Population genetics of Anelosimus eximius (Araneae: Theridiidae)

Abstract

Anelosimus eximius is a cooperative, group-living neotropical spider. Colonies consist of up to several thousand individuals, and colonies may be aggregated into local colony clusters. The colony clusters are patchily distributed, and are often separated from their neighbors by a km or more. In this study individuals were collected from colonies located in Panama and Suriname. These individuals were subjected to horizontal starch gel electrophoresis and screened for polymorphisms in 46 enzyme systems. A total of 51 scorable loci were found, of which seven were polymorphic. The results were analyzed with Wright's F statistics which were used to investigate the amount of genetic differentiation in the population attributable to subdivision of the population into colonies, colony clusters, local populations and the geographic regions of Panama and Suriname. Most of the genetic differentiation in the A. eximius sampled was due to subdivision of the population into colony clusters and into geographic regions. There was no evidence of differentiation among colonies in a colony cluster, and little differentiation among collection sites within Panama or Suriname. In contrast, within a local population, samples from adjacent colony clusters were sometimes fixed for different alleles at one or more loci, and the Panama and Suriname samples were fixed for different alleles at three loci.