Answer:
Gene flow or allele flow is the transfer of genes or genetic variation among populations.
This gene flow or migration of genes help maintain the similarities between the species or genetic diversity in a population but slows the process of speciation and variation in the population.
The causes of gene flow are:
1. Random mating- random mating among organisms of different population causes movement of alleles in populations.
3. Recombination of chromosomes during meiosis- can change the alleles of the organism.
2. Mutation- mutation in DNA can create new alleles in a population.
4. Random fertilization.
