Now, research by University of Nebraska-Lincoln biologists has found convergent evolution of a key physiological innovation that traces back through the two deepest branches of the vertebrate family tree.
A team led by Jay Storz (prounounced storts), assistant professor of biological sciences, analyzed the complete genome sequences of multiple vertebrate species and found that jawless fishes (e.g., lampreys and hagfish) and jawed vertebrates (pretty much everything else, including humans) independently invented different mechanisms of blood-oxygen transport to sustain aerobic metabolism.
Specifically, comparative analysis of their gene repertoires revealed that the ancestors of jawed and jawless vertebrates co-opted completely different precursor proteins to serve as oxygen-transport hemoglobins, the respiratory proteins that give blood its red color.
“The oxygen transport hemoglobins that were independently invented by the jawed and jawless vertebrates are functionally quite similar, but there are numerous structural details that belie their independent origins,” Storz said. “These small but telling differences reflect the fact that the proteins evolved their oxygen-transport function from different ancestral starting points.
My goodness. So the globin fold has independently spawned an oxygen transport protein for blood. Good stuff to talk about in the next entry, doncha think?