How do we differentiate between positive and negative selection. These two terms sound like they are complementary to each other.
positive selection = positive, directional selection
negative selection = purifying selection
This review might help.
http://genomebiology.com/2002/3/5/reviews/1012
Positive selection: also called (Darwinian selection) variants that increase in frequency until they fix in the relevant population. The selective pressure that leads to this fixation is termed positive selection.
Negative selection: Also called purifying selection, it means that selection is purging changes that cause deleterious impacts on the fitness of the host.
Variation and selection depend from the non-spontaneous and spontaneous processes. The hierarchical thermodynamics determines the direction of evolution and aging of living beings. Please see: On the physical - chemical basis of Darwinism https://www.researchgate.net/profile/Georgi_Gladyshev .....
It's all relative. What about the situation in which selection acts on standing variation and an ancestral allele is preferred? We can say it is purifying selection, because the derived allele is being eliminated. We also can say that it is positive selection because the ancestral allele is driven to high frequency and a selective sweep is produced.
which selection have more impact on virus survival either positive or negative?
Hello C. S; Any trait that is associated with reproductive success that exceeds the population average is under POSITIVE selection and that trait will become more common in the population. If the trait is associated with a reproductive rate that is less than the population average it is under NEGATIVE selection and will become less common. That's how natural selection works. Cheers, Jim Des Lauriers
Hello Dao; You can find some papers that deal with your question by going to Google Scholar and asking for "measuring selection pressure". Good luck, Jim Des Lauriers
Hi. I suggest for you the following website that I hope could help you:
https://www.akadeum.com/blog/what-is-the-difference-between-positive-and-negative-cell-separation/
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