PS 8-101 - BIOTIC and temporal influences on spatial distribution of dominant and subdominant ground-foraging ants in a tropical agroecosystem

Monday, August 8, 2011
Exhibit Hall 3, Austin Convention Center
Katherine K. Ennis, University of California, Santa Cruz, Santa Cruz, CA and David J. Gonthier, School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI

Communities are structured by many of the same factors that govern regional species distributions. However, communities in comparison may be more strongly structured by interactions between species, or groups of species. We studied the relative effects of biotic and temporal factors on local distributions of dominant and subdominant ground-foraging ants in a coffee agroecosystem of southern Mexico. Prior research demonstrated the positive influence of a dominant arboreal nesting ant species (Azteca instabilis) on the local ground foraging ant richness. Based on these findings we ask if the increase in species richness surrounding A. instabilis nests may be caused by differential effects of A. instabilis on dominant and subdominant ground-foraging ant species. To answer this question, we surveyed ground-foraging ants in four spatially explicit sites surrounding A. instabilis nests during June 2009 and June 2010. We then determined the probability of subdominant ant presence with generalized linear models according to six factors: (1) distance from the dominant arboreal ant, A. instabilis; (2) presence of ground-foraging dominant ant; (3) previous presence of subdominant species; (4) ground cover; (5) relative tree density; and (6) site effect.


Preliminary results show that the strongest overall influence on the presence of a subdominant ant in 2010 came from the prior presence of a subdominant species (June 2009). The distance to A. instabilis nests also had a strong positive influence on the presence of a subdominant species. The presence of a dominant ant did decrease the probability of a subdominant ant species presence. Site effect, ground cover and relative tree density had comparably lower influences on the probability of a subdominant’s presence. These results are supportive of the idea that A. instabilis effects different ant groups differentially based on their abundance within ant community. Furthermore, the results indicate that communities may be more strongly influenced by local species interactions between groups of species than by other local factors.

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