Gene Loss

Publication Details

Identifier: JB_HKSCOI

Curator: M. Lopes-Marques

DOI: 10.1371/journal.pgen.1003432

PMID: 23637615

Title:

Rod monochromacy and the coevolution of cetacean retinal opsins.

Abstract:

Cetaceans have a long history of commitment to a fully aquatic lifestyle that extends back to the Eocene. Extant species have evolved a spectacular array of adaptations in conjunction with their deployment into a diverse array of aquatic habitats. Sensory systems are among those that have experienced radical transformations in the evolutionary history of this clade. In the case of vision, previous studies have demonstrated important changes in the genes encoding rod opsin (RH1), short-wavelength sensitive opsin 1 (SWS1), and long-wavelength sensitive opsin (LWS) in selected cetaceans, but have not examined the full complement of opsin genes across the complete range of cetacean families. Here, we report protein-coding sequences for RH1 and both color opsin genes (SWS1, LWS) from representatives of all extant cetacean families. We examine competing hypotheses pertaining to the timing of blue shifts in RH1 relative to SWS1 inactivation in the early history of Cetacea, and we test the hypothesis that some cetaceans are rod monochomats. Molecular evolutionary analyses contradict the "coastal" hypothesis, wherein SWS1 was pseudogenized in the common ancestor of Cetacea, and instead suggest that RH1 was blue-shifted in the common ancestor of Cetacea before SWS1 was independently knocked out in baleen whales (Mysticeti) and in toothed whales (Odontoceti). Further, molecular evidence implies that LWS was inactivated convergently on at least five occasions in Cetacea: (1) Balaenidae (bowhead and right whales), (2) Balaenopteroidea (rorquals plus gray whale), (3) Mesoplodon bidens (Sowerby's beaked whale), (4) Physeter macrocephalus (giant sperm whale), and (5) Kogia breviceps (pygmy sperm whale). All of these cetaceans are known to dive to depths of at least 100 m where the underwater light field is dim and dominated by blue light. The knockout of both SWS1 and LWS in multiple cetacean lineages renders these taxa rod monochromats, a condition previously unknown among mammalian species.

Last update:

30-08-2024

Associated Glosses (34 results)

GlossID	Species	Symbol	Gene Loss Mechanism	Loss Type	Lineage Specific	Citation
GL_XUN1N4	Inia geoffrensis	OPN1SW	LOF (frameshift, premature stop, ss)	Full	No	10.1371/journal.pgen.1003432
GL_YNAK1I	Caperea marginata	OPN1SW	LOF (frameshift, premature stop, ss)	Full	No	10.1371/journal.pgen.1003432
GL_ZET2E5	Balaenoptera acutorostrata	OPN1SW	LOF (frameshift, premature stop, ss)	Full	No	10.1371/journal.pgen.1003432
GL_ZTA5X9	Megaptera novaeangliae	OPN1SW	LOF (frameshift, premature stop, ss)	Full	No	10.1371/journal.pgen.1003432