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Temperature and Hunger Alter Grouping Trade-Offs in Whirligig Beetles
William L. Romey and David S. Rossman
The American Midland Naturalist
Vol. 134, No. 1 (Jul., 1995), pp. 51-62
Published by: The University of Notre Dame
Stable URL: http://www.jstor.org/stable/2426482
Page Count: 12
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The relative importance of hunger and temperature on grouping behavior in the whirligig beetle Dineutes assimilis (Coleoptera: Gyrinidae) was examined under controlled laboratory conditions. Well-fed beetles were significantly more likely to join groups at lower temperatures (91% grouping at 15 C vs. 71% at 25 C) whereas hungry beetles were less likely to join groups at any of the temperatures at which they were tested. Well-fed beetles that grouped were significantly closer together than hungry beetles that grouped. Grouped beetles were significantly less active at higher temperatures, but the activity level of nongrouped beetles was not significantly affected by temperature. Activity in nongrouped beetles was significantly affected by hunger levels. Our results show that temperature and hunger affect the dynamic decision making process of whirligig beetles to group or stay alone.
The American Midland Naturalist © 1995 The University of Notre Dame