Imagine a scenario in which a common population of animals is separated into two groups by a natural event. Over time, you might expect the two populations to become genetically similar. This process is known as speciation.

less genetically similar; Allopatric speciation

Explanation:

Allopatric speciation is a form of speciation in which a biological population of a species becomes isolated or divided by geographical features, thereby preventing gene flow between the divided subpopulations, which evolve differently into different new species. As a result of the forces of natural selection and genetic drift, the isolated subpopulations evolve into new species that are less genetically similar.

what are the options

it is a limiting nutrient limited by a single nutrient in the ecosystem, & the single goes very slow.