Re: News: No sex for 40 million years? No problem for 1 organism

John Vreeland wrote:

On Thu, 11 Oct 2007 21:57:50 GMT, John Harshman
<jharshman.diespamdie@xxxxxxxxxxx> opined:


Rich Townsend wrote:


John Harshman wrote:


Ye Old One wrote:



No sex for 40 mln years? No problem for 1 organism
Reuters
By Michael Kahn Reuters - 2 hours 10 minutes ago

http://uk.news.yahoo.com/rtrs/20071011/thl-uk-sex-survival-b2e59e8_1.html

LONDON (Reuters) - One microscopic organism has thrived despite
remaining celibate for tens of millions of years thanks to a neat
evolutionary trick, researchers said.

Asexual reproduction has allowed duplicate gene copies of the
single-celled creatures -- called bdelloid rotifers -- to become
different over time.

Ah, science journalism. Rotifers are not single-celled.

And it should seem obvious that if meiosis never happens, homologous
chromosomes will diverge to produce an effectively haploid genome.
What's the surprise?


What, so that each homologous pair of chromosomes (assuming we started as
diploid) drifts so far apart that they're no longer homologous?

Well, no longer detectably homologous. For an example of this, just look
at your X and Y chromosomes.


True dat. So, where is the news this report? I don't se anything
here that we did not already know. While the originally homologous
chromosome originally functions as a neat tool for doubling the
effective size of the gene pool (sort of) the organism still cannot
get rid of "recessive" evil mutations through recombination. And
eventually, as you say, the chromosomes take on new roles in their own
right and can no longer be considered homologous, thus eliminating
"bigger toolkit."

Organisms don't carry along genes just because they might be useful
one day. If it is redundant now then there is selective pressure to
remove it.


There must be something new or it wouldn't be in Science. But from the
news story I don't know what it is.

.

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