Phylogenetic analysis ofHyalellacolonization in lakes recovering from acidification and metal contamination

Abstract

The freshwater amphipod Hyalella azteca (Saussure, 1858) is common throughout North America and is a popular organism for toxicity tests and assessment of an ecosystem’s health. However, recent studies suggest that this “species” may actually be a number of closely related species, possibly with distinct habitat requirements. The region in and around Sudbury, Ontario, has many lakes recovering from acidification and metal contamination with Hyalella slowly recolonizing the area. Analyzing mitochondrial cytochrome c oxidase I (COI) sequences, we find two major groups of Hyalella: one group associated with recolonization of the central, historically more contaminated set of lakes and a second group associated with the more distant, less impacted, lakes. Morphologically, these inner city amphipods are significantly larger than those observed in lakes farther away from the city. This study may provide a foundation for a better understanding of Hyalella species complex, as well as colonization routes, toxicological sensitivities, habitat requirements, and dispersal capabilities.