Biology Reference
In-Depth Information
son 1985). Speciation is possible if spatial separation due to different host
use results in reduced gene flow, if individuals tend to remain on the host
on which they developed and mate there, or if selection related to per-
formance on the different hosts is able to reinforce genetic mechanisms
of host preference and host-specific mating patterns. Later, in chapter 19,
we shall consider speciation in detail.
Alien Opportunities Versus Alien Challenges
Alien plants constitute underused resources for many native herbivores,
and thus it is not surprising that they become incorporated in the diets of
generalist and even specialist animals. The massive introduction of alien
species to new regions presents not only these sorts of opportunities for
native animals but also presents challenges from alien predators, parasites,
and disease agents. In the next chapter, we shall examine the adaptation
of animals to these alien challenges.
