Animal Mutation Rates Reveal Traits That Speed Evolution
upstart writes:
Now, a massive analysis of 68 diverse vertebrate species, from lizards and penguins to humans and whales, has made the first large-scale comparison of the rates at which species mutate - a first step toward understanding how quickly they can evolve. The findings, published in the journal Nature, unearthed surprising insights into how the tempo for mutations can change and what sets that pace.
The paper roughly "doubles the amount of mutation-rate estimates we have," said Michael Lynch, an evolutionary biologist at Arizona State University who was not involved in the study. Now we have a "better idea of the amount of variation within vertebrates."
With this extensive data, biologists can begin to answer questions about which traits most influence mutation rates and the pace of evolution. "There are things that affect the rate of evolution, [but] we don't know all of them," said Patricia Foster, a professor emerita of biology at Indiana University who was not involved in the study. "This is the start."
[...] If they found a mutation in around 50% of an offspring's DNA, they concluded that it was likely a germline mutation - one inherited through either the mother's egg or the father's sperm. Natural selection can act directly on such a mutation. Less frequent mutations were deemed to have happened spontaneously in tissues outside the germline; they were less relevant to evolution because they wouldn't get passed on.
(Surprisingly often, mismatches in the family trios told the researchers that the fathers listed by the zoos were unrelated to the babies. Zoo representatives would often shrug at this news and say there might have been two males in the cage. "Yeah, well, the other one is the winner," Bergeron would joke.)
In the end, the researchers had 151 usable trios, representing species as physically, metabolically and behaviorally diverse as massive killer whales, tiny Siamese fighting fish, Texas banded geckos and humans. They then compared the species' mutation rates with what we know about the behaviors and characteristics called their life history. They also considered a statistical measure for each species called the effective population size, which roughly corresponds to how many individuals are needed to represent the genetic diversity. (For example, although the human population today is 8 billion, scientists usually estimate our effective population size to be around 10,000 or fewer.) Bergeron and her colleagues looked for patterns of associations in the numbers.
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