Final answer:
The source of genotypic variation within a single organism that can result from environmental factors is somatic mutations. Somatic mutations contribute to genetic diversity within the organism's tissues but do not affect the germ cells and are not passed to offspring. Mutation and sexual reproduction are the two main mechanisms generating genetic diversity in a population.
Step-by-step explanation:
One source of genotypic variation within a single organism, which may be the result of environmental factors, is somatic mutations. These are changes to an organism's DNA that occur after conception and can introduce new genetic variation into an organism. Unlike genetic recombination, gene flow, or genetic drift, somatic mutations do not affect an individual's germ cells and, therefore, cannot be passed on to the next generation, However, they can contribute to genetic diversity within an individual's tissues.
Genetic diversity in a population arises primarily from two mechanisms: mutation and sexual reproduction. Mutation is a permanent change in DNA sequence and is the ultimate source of new genetic variation in any population, potentially leading to the introduction of new alleles and thus phenotypic changes. Sexual reproduction facilitates genetic diversity through the unique combination of alleles from two parents. Moreover, while the process of mutation is random and can introduce new genotypic variations, the process of migration, resulting in gene flow, also generates genetic variation, though not randomly.