Rapid microsatellite development for water striders by next-generation sequencing

Water striders have become a model system for studies of sexual conflict and coevolution, but progress is currently limited by a lack of genetic resources. Next-generation sequencing technologies offer the potential for rapid and cost-effective development of molecular markers and hold particular promise for model organisms in ecology for which no reference genome exists. We used Roche 454 sequencing of genomic DNA to identify microsatellite loci for the water strider Gerris incognitus. A modest sequencing volume generated 182,912 reads, of which 30,820 (16.8%) contained microsatellite repeats. We selected 23 loci for primer development, based on criteria that maximized the likelihood of amplifying polymorphic loci, and tested them in G. incognitus and the related species G. buenoi. Of the 16 amplifying loci, 10 yielded reliable amplification and detectable polymorphism, with an average of 6.1 alleles per locus (range: 2-12). These markers should facilitate new avenues of study, including postcopulatory sexual selection, population genetic structure, phylogeography, and sexual coevolution, for a key taxon in studies of mating conflict. The current study demonstrates an effective method for microsatellite development and shows that light sequencing of genomic DNA can provide numerous and highly variable markers.