Refer to the paragraph about the formation of the isthmus of panama. the sister populations on opposite sides of the isthmus are true species under which species concept?

The answer is reproductive isolation. Reproductive isolation ensures members of different species do not produce offspring. In this case, geographical separation is ensuring that individuals from the two different populations are not able to mate with each other. Eventually, through different selective pressures, the two populations will diverge sufficiently in genotype to become distinctly different.