Using seasonal genomic changes to understand historical adaptation to new environments: Parallel selection on stickleback in highly?variable estuaries

Parallel evolution is considered strong evidence for natural selection. However, few studies have investigated the process of parallel selection as it plays out in real time. The common approach to study historical signatures populations already well adapted different environments. Here, document under conditions, we six threespine stickleback (Gasterosteus aculeatus) inhabiting bar-built estuaries that undergo seasonal cycles environmental changes. Estuaries are periodically isolated from ocean due sandbar formation during dry summer months, with concurrent shifts resemble long-term changes associated postglacial colonization freshwater habitats by marine populations. We used pooled whole-genome sequencing track allele frequency these and search found consistent across estuaries, suggesting a potential role Functional enrichment among candidate genes included transmembrane ion transport calcium binding, which important osmoregulation balance. genomic occur could provide glimpse into early stages adaptation occurred many transitions.