The common edible frog of Europe is a hybrid between two named species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they rarely produce offspring. Which of the following statements is the best inference about the two Rana species?
A) They are different species and postzygotic isolation exists between the two frog species.
B) Prezygotic isolation exists between the two frog species.
C) The two species are likely in the process of fusing back into one species.
D) The hybrids form a separate species under the biological species concept.

Question

Quizplus · Accepted Answer

Prezygotic isolation mechanisms prevent mating or fertilization between species, while postzygotic isolation mechanisms occur after fertilization, often resulting in the production of infertile offspring. The fact that hybrids between Rana lessonae and Rana ridibunda rarely produce offspring when they mate among themselves suggests that postzygotic isolation exists between the two frog species, as their hybrid offspring are likely infertile or have reduced fertility. This supports the idea that they are indeed different species according to the biological species concept, which defines species based on reproductive isolation.

The Common Edible Frog of Europe Is a Hybrid Between