RT Journal Article
SR Electronic
T1 The last common ancestor of bilaterian animals possessed at least 7 opsins
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 052902
DO 10.1101/052902
A1 MD Ramirez
A1 AN Pairett
A1 MS Pankey
A1 JM Serb
A1 DI Speiser
A1 AJ Swafford
A1 TH Oakley
YR 2016
UL http://biorxiv.org/content/early/2016/05/13/052902.abstract
AB Opsins, the primary proteins animals use to sense light, have undergone a dramatic expansion since they originated early in animal evolution. Understanding the origins of opsin diversity can offer clues to how separate lineages of animals have repurposed different opsin paralogs for different light-detecting functions. However, the more we look for opsins outside of eyes and from additional animal phyla, the more opsins we uncover, suggesting we still do not know the true extent of opsin diversity, nor the ancestry of opsin diversity in animals. To estimate the number of opsin paralogs present in the last common ancestor of all bilaterians and Cnidaria + Bilateria, we reconstructed a reconciled opsin phylogeny using sequences from 15 animal phyla, including the traditionally poorly-sampled echinoderms and molluscs. Our analysis strongly supports a repertoire of nine opsin paralogs in the bilaterian ancestor and four opsin paralogs in the last common ancestor of cnidarians+bilaterians. Thus we have found a greater opsin diversity earlier in animal history than previously known. Further, opsins likely duplicated and were lost many times, with different lineages of animals maintaining different repertoires of opsin paralogs. This phylogenetic information can inform hypotheses about the functions of different opsin paralogs and be used to understand how and when opsins were incorporated into complex traits like eyes and ex-traocular sensors.