8.1 Genetic Variation
This blog post is allowing me to dig deep into my current and past knowledge of evolutionary forces. Looking back on what I have learned so far, I can apply some concepts to this question of why genetic variation is not eroded over time due to selection.
Although selection may eliminate genetic variation, we will still see mutations occurs in an organisms genome. Just because selection eliminates some, doesn't mean more won't arise. This can be due to environmental factors, or simply mistakes made during DNA replication. A wide array of things can cause genetic variation, so just because selection "eliminates" the variation, is not to say that it will not continue to occur through these processes.
We can also see that selection is not the only force that acts on genetic variation. Say selection did eliminate variation, we will can still see gene flow and genetic drift occur and introduce variation into individuals and therefore the population. Selection is not always the most influential effect on a population.
Heterozygotes can also influence the genetic variation in a population. They will continue to express and pass down recessive alleles, which allows for genetic variation within a population. A process that could occur from these heterozygote carriers is frequency-dependent selection, allowing one of the alleles to become expressed at higher frequency, then be selected against and the other allele then rises in frequency.
All of these things can allow genetic variation to exist in a population, even if selection is occurring.
Awesome post Allie! I included the aspects of mutations preventing the eradication of genetic variation of a given population in my blog post as well. However, I did not discuss the aspects of gene flow and genetic drift as you are correct that selection may not always be the most influential factor in a given population so I enjoyed how you included this and offered that concrete assertion! Your inclusion of these and other causes that prevent selection from causing a population to become genetically consistent is well explicated so great post!
ReplyDeleteHi Allie! I enjoyed reading your posts and your examples were easy to understand. Sometimes I forget that something as simple as a heterozygote can bring both alleles in and therefore, increase genetic variation. You also added in the bigger topics such as genetic drift and gene flow, which I think are very important in bringing genetic variation. I like how you mentioned that even if selection did work to eliminate genetic diversity, there are lots of other ways in which it can be increased!
ReplyDeleteHi Allie,
ReplyDeleteYes! I also mentioned the heterozygote situation in my blog too! Its crazy how we can't ever eliminate recessive alleles because of heterozygotes, but how it's completely possible to eliminate dominant alleles.