Genetic Variation: Processes Impacting Allele Frequencies
Genetic variation refers to the diversity of alleles within a population. Several evolutionary processes influence this variation. Let's examine the impact of each option:
Mutation's Role in Variation
Mutation introduces new genetic material (alleles) into a population. This is the ultimate source of new genetic variation.
Migration's Effect on Variation
Migration, also known as gene flow, occurs when individuals move between populations. This process can introduce new alleles into a recipient population or alter allele frequencies, generally increasing genetic variation.
Recombination's Contribution
Recombination, occurring during meiosis, shuffles existing alleles into new combinations on chromosomes. This creates new genotypes and thus increases genetic variation within the population.
Genetic Drift's Impact on Variation
Genetic drift involves random fluctuations in allele frequencies from one generation to the next, particularly significant in small populations. By chance, some alleles may become more or less common, and alleles can even be lost entirely. Therefore, genetic drift typically leads to a decrease in genetic variation within a population.
Conclusion on Genetic Variation
Among the given options, genetic drift is the process that does NOT typically contribute to an increase in genetic variation; instead, it tends to reduce it.
Important Questions from Genetic drift
- In a diploid population of N individuals, the probability of fixation of a new neutral mutation (assuming no other mutation occurs) is _________.
- Two isolated populations M and N have population sizes of 100 and 1000 individuals, respectively. The starting allele frequencies p and q are 0.5 in both populations. Assuming no selection, which one of the following is expected after 100 generations?
- A few years ago, a very small population of zebrafish became isolated by a newly built dam. As a result, which statement is most likely to be true about this population of zebrafish now?
- Which two of the following processes can result in a decline in heterozygosity in populations?
I) inbreeding; II) genetic drift; III) mutation; IV) random mating All else being equal, among isolated populations comprising of 10, 100, 500 and 1000 individuals, the impact of random genetic drift is LOWEST in the population with _____________ individuals.
