∞ generated and posted on 2016.09.05 ∞
Presence of more than one allele at a given locus within a gene pool.
Polymorphism is essentially the state that is the opposite of allele fixation. Contrast also with polyphenism.
Note that it is also possible for a population to display variation in phenotype that does not have an underlying genetic basis, though that is not the point here. Indeed, genetic polymorphism actually can exist even in the absence of phenotypic variation within a population.
A healthy population typically is one that is highly polymorphic since the associated high levels of genetic variation can provide much raw material upon which natural selection can act, particularly in response to environmental change. See also balanced polymorphism.
The achievement of polymorphism can be viewed as an indication of the success of a newly acquired allele within a population since an allele must increase in >frequency from initial extremely low levels (e.g., one copy per gene pool) in order to be detectable as a polymorphism.
See also the concept of SNPs (as discussed in the video below) as well as that restriction fragment length polymorphism, i.e., RFLP, and indeed DNA fingerprinting: