Data From: Fit and fatty freshwater fish: Contrasting polyunsaturated fatty acid phenotypes between hybridizing stickleback lineages

Long-chain polyunsaturated fatty acids are biologically important lipids
that are unevenly distributed between and throughout environments. This
heterogeneity can affect the evolution of metabolic processes, as
populations adapt to the resource landscape that they encounter. Here, we
compare fatty acid phenotypes of stickleback over two time scales of
evolutionary divergence: between two lineages with different metabolic
capacities for fatty acid synthesis (i.e. different copy number of the
fatty acid desaturase gene; FADS2) that independently colonized European
freshwaters during the Pleistocene and Holocene; and between two ecotypes
within each lineage that have diverged more recently (~150 years) in
different habitats (i.e. lake and stream). We measured fatty acid profiles
of wild-caught and lab-reared fish for each lineage and ecotype
combination after rearing lab fish on a diet deficient in omega-3
long-chain polyunsaturated fatty acids. Since these lineages hybridize in
nature, we also measured profiles of lab-reared hybrids and backcrosses
raised on the same deficient diet. Wild fish showed strong compositional
differences in fatty acids between habitats, lineages, and sexes. Common
garden fish had generally lower polyunsaturated fatty acid levels than
wild fish, and females had lower omega-6:omega-3 than males. Fish from the
lineage with fewer FADS2 copies also had lower levels of docosahexaenoic
acid. Overall, we document divergence in fatty acid phenotypes between
stickleback lineages with different histories of freshwater colonization,
and between ecotypes in the early stages of adaptive population
divergence.