Researchers at the University of Toronto have studied the evolutionary transition of early whale ancestors fromlife ashore
Whales evolved from mammals that hada common ancestor with hippos and were partly aquatic. The scientists studied whale fossils at the molecular level and focused on the protein rhodopsin, which absorbs light and sends a signal that travels through the retina to the brain.
With the help of computer simulationThe researchers examined data on various rhodopsin proteins in living whales and related mammals. The analysis revealed a gene sequence representing rhodopsin found in the common ancestor of all living whales. The researchers expressed the gene in lab-grown cells to "resurrect" the predicted protein and experiment with purified samples.
humpback whale diving underwater
Scientists note striking biochemicaldifferences between the "resurrected" protein compared to its analogue in terrestrial mammals. Early whale rhodopsin was many times more sensitive to blue light penetrating deepest into the ocean. Its biochemical properties also suggested that early whale retinas could respond quickly to changes in light levels.
Early whales eventually evolved intomany species of toothed and baleen whales that exist today. As they evolved, individual species of whales have occupied ecological niches at different sea levels and even in freshwater rivers, the authors say. Through evolutionary adaptation, some have surfaced from early deep levels to hunt closer to the surface, others have specialized to become even more extreme divers.
It's amazing that now we can get suchthe level of understanding the way of life of a long-extinct organism, simply by doing laboratory experiments with a single protein. Resurrecting ancestral proteins is an incredibly powerful way to figure out how ancient organisms evolved that most people don't know about.
Sarah Dungan, researcher and co-author
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