Data from: Microevolutionary selection dynamics acting on immune genes of the green veined white butterfly, Pieris napi

Insects rely on their innate immune system to successfully mediate complex
interactions with their microbiota, as well as the microbes present in the
environment. Previous work has shown that components of the canonical
immune gene repertoire evolve rapidly and have evolutionary
characteristics originating from interactions with fast-evolving
microorganisms. Although these interactions are likely to vary among
populations, there is a poor understanding of the microevolutionary
dynamics of immune genes, especially in non-Dipteran insects. Here we use
the full set of canonical insect immune genes to investigate
microevolutionary dynamics acting on these genes between and among
populations by comparing three allopatric populations of the Green Veined
White butterfly, Pieris napi (Lepidoptera, Pieridae). Immune genes showed
increased genetic diversity compared to genes from the rest of the genome
and various functional categories exhibited different types of signatures
of selection, at different evolutionary scales, presenting a complex
pattern of selection dynamics. Signatures of balancing selection were
identified in 10 genes, and 17 genes appear to be under positive
selection. Genes involved with the cellular arm of the immune response as
well as the Toll pathway appear to be enriched among our outlier loci,
regardless of functional category. This suggests that the targets of
selection might focus upon an entire pathway, more than on functional
subsets across pathways. Our microevolutionary results are similar to
previously observed macroevolutionary patterns from diverse taxa,
suggesting that either the immune system is robust to dramatic differences
in life history and microbial communities, or that diverse microbes exert
similar selection pressures.