Methods
General Methodology
All experimental guppies were male descendants of wild stock caught in
1997 from a high-predation region of the Guanapo River, Trinidad, West
Indies. A total of 90 observers (30 per treatment) and 180 inspectors (30 pairs
per treatment), were used. Prior to testing, guppies were housed in mixed-sex
groups of approximately 350 in two 151 l holding tanks lined with gravel. The
subjects were all kept on a 12 h Light:12 h Dark photoperiod and the water
temperature was maintained at 23C. Three guppies were removed from the
holding tanks and their standard length was measured (mm). The three guppies
in each trial (one observer and two inspectors) were matched for standard
length to within 1 mm (i.e. <5% of their total body length). All guppies used
were naı
¨ve to predators, however predator-naı¨ve guppies in previous experiments have demonstrated inspection behavior (Dugatkin & Alfieri 1991),
indicating that previous experience with predators is not a prerequisite for
normal inspection behavior.
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