One group of researchers wondered if the urban heat island effect in Sao Paulo, Brazil. could be affecting leaf-cutter ants (Atta sexdens) in that city. Mike Angilletta and his colleagues set out to determine if urban ants were more heat tolerant than their rural neighbors, and if so. how did that happen?

Part A - Experimental design: Testing a prediction It has been demonstrated that ectotherms (such as insects and reptiles) in warm climates tolerate higher temperatures than ectotherms in cooler climates. Angilletta hypothesized that urban heat islands could lead to similar differences in heat tolerance between urban and rural populations of leaf-cutter ants. He predicted that ants in urban areas would tolerate heat better than ants in nearby rural areas. Select the two best experimental designs for comparing the thermal tolerance of ants in urban areas to ants in nearby rural areas. Measure the heat tolerance of many ants of the same species as a function of the distance they live from a city center. Measure the feeding activity of many ants of the same species from rural and urban areas in the same region. Measure the heat tolerance of one species of ant from an urban area and the heat tolerance of a different species of ant from a rural area. Measure the heat tolerance of many ants of the same species from a city center and from a rural area in the same region. Measure the heat tolerance of 5 ants from an urban area and 5 ants from a rural area. Measure the heat tolerance of many ants of the same species from urban areas in the north and south of the United States.

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