ASPECT DIVERSITY IN MOTHS: A TEMPERATE-TROPICAL COMPARISON.

Abstract

This analysis attempts to answer, for assemblages of adult moths, whether the increased number of species in a tropical sample compared to two temperate samples represents an increase in the density of species packing in the community or an increase in the total ecological space occupied by the community as a whole. We view a species as occupying a niche defined by the interactions of that species with its environment, especially by its utilization of limiting resources. The increased species richness in some tropical habitats compared to temperate habitats can be related to either (a) an increase in the total niche space occupied by all species, (b) a decrease in the average size of the niche of each species, (c) an increase in the degree of niche overlap between species, or any combination of these factors. In this paper we approach the problem of species richness by assuming that the interactions of a species with the environment, which define its niche, are reflected in the morphological adaptations of the species. By placing species in an abstract multidimensional space ordinated by morphological characteristics, we can indirectly assess the relative roles of community niche size and species packing in variation in species number. We cannot, however, estimate niche overlap by this technique. We have analyzed the appearance of adult moths in two temperate communities and one tropical community. We assume that the cryptic appearance of most species (Fig. 1) is an adaptation to match the