The Common Edible Frog of Europe Is a Hybrid Between

Multiple Choice

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.