Determinants of regional species richness: an empirical analysis of the number of hawkmoth species (Lepidoptera: Sphingidae) on the Malesian archipelago
Article first published online: 24 FEB 2006
Journal of Biogeography
Volume 33, Issue 4, pages 694–706, April 2006
How to Cite
Beck, J., Kitching, I. J. and Eduard Linsenmair, K. (2006), Determinants of regional species richness: an empirical analysis of the number of hawkmoth species (Lepidoptera: Sphingidae) on the Malesian archipelago. Journal of Biogeography, 33: 694–706. doi: 10.1111/j.1365-2699.2005.01418.x
- Issue published online: 28 MAR 2006
- Article first published online: 24 FEB 2006
- geographic information system;
- general linear model;
- island biogeography;
- life history;
- range size;
- species–area relationship;
- Southeast Asia
Aims Major patterns and determinants of the species richness of Sphingidae in the Malesian archipelago were investigated, including a distinction of richness patterns between subfamilies and range-size classes.
Location Southeast Asia, Malesia.
Methods Using a compilation of specimen-label data bases, geographic information system (GIS)-supported estimates of distributional ranges for all Sphingidae species of Southeast Asia were used to assess the species richness of islands. Range maps for all species and checklists for 114 islands can be found at http://www.sphingidae-sea.biozentrum.uni-wuerzburg.de. Potential determinants of the species richness of islands were tested with general linear models.
Results The estimated species richness of islands in the region is determined by biogeographical association, seasonality, availability of rain forest and island size. Species–area relationships are linear on a semi-logarithmic representation, but not on a double-logarithmic scale. Species richness of all sphingid subfamilies is influenced by biogeography. The presence of large rain-forest areas affects mainly Smerinthinae, whereas distance from continental Asia is conspicuously irrelevant for this group. Widespread rather than geographically restricted species shape the overall distribution patterns of species richness. The altitudinal range of islands does not significantly affect species-richness patterns, but its potential effects on geographically restricted species are discussed.
Main conclusions As well as being affected by climatic and vegetation parameters, sphingid species richness is strongly influenced by a historical, directional dispersal process from continental Southeast Asia to the Pacific islands. This process did not apply equally to species of different taxonomic groups or range sizes. Widespread species decline in species richness towards the south-east, whereas geographically restricted species exhibit an inverse pattern of species richness, probably because speciation becomes more important in this group within the more isolated island groups.