Huang Y, Chain FJJ, Panchal M, Eizaguirre C, Kalbe M, Lenz TL, Samonte IE, Stoll M, Bornberg-Bauer E , Reusch TBH, Milinski M, Feulner PGD
Habitat-specific gene expression in immune tissues between lake and river sticklebacks
Molecular Ecology 25:943-958, 2016

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Abstract

The observation of habitat-specific phenotypes suggests the action of natural selection. The three-spined stickleback (Gasterosteus aculeatus) has repeatedly colonized and adapted to diverse freshwater habitats across the northern hemisphere since the last glaciation, while giving rise to recurring phenotypes associated with specific habitats. Parapatric lake and river populations of sticklebacks harbour distinct parasite communities, a factor proposed to contribute to adaptive differentiation between these ecotypes. However, little is known about the transcriptional response to the distinct parasite pressure between lake and river populations in a natural setting. Here, we sampled wild-caught sticklebacks across four geographical locations from lake and river habitats. We compared gene expression profiles between lake and river populations using 77 whole-transcriptome libraries from two immune-relevant tissues, the head kidney and the spleen. Differential expression analyses revealed 139 genes with habitat-specific expression patterns across the sampled population pairs. Amongst the 139 differentially expressed genes, 8 are annotated with an immune function and 42 have been identified as differentially expressed in previous experimental studies in which fish have been immune challenged. Together these findings reinforce the hypothesis that parasites contribute to adaptive evolution of sticklebacks in lake and river habitats.