Biology Reference
In-Depth Information
predatory fish were introduced. Guppies from stream areas with high ver-
sus low predation regimes show differences in many characteristics,
including coloration, behavior, life history pattern, and response to pred-
ators (see, e.g., Magurran et al. 1992). Experimental manipulation of the
predation regime for guppies showed that shifts in various life history pat-
terns could be induced in 30-60 generations, corresponding to about 11
yr (Reznick et al. 1999).
In one of the most interesting sets of experiments, O'Steen et al.
(2002) examined the escape behavior in guppies from field populations
that differed naturally in presence or absence of predatory fish, as well as
populations that were created in 1976 and 1981 by introduction of gup-
pies or their predators to new stream areas. For example, in the ArimaVal-
ley of northern Trinidad, the pike cichlid (
Crenicichla alta
), a major guppy
predator, was introduced to a stream section from which it had been
absent. Guppies were also introduced from stream sections with pike
cichlids to areas without this predator. In 1996 and 1997, 26-36 genera-
tions after these introductions, tests of survival of guppies from low and
high predation stream areas were conducted in artificial ponds containing
pike cichlids. In each case, guppies from areas of low predation showed
significantly lower survival than those from high predation areas (table
14.1). Guppies transplanted from areas without pike cichlids to areas with
this predator had gained in survival ability. Guppies transplanted from
Table 14.1.
Survival of guppies from populations of natural high and low predation
regimes and from populations of high and low predation intensity created by trans-
planting guppies or their pike cichlid predator. Survival is the mean number of indi-
viduals surviving out of six individuals per test group. (Data from O'Steen et al.
2002.)
S
OURCE POPULATIONS
M
EAN NUMBER OF SURVIVORS
High
Low
High
Low
predation source
predation source
predation survivors
predation survivors Significance level
Aripo Valley
Aripo Valley
5.0 +/- 0.8
1.1 +/- 0.6
0.0001
(natural)
(natural)
Aripo Valley
Aripo Valley
3.5 +/- 1.4
2.3 +/- 1.0
0.005
(introduced)
(natural)
Aripo Valley
Aripo Valley
4.3 +/- 1.3
2.0 +/- 0.9
0.0006
(natural)
(introduced)
El Cedro Valley
El Cedro Valley
4.1 +/- 1.3
2.4 +/- 1.2
0.003
(natural)
(introduced)
