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D 0.391 differ (P> SE =
<0.001), but slopes did not ÷ 0.315L, 0.05) In0.012; and Mat’s
pike: D 6.880 + 0.374L, SE = 0.066. Regres
sIons were significantly different between treat
ments in both ponds (analysis of SCIENCE • P VOL. 258 • 20 NOVEMBER 1992
<0.001), but slopes did not differ (P> 0.05) In
SCIENCE 258 1349 Body depth (mm) Body d Effects Of Predators On Prey Populations
Do Predators Reduce Prey Populations Below Carrying
- Predators can control prey populations.
- More likely to occur when predators exhibit:
1. High reproductive capacity.
2. Strong dispersal powers.
3. Ability to switch to alternative food resources.
***If the organism has these three characteristics, in general, you are more likely to be able to keep a prey population
quite below its carrying capacity*** Ex. Cyclamen mites (Tarsonemus pallidus) and predatory
KEY Cyclamen mite (prey)
Typhiodrornus (predator) 40
0 .9 60 p - p - I Figure 18.3 Predators can control prey
populations. Infestation of strawberry plots
by cyclamen mites (Tarsonemus pallidus) in
the presence of the predatory mite
Typhiodromus (above) and in its absence
(below). Prey populations are expressed as
numbers of mites per leaf; predator levels are
the numbers of leaflets out of 36 on which
one or more Typhiodromus were found.
Parathion treatments are indicated by “p.”
After C. B. Huffaker and C. E. Kennett, Hilgardia
26:191 —222 (1956). Photo of Typhiodromus
courtesy of 1PM Program, Cornell University. 0. 40 20. M —1k A SON
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