms show 92% reproductive isolation, suggesting that this one inversion can generate most of the genetic barriers needed for speciation.