Biology Reference
In-Depth Information
American chestnuts, based on observations in Europe that such strains
tended to displace those of high virulence (see, e.g., Grente and Bertthe-
lay-Sauret 1978).
Altogether, these studies demonstrate that plant species tend to show
genetic variability to most disease agents, even those that have been intro-
duced to new regions. Strong selection for increased resistance appears
likely in most cases and is slowed only by the long generation time of
many species of shrubs and trees.
Adaptation by Plants and by Herbivores
Native plants have considerable potential for evolutionary adaptation to
introduced herbivores and diseases. For grasses, in particular, rapid evolu-
tionary adjustments can be seen, but for longer lived woody plants, this
potential is slow to be realized. As we shall see in the next chapter, adap-
tation by native herbivores to introduced plants is much more dramatic.
