Data from: Absence of population structure across elevational gradients despite large phenotypic variation in mountain chickadees (Poecile gambeli)

Montane habitats are characterized by predictably rapid heterogeneity
along elevational gradients and are useful for investigating the
consequences of environmental heterogeneity for local adaptation and
population genetic structure. Food-caching mountain chickadees inhabit a
continuous elevation gradient in the Sierra Nevada, and birds living at
harsher, high elevations have better spatial memory ability and exhibit
differences in male song structure and female mate preference compared to
birds inhabiting milder, low elevations. While high elevation birds breed,
on average, two weeks later than low elevation birds, the extent of gene
flow between elevations is unknown. Despite phenotypic variation and
indirect evidence for local adaptation, population genetic analyses based
on 18 073 single nucleotide polymorphisms across three transects of high
and low elevation populations provided no evidence for genetic
differentiation. Analyses based on individual genotypes revealed no
patterns of clustering, pairwise estimates of genetic differentiation
(FST, Nei's D) were very low, and AMOVA revealed no evidence for
genetic variation structured by transect or by low and high elevation
sites within transects. In addition, we found no consistent evidence for
strong parallel allele frequency divergence between low and high elevation
sites within the three transects. Large elevation-related phenotypic
variation may be maintained by strong selection despite gene flow and
future work should focus on the mechanisms underlying such variation.