THEORETICAL COMPARISONS OF INDIVIDUAL SUCCESS BETWEEN PHENOTYPICALLY PURE AND MIXED GENERALIST PREDATOR POPULATIONS
Authored by L PROVENCHER, SE RIECHERT
Date Published: 1995
DOI: 10.1016/0304-3800(95)92851-m
Sponsors:
United States Environmental Protection Agency (EPA)
National Science and Engineering Research Council of Canada (NSERC)
Platforms:
No platforms listed
Model Documentation:
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Abstract
We investigated by individual-based simulations the role of individual
variation in spider predatory foraging strategies on prey captures and
spider fecundity. We created 18 generalist intraspecific spider
phenotypes by crossing 3 levels of aggressiveness with 6 strategies of
prey species selection. These phenotypes were tested in 1 and 4 patches
in a fixed area habitat and with 2 and 5 prey species.
In a first group of simulations, spiders of all phenotypes competed for
prey in a mixed-phenotype and stochastic environment. Prey selection
strategy had a highly significant effect on predator success.
Aggressiveness had no direct effect. Individual variation within
phenotypes was high. Habitat fragmentation caused the decline of prey
numbers and, thus, prey captures and spider fecundity. Increased prey
richness enhanced spider fecundity. The phenotype that achieved the
highest fecundity and captured the most prey exhibited high
aggressiveness while specializing on the prey type which was
statistically predicted to be numerically prominent in the next time
interval. The phenotype that did the least well in the system was not
aggressive and specialized on a randomly chosen prey type per time
interval. In the second set of simulations, we completed separate trial
runs of the `'best'' and `'worst'' phenotypes for spider populations
composed of a single phenotype. Here, the aggressive and statistical
strategy captured less prey and was less fecund than the non-aggressive, random phenotype. Thus, predation results from pure phenotype
populations do not apply to mixed-phenotype ones.
Tags
Prey
Decisions
Game
Manipulation
Patchy environment
Tracking
Agelenopsis-aperta
Biological-control
Habitat selection
Spider misumena-vatia