Question

Identify each scenario as an example of allopatric speciation, sympatric speciation, or neither: Suppose that a population of voles becomes divided by a chasm. A new mating ritual evolves and spreads through one of the populations. One thousand years later, when researchers bring voles from both sides of the chasm into the lab, voles from one population do not successfully interbreed with voles from the other population. What kind of speciation occurred in the voles?

1) Allopatric speciation
2) Sympatric speciation
3) Neither

Answer 1

The division of a vole population by a chasm that led to the inability of the two populations to interbreed is an example of allopatric speciation.

Step-by-step explanation:

In the scenario described, the population of voles became geographically isolated from each other by a chasm. Over time, this physical division and differing evolutionary pressures allowed them to evolve genetic and behavioral differences, such as a new mating ritual that is unique to one population. When researchers bring voles from both sides of the chasm into the lab and they do not successfully interbreed, this is a clear indication that the voles went through allopatric speciation. The geographical isolation prevented the free flow of genes between the populations, leading to the development of reproductive isolation and the emergence of two distinct species.

Answer 2

The speciation observed in the voles is an example of (1) allopatric speciation.

Step-by-step explanation:

Allopatric speciation (1)o ccurs when a physical barrier separates a population, leading to the evolution of distinct traits in each isolated group. In this scenario, the chasm serves as a geographical barrier, dividing the vole population into two isolated groups. Over time, a new mating ritual evolves in one of the populations, further contributing to the genetic divergence between the two groups.

The inability of voles from one population to successfully interbreed with voles from the other population, even in a controlled lab setting, is a strong indication of reproductive isolation. This reproductive barrier reinforces the concept of allopatric speciation, as the geographically separated populations have become distinct species due to both the physical barrier and the evolution of unique mating behaviors.

Allopatric speciation involves the gradual accumulation of genetic differences between populations. The chasm acts as a physical barrier preventing gene flow, leading to genetic divergence over the course of a thousand years. The evolution of a new mating ritual within one of the isolated populations further reinforces the reproductive isolation between them. As a result, the observed lack of successful interbreeding in the lab setting supports the conclusion that allopatric speciation has occurred. The combination of geographical separation and the development of distinct reproductive behaviors has driven the formation of two separate vole species.