Related Experiment Video
Updated: Jun 10, 2025
04:43
Visualizing Visual Adaptation
Published on: April 24, 2017
8.9K
Parallel Spectral Tuning of a Cone Visual Pigment Provides Evidence for Ancient Deep-Sea Adaptations in Cetaceans
Hai Chi1, Linxia Sun2, Na Li1
1College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China.
Genome Biology and Evolution
|October 13, 2024
Summary
Whale vision evolved from dichromatic to monochromatic, with losses of key visual pigments. Ancestral pigment analysis reveals shifts toward shorter wavelengths, possibly for deep-sea adaptation before further vision loss.
Area of Science:
- Evolutionary biology
- Comparative genomics
- Vision science
Background:
- Many mammals have dichromatic color vision via two cone pigments.
- Early cetaceans lost violet-sensitive pigments, resulting in monochromatic cone vision.
- Subsequent losses of middle/long wavelength-sensitive (M/LWS) pigments led to rod monochromatic vision in many whale lineages.
Purpose of the Study:
- To investigate the phenotypic evolution of whale visual pigments, specifically M/LWS and rhodopsin (RH1).
- To understand the spectral tuning and functional changes in M/LWS pigments across cetacean evolution.
- To explore potential adaptations related to deep-sea environments.
Main Methods:
- Assessed spectral tuning of M/LWS and RH1 pigments from representative cetacean taxa.
- Performed in vitro analysis of M/LWS pigment sensitivity in pygmy right and Baird's beaked whales.
- Utilized ancestral sequence reconstruction to resurrect and functionally measure ancient M/LWS pigments.
Main Results:
- M/LWS coding sequences were intact but non-functional in pygmy right and Baird's beaked whales, indicating loss of cone vision.
- Ancestral M/LWS pigment from baleen whale ancestors showed green sensitivity with a 40 nm shift to shorter wavelengths.
- Sperm whale ancestor's M/LWS pigment, though non-functional, likely underwent a 20-30 nm shift to shorter wavelengths.
Conclusions:
- Whale visual pigment evolution shows parallel shifts of M/LWS sensitivity to shorter wavelengths.
- These spectral shifts may represent adaptations for increased deep-sea activity in ancestral whales.
- Subsequent ecological factors likely contributed to the complete loss of functional M/LWS pigments in some lineages.
Related Concept Videos
01:22Photoreceptors and Visual Pathways
5.8K
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category,...
5.8K
01:24Color Vision
535
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.
535
01:15Depth Perception and Spatial Vision
601
Depth perception is the ability to perceive objects three-dimensionally. It relies on two types of cues: binocular and monocular. Binocular cues depend on the combination of images from both eyes and how the eyes work together. Since the eyes are in slightly different positions, each eye captures a slightly different image. This disparity between images, known as binocular disparity, helps the brain interpret depth. When the brain compares these images, it determines the distance to an object.
601
01:11Channel Rhodopsins
2.5K
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
2.5K