Recombination-rate variation, local adaptation and speciation under gene flow: a unifying theory

Chromosomal recombination is fundamental to local adaptation and speciation, but its role is yet to be understood.

Initial progress of speciation under gene flow may be facilitated by supressed recombination that protects initial weak barriers from swamping by migration or from stochastic loss, but complete speciation may require many physically unlinked barriers.

Here I suggest that genomic architecture underlain by more or less extensive recombination-rate variation may be a key predictive determinant of the progress of speciation.

To test this, I will employ a realistic, model of speciation with gene flow, incorporating recombination-rate variation (with or without chromosomal inversions), and allowing individual genome regions to compete for the accumulation of reproductive barriers.

I will test model predictions against empirical data from three species: one without known inversions (a monkeyflower, Mimulus aurantiacus) and two species with inversions that seem critical for divergence, i.e. a marine snail, Littorina saxatilis, and Atlantic cod, Gadus morhua.

With this, the project will deliver both urgently needed new knowledge regarding the role of recombination-rate variation in local adaptation and speciation, and new tools for analysing and interpreting empirical data.

Above all, the project may change how scientists perceive the role of recombination-rate variation - towards assigning to it the role of a predictive determinant of speciation.