Biology Reference
In-Depth Information
most safflower is at present small, the argument that a slight evolutionary
shift in preference might make the entire safflower crop sensitive is diffi-
cult to refute.
Greater consideration must also be given to the potential for geo-
graphic and habitat spread of biocontrol agents once they are introduced.
Not only must the potential for natural dispersal be fully considered, as
indicated by the invasion of Florida by Cactoblastis cactorum , the potential
for distribution by unauthorized sale and exchange of the biocontrol
agent must be taken into account. Sales and exchanges via the Internet
have now become a major but poorly regulated means of dispersal of
organisms (Kay and Hoyle 2001).
Fuller consideration of the potential community effects of biocontrol
species is also needed. Any biological agent that has a strong impact on its
target host is likely to influence other species that are part of the host's
food web.
Finally, although the evolutionary potential of biocontrol species has
been shown in only a few instances, this potential needs greater consid-
eration. At the very least, evaluation of genetic variability related to host
use and the response of laboratory populations to artificial selection for
adaptation to potential nontarget hosts needs to be conducted. Monitor-
ing of the genetic responses of introduced agents that have begun to use
nontarget hosts clearly deserves much increased effort.
Biological Control and Coevolution
Thus, we see that biological control species and the target species with
which they interact are capable of rapid evolution. These evolutionary
adjustments are some of the first stages of the coevolutionary adaptation
of new community members to each other. We have seen that alien
species of all types, both inadvertently and deliberately introduced, begin
to make evolutionary adjustments to the new biotic and abiotic condi-
tions they encounter. In the next chapter, we shall examine longer term
patterns of coevolution and integration of alien species into the biotic
community.
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