Question

Which of the following statements about Poeceilopsis occidentalis and Poeceliopsis sonorensis are true?

A) Crosses between the two species exhibit very low clutch sizes, and a peculiar, male-biased sex ratio.

B) Males prefer to mate with their own species, but in a pinch, they will mate with females of the other species too.

C) The two species share a common ancestor, approximately one to two million years ago.

D) B and C

E) All of the above.

Answer 1

Poeceiliopsis occidentalis and Poeceiliopsis sonorensis are closely related, allopatric pair of fishes native to the southwest of America and North Mexico. These fall in the category of endangered species. Separation of these two species is estimated to occur about 1-2 million years ago. These species are generally genetically incompatible. Thus, their males prefer to mate females of their own species, however, they may mate females of the other species, which has been found to result in low clutch size due to genetic incompatibility. Also, the offsprings show higher male to female sex ratio, suggesting bias for male sex

So, the answer is (E) All of the above (A, B,C statements) are true for Poeceiliopsis occidentalis and Poeceiliopsis sonorensis