🚀 go-pugleaf

Sorry it took me so long to answer this.

In article <2b21077ewnr070@ark.abg.sub.org> ralf@ark.abg.sub.org (Ralf Stephan) writes:

>Now, I have a question:  Is there any significance in this numbers, that is,
>what (dis)advantage could it have to have a low/high number of genetic
>variation? 

Most of the genetic variation in species is probably neutral with respect 
to fitness. Alleles may differ in nucleotide sequence but not have any
effect on the health, fertility or sexual attractiveness of the
organisms carrying them. The levels of variation most likely reflect 
population size, mutation rate and rate of gene flow more than anything
else. (In addition, citing an average for large groups is probably
nearly meaningless.)

Genetic variation with fitness differences is very fleeting because
selection rapidly depletes the existing variation. The "good" allele
increases in frequency in the gene pool at the expense of the "bad"
allele. Soon, only the "good" allele is left -- no variation.

>Does this increase "fitness" for the species?

Species don't have fitness, genotypes within a population do. Species
do not have reproductive success _as a unit_ so they cannot have a
fitness. Thus, selection cannot act on groups to produce traits
that benefit a species or population as a whole. (There are limited
exceptions.)

>Is this the
>reason why e.g. insects are survival artists?

I would guess (i.e. I have no idea, but I'm commenting anyway 8-)
that it has more to do with their ecology.

>Thanks in advance.
>ralf

Chris Colby 	---	 email: colby@bu-bio.bu.edu	---
"'My boy,' he said, 'you are descended from a long line of determined,
resourceful, microscopic tadpoles--champions every one.'"
 	--Kurt Vonnegut from "Galapagos"