Document: ERI-3-65-2

Biogeographical patterns of butterfly species richness.

PORTER, E.* and B.HAWKINS

University of California at Irvine, Irvine, CA 92612, USA ¹

Abstract:
Studies on a variety of vertebrate taxa show that variation in species richness on continental scales correlates closely with contemporary climatic variables. Because the strongest correlates are generally measures of energy or productivity, previous researchers have concluded that energy availability is a likely determinant of species richness at this scale. There were two main objectives in our study. First, we wished to know whether similar patterns hold for insects. Therefore, we identified relationships between climatic variables and species richness for butterflies as a representative insect group. Second, to assess the generality of these relationships, we compared the relationships between butterfly species richness and climatic variables across four continents: North America, Europe, Australia and Africa (south of 20 degrees latitude). We found that PET is the strongest correlate with species richness in North America and Europe and AET is the strongest correlate for Australia and Africa. Our results suggest that PET has a clear effect on butterfly species richness but only for values below approximately 700 mm/year. Where PET is higher than 700 mm/year, AET is a better predictor of species richness. These results suggest that climatic variables, specifically measures of productivity and energy, are important determinants of species richness for butterflies, but different mechanisms operate in temperate versus tropical areas.

Keywords: biogeography, species richness, energy, productivity, butterflies

This abstract is being presented at: 2:45 PM in session:
Oral Session #53: Terrestrial Invertebrate Ecology.