Data from: Neutral and adaptive genomic signatures of rapid poleward range expansion

Many species are expanding their range polewards and this has been
associated with rapid phenotypic change. Yet, it is unclear to what extent
this reflects rapid genetic adaptation or neutral processes associated
with range expansion, or selection linked to the new thermal conditions
encountered. To disentangle these alternatives, we studied the genomic
signature of range expansion in the damselfly Coenagrion scitulum using
4950 newly developed genomic SNPs and linked this to the rapidly evolved
phenotypic differences between core and (newly established) edge
populations. Most edge populations were genetically clearly differentiated
from the core populations and all were differentiated from each other
indicating independent range expansion events. In addition, evidence for
genetic drift in the edge populations, and strong evidence for adaptive
genetic variation in association with the range expansion was detected. We
identified one SNP under consistent selection in four of the five edge
populations and showed that the allele increasing in frequency is
associated with increased flight performance. This indicates collateral,
non-neutral evolutionary changes in independent edge populations driven by
the range expansion process. We also detected a genomic signature of
adaptation to the newly encountered thermal regimes, reflecting a pattern
of countergradient variation. The latter signature was identified at a
single SNP as well as in a set of covarying SNPs using a polygenic
multilocus approach to detect selection. Overall, this study highlights
how a strategic geographic sampling design and the integration of genomic,
phenotypic and environmental data can identify and disentangle the neutral
and adaptive processes that are simultaneously operating during range
expansions.