local adaptation

Lee C-R & Mitchell-Olds 2012 Environmental adaptation contributes to gene polymorphism across the Arabidopsis thaliana genome. Mol Biol Evol 29:3721-3728.

• balancing selection among heterogeneous environments maintains genetic variation at ecologically important genes
• these results suggest an important role for environmental factors in shaping genome-wide patterns of polymorphism and indicate another direction of genomic study

• the role of environmental heterogeneity in maintaining gene polymorphism has not been investigated at the whole-genome level
• if the biological function of a gene controls environmental adaptation, the geographic distribution of different alleles may be associated with spatially heterogeneous environmental factors, such as temperature or precipitation
• a gene responsible for differential environmental adaptation may also be more polymorphic
• balancing selection might actively maintain locus-specific polymorphism, making it harder for one allele to fix across the species range