Opsins in onychophora (velvet worms) suggest a single origin and subsequent diversification of visual pigments in arthropods.
Multiple visual pigments, prerequisites for color vision, are found in arthropods, but the evolutionary origin of their diversity remains obscure. In this study, we explore the opsin genes in five distantly related species of Onychophora, using deep transcriptome sequencing and screening approaches. Surprisingly, our data reveal the presence of only one opsin gene (onychopsin) in each onychophoran species, and our behavioral experiments indicate a maximum sensitivity of onychopsin to blue-green light. In our phylogenetic analyses, the onychopsins represent the sister group to the monophyletic clade of visual r-opsins of arthropods. These results concur with phylogenomic support for the sister-group status of the Onychophora and Arthropoda and provide evidence for monochromatic vision in velvet worms and in the last common ancestor of Onychophora and Arthropoda. We conclude that the diversification of visual pigments and color vision evolved in arthropods, along with the evolution of compound eyes-one of the most sophisticated visual systems known.
Animal Evolution and Development, Institute of Biology, University of Leipzig, Leipzig, Germany. lars.hering@uni-leipzig.de
Lars
L
Hering
Miriam J
MJ
Henze
Martin
M
Kohler
Almut
A
Kelber
Christoph
C
Bleidorn
Maren
M
Leschke
Birgit
B
Nickel
Matthias
M
Meyer
Martin
M
Kircher
Paul
P
Sunnucks
Georg
G
Mayer
D000042:Absorption / Q000528:radiation effects; D000818:Animals; D001181:Arthropods / Q000235:genetics* / Q000528:radiation effects; D001522:Behavior, Animal / Q000528:radiation effects; D030562:Databases, Protein; D019143:Evolution, Molecular; D014644:Genetic Variation; D059014:High-Throughput Nucleotide Sequencing; D008027:Light; D016013:Likelihood Functions; D008297:Male; D055355:Opsins / Q000235:genetics*; D018524:Phototropism / Q000235:genetics / Q000528:radiation effects; D010802:Phylogeny; D059467:Transcriptome / Q000235:genetics; D014785:Vision, Ocular / Q000235:genetics / Q000528:radiation effects
D055355:Opsins