研究报告称：性别有助于抛弃不良遗传负担
NEW YORK, Oct 18 (Reuters Health) - New research may help explain why, despite the advantages of asexual reproduction, so many species follow the example of the birds and the bees.
According to California researchers, sex seems to make it easier to pass on beneficial genetic changes by letting species leave their genetic "baggage" behind.
In an interview with Reuters Health, Dr. William R. Rice of the University of California, Santa Barbara, said that when he looks out his window, nearly everything he sees reproduces sexually. Why this is the case has baffled scientists, Rice noted, since in a comparison of the advantages and disadvantages of sexual versus asexual reproduction, "asexuals always win."
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One advantage of asexual species is that they can increase their population more rapidly than sexual species, Rice explained, since they can clone themselves. And he pointed out that since asexual species do not undergo a process called recombination--a shuffling of the genetic deck that occurs in sexual reproduction--an asexual organism passes down 100% of its genes to its offspring. This allows beneficial combinations of genes to pass unchanged from generation to generation, Rice stated.
, 百拇医药
"It's been an enigma," Rice said, that despite the advantages of asexual reproduction, sex has prevailed in the world.
Rice explained that one possible explanation for why sex so often comes out the winner is that the mixing of genes may make natural selection more efficient. To test this idea, Rice and a colleague, Dr. Adam K. Chippindale, tracked a beneficial genetic mutation in 34 groups of fruit flies.
Half of the flies reproduced with recombination and the other half without it. The researchers tracked the passing down of the beneficial mutation over the course of 10 generations.
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"We found a very strong advantage to recombination," Rice said.
At first, the mutation was passed down from generation to generation at a similar rate in both types of flies, Rice noted. But in later generations, the beneficial mutation increased in the recombining flies, but not in the nonrecombining ones, according to the researcher.
"Recombined populations are going to be better off in the long run, but not in the short run," Rice said.
, 百拇医药
The findings appear in the October 19th issue of the journal Science.
According to Rice, recombination not only allows sexual species to accumulate beneficial genes, or "good stuff," faster, but also to get rid of "bad stuff" faster.
"Sex promotes adaptation by allowing beneficial mutations to spread without being held back by the baggage of deleterious mutations in other genes," according to Richard E. Lenski of Michigan State University in East Lansing.
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In an accompanying editorial, Lenski notes that there are probably additional advantages of sexual reproduction that keep species from turning asexual.
"Evolutionary geneticists will continue to be very interested in sex," he concludes.
SOURCE: Science 2001;294:555-559.
Exception:java.sql.SQLException: Closed Statement, http://www.100md.com
According to California researchers, sex seems to make it easier to pass on beneficial genetic changes by letting species leave their genetic "baggage" behind.
In an interview with Reuters Health, Dr. William R. Rice of the University of California, Santa Barbara, said that when he looks out his window, nearly everything he sees reproduces sexually. Why this is the case has baffled scientists, Rice noted, since in a comparison of the advantages and disadvantages of sexual versus asexual reproduction, "asexuals always win."
, http://www.100md.com
One advantage of asexual species is that they can increase their population more rapidly than sexual species, Rice explained, since they can clone themselves. And he pointed out that since asexual species do not undergo a process called recombination--a shuffling of the genetic deck that occurs in sexual reproduction--an asexual organism passes down 100% of its genes to its offspring. This allows beneficial combinations of genes to pass unchanged from generation to generation, Rice stated.
, 百拇医药
"It's been an enigma," Rice said, that despite the advantages of asexual reproduction, sex has prevailed in the world.
Rice explained that one possible explanation for why sex so often comes out the winner is that the mixing of genes may make natural selection more efficient. To test this idea, Rice and a colleague, Dr. Adam K. Chippindale, tracked a beneficial genetic mutation in 34 groups of fruit flies.
Half of the flies reproduced with recombination and the other half without it. The researchers tracked the passing down of the beneficial mutation over the course of 10 generations.
, http://www.100md.com
"We found a very strong advantage to recombination," Rice said.
At first, the mutation was passed down from generation to generation at a similar rate in both types of flies, Rice noted. But in later generations, the beneficial mutation increased in the recombining flies, but not in the nonrecombining ones, according to the researcher.
"Recombined populations are going to be better off in the long run, but not in the short run," Rice said.
, 百拇医药
The findings appear in the October 19th issue of the journal Science.
According to Rice, recombination not only allows sexual species to accumulate beneficial genes, or "good stuff," faster, but also to get rid of "bad stuff" faster.
"Sex promotes adaptation by allowing beneficial mutations to spread without being held back by the baggage of deleterious mutations in other genes," according to Richard E. Lenski of Michigan State University in East Lansing.
, http://www.100md.com
In an accompanying editorial, Lenski notes that there are probably additional advantages of sexual reproduction that keep species from turning asexual.
"Evolutionary geneticists will continue to be very interested in sex," he concludes.
SOURCE: Science 2001;294:555-559.
Exception:java.sql.SQLException: Closed Statement, http://www.100md.com