An
exploration of factors influencing lotic insect
species richness**
NEAL J. VOELZ1 and J. VAUN MCARTHUR2,*
1Department
of Biological Sciences/MS 262, St. Cloud State University, St. Cloud, Minnesota
56301,
USA
(e-mail: nvoelz@stcloudstate.edu); 2Savannah River Ecology Laboratory,
University of Georgia,
Drawer
E, Aiken, South Carolina 29802, USA; *Author for correspondence (e-mail: Mcarthur@srel.edu;
fax: 803-725-3309); **Address for reprints: Reprints Department,
SREL, Drawer E, Aiken, South Carolina 29802, USA
Received 20 April 1999; accepted in revised form 31
January 2000
Abstract.An understanding of factors that influence species richness of lotic
insects is generally lacking.We present comparative data on aquatic insect species
richness from several North American and other
streams.Factors
Such as large sample numbers and drainage area (species area relationships) are
not significant predictors of' species richness across the streams we examined.We explore several hypotheses
regarding the origins and maintenance of species richness using Upper Three
Runs Creek (UTR), South
Carolina, USA, as a reference stream.UTR has the highest species richness of any stream in the Western
Hemisphere.Hypotheses
examined included historical, regional and local processes such as: (1)
Evolutionary time, (2) disturbance regime/environimental variability, (3)
temperature/evolutionary-speed, (4)
productivity, and (5) habitat heterogeneity.Of these hypotheses, we suggest that productivity and habitat
heterogeneity appear to contribute most to the high species richness found in
UTR.We believe that multi-
disciplinary analysis of other streams is necessary because without this crucial
information our knowledge
of, and desire to protect biodiversity in streams will be wanting.
