Genomic regions repeatedly involved in divergence among plant-specialized pea aphid biotypes
Résumé
Understanding the genetic bases of biological diversification is a long-standing
goal in evolutionary biology. Here, we investigate whether replicated
cases of adaptive divergence involve the same genomic regions in the pea
aphid, Acyrthosiphon pisum, a large complex of genetically differentiated biotypes,
each specialized on different species of legumes. A previous study
identified genomic regions putatively involved in host-plant adaptation and/
or reproductive isolation by performing a hierarchical genome scan in three
biotypes. This led to the identification of 11 FST outliers among 390 polymorphic
microsatellite markers. In this study, the outlier status of these 11
loci was assessed in eight biotypes specialized on other host plants. Four of
the 11 previously identified outliers showed greater genetic differentiation
among these additional biotypes than expected under the null hypothesis of
neutral evolution (a < 0.01). Whether these hotspots of genomic divergence
result from adaptive events, intrinsic barriers or reduced recombination is
discussed.