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Insect activity often
follows gradients of increasing moisture. We studied ant activity,
size, and diversity in 4 microhabitats along three moisture gradients in
a Panamanian rainforest. Ant activity increased by 25% from the dry
to the wet season, and >200% on a topographical gradient from a ravine
to an exposed plateau. Activity varied little from day to night.
Three microhabitats--tree trunk, shrub, and litter--showed different responses
to these three gradients. The size distribution of the species pool
(n=62) was right skewed, but the average size of ants at a bait was strongly
bimodal. Ants active in moister times and places were not significantly
smaller. We suggest that gradients of desiccation risk and food availability
are the two most likely causes of these patterns. Two temporal niche
axes (daily and seasonal) showed little species specialization, but half
of the common species could be categorized as litter or plant microhabitat
specialists. |
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