Are Fungi Closer To Plants Or Animals
Animals and Fungi: Evolutionary Tie?
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April 16, 1993
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They may seem awfully vegetative in their habits, and the academy researchers who study them may often be counted equally members of the botany section, but fungi are turning out to be far more than closely related to animals than to plants, scientists say.
In a new analysis of genetic relationships among organisms with complex cells, including sponges, protozoa, algae, plants and animals, researchers have ended that animals and fungi share a common evolutionary history and that their limb of the genealogical tree branched away from plants perchance 1.1 billion years ago. Fungi and animals then went their ain way some undetermined time after that.
The new findings, which appear today in the journal Science, suggest that the common ancestor of animals and fungi was a and so-chosen protist, a unmarried-celled creature that very probable possessed both animal and fungal characteristics -- peradventure spending role of its early life cycle in a bleary and mobile form resembling a human sperm, and at a different stage growing a stiff cell wall similar to that seen in today's fungi. Evolution Study by Genes
The new report did not await at fossil data or physical traits of organisms, as more traditional taxonomic studies have washed, but rather took the currently popular approach of studying evolution past examining genes. Through analyzing the same genes in many different species and tracking how many mutational changes accept occurred in the genes from one organism to the next, scientists are able to summate kinships based on circuitous mathematical models rather than on an eyeball appraisal of how species wait.
In this case, the reckoning overturned previous evolutionary copse that for whatsoever number of anthropocentric reasons, had placed the kingdoms of fungi and animals very far apart.
The discovery was greeted with enthusiasm by many mycologists, the specialists who study fungi and who long take felt their field has been ignored in favor of brute science. New Condition for Mycology
"I think this is very interesting, and it'south quite gratifying," said Dr. John W. Taylor of the University of California at Berkeley. "Mayhap it's time for us to movement out of the botany section and into the zoology department."
Or better yet, he said, to promote mycology to a status worthy of its own department. Dr. Taylor is a mycologist, but his title is professor of plant biology. And he admits that convincing people that they have anything in common with a mushroom, a bundle of baker's yeast, or a flower of mold on an fetid piece of cheese volition have some doing.
Researchers said, nonetheless, that the evolutionary affinity between animals and fungi could explain why fungal diseases in humans are and then difficult to treat. "A lot of the metabolism is so similar that y'all can't target a fungus sufficiently without gravely affecting the homo host besides," said Dr. Mitchell 50. Sogin of the Middle for Molecular Development at the Marine Biological Laboratory in Forest Hole, Mass., the main writer of the new report.
Fungal diseases are a particularly severe problem in those with suppressed immune systems, including AIDS patients and people who have had organ transplants.
Dr. Sogin also suggested that the new results volition buttress long-standing arguments amid yeast geneticists that fungal cells offering a wonderfully tractable way of looking at essential biological bug of relevance to humans.
"If you're looking for precursors to the nervous arrangement, you might consider looking for them in fungi," he said.
Citing some other case of how fungal cells can yield benefits for man studies, Dr. Gerald Fink, director of the Whitehead Institute for Biomedical Research in Cambridge, Mass., and a yeast geneticist, pointed out that there is a mutation in yeast cells much similar the 1 that gives rise to Lou Gehrig's disease, a fatal neurodegenerative disorder. The new discovery of kinship, he said, "just shows in one case again that yeast is a perfect model for man," adding, "I feel vindicated." Agreement and Discord
Some other report by scientists at Indiana University in Bloomington, at present nether consideration for publication by a major scientific journal, likewise reaches the conclusion that fungi and animals are closely related.
Only molecular geneticists working in the laboratory of the belatedly Allan Wilson of the University of California at Berkeley, who before his death in 1991 was a celebrated proponent of looking at genes for clues to evolution, said their analysis of the molecular data contradicts the latest report. They said their study places animals and plants together in a group, with fungi having branched off from the tree earlier.
"Mitch Sogin'south results aren't significant and he's over-interpreting his information," said Arend Sidow, a graduate student working at Berkeley on molecular evolution. But Mr. Sidow's results have nonetheless to exist published and thus scientists said information technology was impossible to judge the claim of his claim.
In the new study, scientists considered the genes that produce then-chosen ribosomal RNA, a component of the protein-making factories plant in all living cells. They compared the genes from dozens of species of eukaryotes, a group of organisms with circuitous cellular structure that includes everything from yeast to plants to mammals. Many of the eukaryotes the scientists considered were obscure creatures like choanoflagellates, microscopic beings surrounded by tentacle structures, but they did include in their analysis such familiar species equally frogs and jellyfish.
Through comparing changes that occurred in the ribosomal genes, the scientists were able to piece together an evolutionary tree for the vast group of eukaryotic organisms.
Source: https://www.nytimes.com/1993/04/16/us/animals-and-fungi-evolutionary-tie.html
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