Concept 24.1

Q1: Two bird species in a forest are not known to interbreed. One species feeds and mates in the treetops and the other on the ground. But in captivity, the two species can interbreed and produce viable, fertile offspring. What type of reproductive barrier most likely keeps these species separate? Explain.

A1: Since the birds are known to breed successfully in captivity, the reproductive barrier in nature must be prezygotic. Given the species differences in habitat preference, the reproductive barrier is most likely to be habitat isolation.

Q2: a. Which species concept can be used for both asexual and sexual species?
b. Which can only be applied to sexual species?
c. Which would be most useful for identifying species in the field?

A2: a. All species concepts except the biological species concept can be applied to both asexual and sexual species because they define species on the basis of characteristics other than abitlity to reproduce.
b. The biological species concept can be applied only to extant sexual species.
c. The easiest species concept to apply in the field would be the morphological species concept because it is based only on the appearance of the organism. Additional information about its ecological habits, evolutionary history, and reproduction are not required.