Predation by ants on wasp larva baits was assessed at five latitudes from 43°N to 2°S. Rates of predation were significantly greater in the tropics; that is, a food item was exploited by ants in significantly less time in the tropics than in the temperate zone. It was also found that predation rates were higher in low second-growth vegetation than in forests and higher on the ground than on vegetation, and that these differences were more pronounced in the temperate zone than in the tropics. Rates of predation occurring on buildings were lower than in natural situations at every latitude. The number of ant species taken at the baits increased from 22 at the northernmost locality to 74 at the southernmost. In all localities but the northernmost the forest habitat produced a greater diversity of species than the field habitat. There was a greater degree of microhabitat specificity among ants in the tropics than in the temperate zone. The proportion of forest canopy specialists also increased toward the tropics. Overall predation rate and ant species richness were found to be positively correlated on a latitudinal scale, but this relationship broke down at the level of habitats and microhabitats.

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The use of personal response systems, or clickers, is increasingly common in college classrooms. Although clickers can increase student engagement and discussion, their benefits also can be overstated. A common practice is to ask the class a question, display the responses, allow the students to discuss the question, and then collect the responses a second time. In an introductory biology course, we asked whether showing students the class responses to a question biased their second response. Some sections of the course displayed a bar graph of the student responses and others served as a control group in which discussion occurred without seeing the most common answer chosen by the class. If students saw the bar graph, they were 30% more likely to switch from a less common to the most common response. This trend was more pronounced in true/false questions (38%) than multiple-choice questions (28%). These results suggest that observing the most common response can bias a student's second vote on a question and may be misinterpreted as an increase in performance due to student discussion alone.