Historical and Ecological Factors in the Biogeography of Aposematic Neotropical Butterflies

Open Access
Publisher Website
Google Scholar
Abstract
SYNOPSIS. Quantitative analysis of low-level (mostly subspecific) geographic differentiation of aposematic color patterns in three groups of forest butterflies (Heliconiini, Ithomiinae, and Troidini), in 1,550 half-degree quadrants throughout the Neotropics, indicates four principal species-endemicity regions, 44 principal subspecies-endemicity centers, and 300 quadrants of subspecies hybridization. The endemism centers are different in outline but nearly identical in position for each of the three ecologically different groups. Basic data on present and past physical environments (climate, soils, geomorphology, and vegetation structures), when integrated into maps, show 1) regions of favorable ecological conditions for forest organisms in the present, 2) regions of environmental conformities and rapid transitions in the present, and 3) regions of high probability for humid forest persistence during the major landscape changes at the end of the last glacial period, 13,000–20,000 yr ago. Species diversity (a local phenomenon) is readily related to favorable modern ecological conditions and environmental microheterogeneity, promoted by unpredictable mild disturbance. Biogeographical patterns of evolution at the level of regional subspecies correlate very well with presumed paleoecological conditions. The biogeographical data also support an hypothesis of differentiation resulting from areas of rapid environmental change; most of the hybridization quadrants fall within transition zones. There is lower correlation between centers of endemism and zones of en vironmental conformity, but some individual cases of differentiation in the butterflies may be adequately explained by modern ecological factors. Species presently undergoing differentiation in isolated habitat islands (Amazonian savannas and high-altitude Andean forests and paramos) may offer the best opportunities for observation of evolutionary processes in the present.

This publication has 0 references indexed in Scilit: