PARENT SESSION
Poster Session #3: Invertebrate Ecology.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Latitudinal gradient in insect diversity from Texas to Costa Rica.

Pearson, Clark^*,1, Horton, Howard², Dyer, Lee¹, ¹ Tulane University, New Orleans, LA.² University of Northern Colorado, Greeley, CO

ABSTRACT- The latitudinal gradient in species richness is one of the most striking patterns in community ecology. Various factors are proposed to cause and maintain this gradient including among others, climatic stability, and biotic interactions. We addressed the general question: to what degree do abiotic versus biotic factors affect the maintenance of latitudinal gradients in insect diversity? We investigated the species richness of grass/forb dwelling insects from Texas to Costa Rica. Nested within latitude we sampled two community types: forests and fields. We identified the insects to family and morpho-species. This design allows for a realistic comparison between geographic areas because of community similarities between the forests and fields at different latitudes. We found three times the number of families and morpho-species in tropical versus temperate areas. We found no difference between community types in either family or morpho-species richness. Further investigations revealed that the major orders of insects responded differently to these biotic and abiotic forces. Diptera, Coleoptera and Hymenoptera were more abundant in tropical areas and we detected no difference between community types suggesting the importance of abiotic forces in maintaining species diversity. In contrast Heteroptera and Orthoptera were more abundant in the forests than the fields and we detected no difference in latitude suggesting the importance of biotic forces in maintaining species diversity for these orders.

KEY WORDS: Latitude, Gradient, Insect, Richness