Problem 6 - AP Psychology Premium Prep 2021

Question

The Middle East blind mole rat ( Nannosplalax ehrenbergi) lives in the Upper Galilee Mountains of Israel. Two groups of these mole rats live in the same region, but scientists discovered that there is a \(40 \%\) difference in mitochondrial DNA between these two groups. These rats do not seem to interbreed in the wild. This is an example of (A) allopatric speciation (B) sympatric speciation (C) pre-zygotic barrier (D) hybrid zone

Step-by-Step Solution

Answer

The correct answer is \( \boxed{\textbf{(C) pre-zygotic barrier}} \). The two groups of Middle East blind mole rats live in the same region but do not interbreed in the wild, indicating a reproductive barrier preventing mating or fertilization between the groups. The significant genetic differences between the groups suggest that they are still the same species but are experiencing a pre-zygotic barrier.

Step 1: 1. Understanding the terms

Allopatric speciation: This is a form of speciation where two populations of a species become geographically isolated from each other, leading to genetic divergence and the development of distinct species. Sympatric speciation: This is the process of speciation where new species evolve without a geographic barrier, often due to ecological, behavioral, or genetic factors. Pre-zygotic barrier: This is a reproductive barrier that prevents mating or fertilization between two different populations or species, reducing the likelihood of gene flow between them. Hybrid zone: This is an area where two distinct species interbreed, producing hybrids with various characteristics from both parental species. Now let us analyze the information about the mole rats and determine which option best describes the situation.

Step 2: 2. Comparing the given information with the options

In the given situation, two groups of Middle East blind mole rats with significant genetic differences coexist in the same region of the Upper Galilee Mountains of Israel. They are not interbreeding in the wild. It indicates a reproductive isolation that prevents gene flow between these two groups.

Step 3: 3. Determining the correct answer

Analyzing the options and the given information, we can rule out: - allopatric speciation (since the mole rats are living in the same region, there is no geographic isolation); - hybrid zone (since they are not interbreeding). Between sympatric speciation and pre-zygotic barrier, the most likely answer is: \( \boxed{\textbf{(C) pre-zygotic barrier}} \) The \(40\%\) difference in mitochondrial DNA between the two groups suggests that they are still the same species, but the fact that they are not interbreeding in the wild indicates that there is a reproductive barrier preventing mating or fertilization between the groups, which is a pre-zygotic barrier.