Textbook Problem

All but one species of large birds native to New Zealand’s tropical forests are now extinct. Numbers of the one surviving species, the kereru (Hemiphaga, novae seelandine), are declining rapidly due to habitat loss, poaching, predation, and interspecies competition that wiped out the other native birds. The keruru is the only remaining dispersal agent for several native tress that produce big seeds and fruits, mainly because it is the only remaining species that can swallow big fruits (left) and expel big seeds whole. One of these trees, the puriri (Vitex lucens), is New Zealand’s most valued hardwood. Explain, in terms of natural selection, what would happen to puriri trees in New Zealand if the kereru becomes extinct.