PARENT SESSION
Poster Session 30: Invertebrate Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Resource discovery dynamics in ant communities.

Pearce-Duvet, Jessica^*,1, Feener, Donald^*,1, ¹ Biology Department, University of Utah, Salt Lake City, UT, USA

ABSTRACT- Competition between ant species is asymmetric and should result in community monodominance, as dominant species drive subordinate species to extinction through competitive exclusion. However, monodominance in ant communities is rarely seen. Species may trade off between dominance and discovery abilities; species skilled at taking over and defending a food resource may not be good at locating it initiallly. We examined the bait discovery in diverse ant communities at 5 sites in Arizona's Chiricahua Mountains in the summer of 2004. Bait types were varied: honey (20% and 80% conc), hot dog pieces (small and large), and crickets (small and large). The number of baits discovered and time to discovery were measured for a total of 9 genera. We found a significant difference in the number of discoveries of different bait types by different ant genera (² (27)= 79.4, p<0.01). We also found a significant interaction between genus and bait type on bait discovery time (F(16, 469)=1.77, p= 0.03). The bait size/conc did not affect discovery number or discovery time of the bait. There was also no correlation between a genus' number of discoveries and average discovery time. Pheidole found the most baits, with Temnothorax and Dorymyrmex second coming in second, but all three showed similar discovery times. These results suggest differences in ant abilities to discover food. Certain genera may specialize on particular foods in nature. The lack of a relationship between discovery number and discovery time may suggest that there are different ways to be a good discoverer; some taxa may be better able to detect bait signals whereas others may simply flood the environment with individuals, increasing discovery by increasing overall encounter probability. This interpretation is supported by pitfall trap data. Across sites, genera occurrence at baits differed from that predicted by pitfall trap abundances (T_s(18)=-3.15, p=0.002). Temnothorax occurs at a higher proportion of baits than would be expected based on its abundance in pitfall traps. In contrast, Pheidole occurred in a much higher proportion of pitfall traps relative to their appearance at baits. Differences in discovery abilities may promote species co-existence.

Key words: ant community ecology, resource discovery, species co-existence