Are hyalella cryptic species communities stable throughout a season?

Recent studies on cryptic species of Hyalella amphipods suggest that they can coexist in communities via niche partitioning. However, the stability of these communities throughout the year has never been studied before. We examined the structure of a community of Hyalella amphipods living in the littoral zone of a North American temperate lake during the open-water season from May to November 2007. Two cryptic species were distinguished using the mitochondrial CO1 gene. No morphological differences were detected between them at any time of the open-water season. No succession in time was observed between the two species inhabiting the study site. The community was stable through the open-water season, one species being always more abundant than the other. Further investigation suggests that the dominant species is a permanent resident whereas the other one could be maintained at the study site via migration from sites aside.