Understanding the genetic mechanisms of adaptive population divergence is one of
the most fundamental endeavours in evolutionary biology and is becoming increasingly
important as it will allow predictions about how organisms will respond to
global environmental crisis. This is particularly important for the honey bee, a species
of unquestionable ecological and economical importance that has been exposed to
increasing human-mediated selection pressures. Here, we conducted a single nucleotide
polymorphism (SNP)-based genome scan in honey bees collected across an environmental
gradient in Iberia and used four FST-based outlier tests to identify genomic
regions exhibiting signatures of selection. Additionally, we analysed associations
between genetic and environmental data for the identification of factors that might be
correlated or act as selective pressures. With these approaches, 4.4% (17 of 383) of outlier
loci were cross-validated by four FST-based methods, and 8.9% (34 of 383) were
cross-validated by at least three methods. Of the 34 outliers, 15 were found to be
strongly associated with one or more environmental variables. Further support for
selection, provided by functional genomic information, was particularly compelling for
SNP outliers mapped to different genes putatively involved in the same function such
as vision, xenobiotic detoxification and innate immune response. This study enabled a
more rigorous consideration of selection as the underlying cause of diversity patterns
in Iberian honey bees, representing an important first step towards the identification
of polymorphisms implicated in local adaptation and possibly in response to recent
human-mediated environmental changes.
