Natures wonders: whale vision under water (Introduction)

by David Turell , Sunday, February 21, 2016, 05:11 (3196 days ago) @ David Turell

Last entry has the wrong title:-Same content:-How whales evolved to see well underwater. Their rhodopsin is blue-shifted compared to terrestrial animals:-http://phys.org/news/2016-02-evolution-whale-vision.html-"Researchers from the Department of Ecology and Evolutionary Biology at the University of Toronto used a combination of statistical and experimental methods to determine how the gene coding for the visual protein known as rhodopsin has evolved differently in whales and dolphins relative to terrestrial mammals. By using killer whale rhodopsin as an experimental model, their results show that not only is the rhodopsin gene under natural selection pressure in whales, but also that naturally selected mutations in the gene confer greater sensitivity towards blue-shifted underwater light. This makes it one of the first whale evolution studies to directly link selection patterns with a measurable change in function.-***-"Sarah Dungan, PhD candidate and lead author of the paper elaborates: "Rhodopsin is a light-sensitive protein in the rod cells of your eyes that allows you to see even in dark conditions. Whales are particularly relianton rhodopsin because light fades very quickly with depth underwater. But the majority of light in the ocean is also blue, so if you're a deep diver like a sperm whale,having rhodopsin more sensitive in the blue part of the spectrum allows your eyes to make the most useof the scarce light hundreds of meters below the surface. This could mean the difference between catching your prey or going hungry."-"Even in species that hunt closer to the surface, such as the killer whale, rhodopsin sensitivity is blue-shifted compared to close terrestrial relatives like the cow. -The graph:-
http://cdn.phys.org/newman/csz/news/800/2016/56c83ab5b747e.jpg-"Graphs showing the light sensitivity of killer whale, cow, and mutant killer whale rhodopsins. The killer whale is blue-shifted compared to the cow (a terrestrial mammal), and this difference is accounted for by mutations in the gene sequence."-Comment: Did jumping in the water come before the rhodopsin alteration? Of course, whales had to see to eat.