Biology Reference
In-Depth Information
Figure 14.1.
Mean number of red-legged frog (
Rana aurora
) tadpoles from popula-
tions existing with (syntopic) and without (allotopic) bullfrogs (
Rana catesbeiana
)
seeking shelter when exposed versus not exposed to chemical cues of larval bull-
frogs. Each test involved 10 tadpoles. One standard error is indicated by the error
bars (Reprinted with permission from J. M. Kiesecker and A. R. Blaustein. 1997.
Population differences in responses of red-legged frogs (
Rana aurora
) to introduced
bullfrogs.
Ecology
78:1752-1760. © 1997 Ecological Society of America.)
populations without bullfrogs did not (fig. 14.1). Experimental predation
experiments were also conducted in the laboratory and in pens located in
natural waters. In the laboratory, survival of red-legged frog tadpoles over
3 days was 87.7% for individuals from populations with bullfrogs and
64.7% for those from sites without bullfrogs. For tests lasting 8 days in nat-
ural waters, the difference was much greater; 90.7% of tadpoles from pop-
ulations with bullfrogs survived, whereas only 43.5% of those from sites
without bullfrogs survived. Kiesecker and Blaustein (1997) concluded that
the differences shown by red-legged frog tadpoles had at least some genetic
basis, since all of the test animals were obtained as prehatching embryos.
Fish faced with introduced predators show several examples of rapid
evolution of antipredator behavior. Perhaps the most detailed studies of
evolutionary change in response to predation have been carried out with
the guppy (
Poecilia reticulata
) in Trinidad. Although the field situation in
Tr inidad does not really involve introduced species that are alien to the
island, stream areas exist in which guppy populations are exposed to and
protected from various predatory fish.These situations have permitted the
experimental study of evolution in populations of guppies to which
