I understand that not self-fertilizing is an adaptive benefit for plants (& all living organisms) but I don't have a scenario that shows how the benefit works.
Given a population w/genetic variations some tiny percentage of which are beneficial in the habitat, why is it such a huge boost to survival to mix your genes?
It is precisely because beneficial adaptations are rare? If beneficial mutations were common would self cloning and fertilizing. be more common? #question#biology#evolution
@futurebird
One point I don't see in (a skim of) the replies is that no gene acts in isolation. The "environment" that each allele interacts with includes all the rest of the genome. So even without new mutations (which happen ALL THE TIME, like each of us carries HUNDREDS), each sexual reproduction event creates a new combination of alleles that might be beneficial, even if the individual alleles would not otherwise.
@futurebird the usual explainations I've encountered in my reading are 1: new diseases come along frequently, and having a wide variety of genes in the population increases the odds of enough organisms having adaptations which enable surviving new diseases, and 2: other environmental changes also come along, less frequently, but again having a wide variety of genes in the population increases the odds of enough organisms surviving.
@futurebirdhttps://www.science.org/doi/10.1126/science.1194513 had an interesting study of nightshades. It absolutely benefits the individual to self fertilize, so a mutation that allows this will spread rapidly. But then the species is less able to adapt to environmental change and thus goes extinct more frequently. Nightshades speciate fast enough to maintain a big enough collection of non-self-fertilizing species.
@futurebird I'm just speculating, but could it be that beneficial genes are more likely spread among the population? In that case, one phenotype conferring "too much" benefit would mean losing all the others to competition, eliminating the possibility of a later generation that includes many or all the beneficial traits.
@tuban_muzuru@futurebird as I understand it, it's good for long term hardiness to keep around recessive traits that are not positive adaptations in the current environment, but might be useful to future generations. An example would be the English pepper moth, they had a dominant gene for white wings that camouflaged them against the bark of birch (?) trees but when the industrial revolution happened and the trees were stained black by coal smoke, the recessive black wings came to predominate
@tuban_muzuru@futurebird so you want your recessive genes to kick around without expressing too often. A self fertilizing heterozygous individual is going to express that gene a lot more often and that is not a positive trait
I think part of what makes this more subtile and harder to understand is shifting from looking at "fitness" on an individual level ... to looking at it at the levels both above an below: the survival of individual traits in the genome... but also the survival of the species.
@funkula@tuban_muzuru@futurebird i think you are thinking of https://en.wikipedia.org/wiki/Kettlewell%27s_experiment which is (was?) indeed the literal textbook example when i was in school, but i read since received a lot of criticism, some from creationists, which are certainly to be dismissed, but not all, and i'm not sure now how good this particular example is.
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