Variation in larval fitness of a black fly species (Diptera: Simuliidae) over heterogeneous habitats

Abstract

Habitats vary over landscapes, resulting in non-random distributions of organisms. In turn, habitat selection involves the interplay between choices made by individuals and the consequences of these choices. Larvae of Simulium ubiquitum Adler, Currie and Wood, 2004 (Diptera: Simuliidae) are filter-feeders that live in a variety of lotic habitats. Using larval size as a proxy for adult fitness, we examined whether size varied over a heterogeneous riverscape. Regression analysis showed a significant (P < 0.001) negative relation of larval size and stream temperature, depth and discharge, and a significant positive relation with stream width. Habitat selection, therefore, has fitness consequence for S. ubiquitum. No significant difference was found in head-capsule size between male and female final-instar larvae.

Keywords:

• Simulium
• fitness
• habitat selection

Acknowledgements

Partial financial support for this study was obtained from a grant from the US Environmental Protection Agency's Science to Achieve Results (STAR) programme, under the direction of Alabama Center for Estuarine Studies (ACES), awarded to J.W. McCreadie and P.H. Adler. Although the research described in this article has been funded wholly or in part by the US Environmental Protection Agency's STAR program, it has not been subjected to Environmental Protection Agency review and, therefore, does not necessarily reflect the views of the Agency, and no official endorsement should be inferred.