Tree of life gets a total makeover (Introduction)

by David Turell , Saturday, August 22, 2015, 21:15 (3170 days ago)

Using genetic studies, what seems related isn't and whole new classes are created:-https://www.sciencenews.org/article/tree-life-gets-makeover-"In the new vision — based on increasingly sophisticated genetic analyses — people and other animals are closer cousins to single-celled choanoflagellates than to other multi­cellular organisms. Giant kelp that grow as wavering undersea forests off the California coast are closer relatives to single­-celled plankton called diatoms than to multicelled red seaweeds or plants.-"The old tree isn't exactly wrong. The kingdoms that used to crown its top — plants, fungi and animals — still exist. But they've moved. In the new diagram, the tree's former crowning glories shrink to mere side branches, three among hundreds, crowded by the vast diversity of complex single cells.-"Biologists analyzing this treetop rarely use the word kingdom anymore. They talk of five or maybe seven bigger branches called supergroups. And the story of demoting kingdoms and introducing supergroups is far from over. A 2014 review noted five proposals for designating the most ancient stretch of supergroup branches, the bit that goes lowest on the new tree. A paper appearing in the Proceedings of the National Academy of Sciences in February described a new method for resolving this debate, and discussions continue.-***-"The new arrangement, summarized in 2012 by Sina Adl of the University of Saskatchewan and colleagues in the Journal of Eukaryotic Micro­biology, makes a fabulous mix of convergence and divergence. Animals are close relatives of fungi. Both are opisthokonts, along with some one-celled cousins. A Phytophthora potato pathogen, once famous as the “fungus” that caused famine in Ireland in the 1840s, is not a fungus at all. It belongs in the same supergroup as the giant kelp. Red and green seaweeds join plants in a distinct group called the archaeplastids."-Comment: What has resemblance on the outside may not show genetic relationships.