Trait covariation along the elevation gradient indicated that adaptation to altitude results from the assembly of multiple co-adapted traits into a complex syndrome: as elevation increases, plants flower earlier, produce less tillers, display lower stomata density and carry larger, longer and heavier grains. Our results revealed that phenotypic differentiation at 10 out of the 18 traits was driven by local selection. In parallel, we genotyped these plants for 38 microsatellite markers as well as for 171 outlier single nucleotide polymorphisms (SNPs) that displayed excess of allele differentiation between pairs of lowland and highland populations and/or correlation with environmental variables.
We used two common gardens, and phenotyped 18 traits in 1664 plants from 11 populations of annual teosintes. Here we focused on adaptation of teosinte populations along two elevation gradients in Mexico that display continuous environmental changes at a short geographical scale. Genome scans are popular to uncover outlier loci potentially involved in the genetic architecture of local adaptation, however links between outliers and phenotypic variation are rarely addressed. Yet, much has to be discovered on its environmental drivers, the underlying functional traits and their molecular determinants.
In plants, local adaptation across species range is frequent.