Intraspecific Phylogeography of the American Brook Lamprey,Lethenteron appendix(DeKay, 1842)

Abstract

Variation at two mitochondrial DNA regions was used to assess the phylogeographic history of the American brook lamprey, Lethenteron appendix, a widespread and typically non-parasitic species in eastern North America. Little differentiation (<0.2%) was observed among populations throughout its range. Specimens of putatively parasitic individuals had sequences identical to non-parasitic individuals. Additional sequences from other members of the genus Lethenteron also demonstrated little or no differentiation with American brook lamprey (<1.2%). These results support the hypothesis of a recent range expansion of the American brook lamprey. Further, the absence of variation among several of the species of Lethenteron suggests a recent origin of multiple non-parasitic species with insufficient time for lineage sorting or ongoing gene flow among populations of a trophically polymorphic species. This study calls into question the current species diversity of Lethenteron.