Successfully breeding two individual organisms at a zoo and obtaining fertile offspring for several generations is no guarantee that the same could occur in nature (i. e., in the wild). Which species concept becomes difficult to confirm because of this fact?
a. biological
b. ecological
c. morphological
d. phylogenetic
e. paleontological

Explanation:

According to biological species concept, a species is a group of organisms that can potentially interbreed or mate with one another to produce viable fertile offspring

In some cases, organisms of different species can mate and produce healthy offspring, but the offspring are infertile, can’t reproduce

For example, when a female horse and a male donkey mate, they produce hybrid offspring called mules

The biological species concept connects the idea of a species to the process of evolution because members of a species can interbreed, the species as a whole has a common gene pool, a collection of gene variants