Seven salamanders? Seven populations of salamanders in the genus Ensatina , occu

Question

Seven salamanders?

Seven populations of salamanders in the genus Ensatina, occur throughout the western edge of the United States (see figure below). For years, these populations were considered separate species, because they look different from each other. However, a biologists studying these populations discovered that most of these population interbreed to produce viable and fertile hybrids. The only two populations that cannot interbreed are the ones at the southern edge of the range, referred to as Ensantina klauberi and Ensatina eschscholtzii.  

Use this information and your knowledge of biology to answer the following questions.

Answer True or False and give reasoning.

1. Ensantina klauberi and Ensatina eschscholtzii could be different morphological species.

2. Ensantina klauberi and Ensatina eschscholtzii should be considered different biological species.

3. The genes of Ensatina eschscholtzii should be more similar to the genes of Ensatina xanthoptica than they are to the genes of Ensantina klauberi.

4. If biologists consider Ensantina klauberi and Ensatina eschscholtzii to be different species, they would likely argue that postzygotic isolating mechanisms had reinforced speciation.

5. If the population of Ensantina klauberi and the population of Ensatina eschscholtzii remain in contact, natural selection would likely favor a prezygotic isolating mechanism.

Figure 1. Populations of salamanders with distinct color patterns can interbreed, except where they come into contact at the southern portion of the range. oregonensis picta xanthoptica eschscholtzii platensis oregonensis picta xanthoptica eschscholtzii platensis croce ater klauberi Croceater Kauberi

Explanation / Answer

Species is defined by their inability to interbreed with other species. Therefore, Ensantina klauberi and Ensatina eschscholtzii are considered as two different biological species. Ensantina klauberi and Ensatina eschscholtzii have different body colors and morphology. They can be considered as different morphological species. (Questions 1 and 2 are true).

Ensatina seemed to have evolved by the process of speciation. The two different lineages developed on either side of the central valley. Therefore, the genes of Ensantina eschscholtzii should be more similar to the genes of Ensantina xanthoptica than Ensantina klauberi. (Question 3 is true).

Post zygotic isolating mechanisms are due to genomic incompatibility, hybrid inviability or sterility. In, Ensantina klauberi and Ensatina eschscholtzii post zygotic isolation had reinforced isolation. (Question 4 is true).

Prezygotic isolating mechanism occurs if the species show different temporal, behavioral, ecological and mechanical isolation. If, Ensantina klauberi and Ensatina eschscholtzii remain in contact, natural selection would likely favor a prezygotic isolating mechanism. (Question 5 is true).

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