Title

Conserving insects in the tropics: Describing and predicting insect-habitat relationships at local to regional scales

Date of Completion

January 2001

Keywords

Biology, Ecology|Biology, Entomology

Degree

Ph.D.

Abstract

Understanding the distribution of species is a fundamental question in ecology and is increasingly critical for developing conservation strategies. In this dissertation, I investigated the distributional patterns of dung beetle (Scarabaeinae, Scarabaeidae) assemblages and vegetation communities at multiple scales. I had four research objectives: (1) To characterize the correspondence between vegetation and insect communities at local scales, particularly across tropical rainforest-savanna ecotones. (2) To assess whether vegetation communities are effective conservation surrogates for insect species and assemblages at the landscape scale. (3) To develop predictive models of the distribution and abundance of insect species and assemblages. (4) To evaluate the conservation implications of major biogeographical intersection zones such as northeastern Bolivia. ^ At the local scale, dung beetle assemblages differed sharply across a forest-savanna ecotone, with almost no species overlap between the forest and savanna. Beetle abundance, biomass and species richness varied significantly among the forest, edge and savanna habitats. At the regional scale, scarabaeine beetle communities were differentiated at both levels of the vegetation classification currently in place for the study region, lending support to the use of vegetation-based conservation planning as a reasonable strategy for conserving faunal taxa. ^ I integrated remotely sensed data and field-collected information on scarabaeine beetle assemblages to develop a series of multivariate models of scarabaeine biomass, species richness, and assemblage composition. The predictive ability of the models suggests that detailed information on the ecological and physical requirements of insect species may not always be necessary to estimate insect assemblage composition or structure. Instead, remotely sensed data may be utilized to construct generalized models of these biological phenomena. ^ Targeting the regions where biogeographic assemblages intersect presents conservationists with a strategy that operates at multiple scales and may achieve significant economy by focussing on areas that satisfy many conservation criteria. Several short- and long-term benefits of conserving these “biogeographic crossroads” are discussed using a combination of data on Scarabaeine beetles in Bolivia and on other taxa and locations from the literature. Biogeographic crossroads appear to be areas of high conservation priority and opportunity and require increased attention in the conservation priority setting process. ^