Adaptive evolution of Nearctic deepwater fish vision: Implications for assessing functional variation for conservation

We report evidence for molecular adaptation in vision in two lineages of Nearctic fishes that are deep lake specialists: ciscoes and deepwater sculpin. We found depth-related variation in the dim-light visual pigment rhodopsin that evolved convergently in these two lineages. We also developed and tested a metabarcoding approach that we show is efficient and accurate in recovering the ecological distribution of functionally relevant variation in rhodopsin.