Genetic determination of sub-species classification for the Banff longnose dace (Rhinichthys cataractae smithi)

A morphologically unique population of longnose dace was known to exist in the Cave & Basin Marsh in Banff, Alberta. These fish were thought to be geographically separated and designated as a distinct sub-species, the Banff longnose dace. The traditional taxonomic traits used for this classification have been called into question and may not have accurately reflected phylogeny but resulted from genotype, phenotype, or a combination of both. I assessed the validity of the Banff longnose dace sub-species classification using molecular genetic techniques. I also used this approach in combination with otolith microchemistry for extant populations of Cave & Basin Marsh longnose dace to determine migration between the Bow River and the Marsh.;Historically, two different evolutionary mtDNA lineages (Great Plains and Pacific) of the longnose dace came into secondary contact in the Cave & Basin Marsh. None of these lineages proved to be unique or restricted to the Marsh. Instead haplotypes from both extant and archived Marsh populations were found in several other extant Western North America longnose dace populations. However, current longnose dace collections in the Marsh revealed only the Great Plains lineage; the Pacific lineage was not found and appears to have been swamped out and extirpated from the region by the more numerous longnose dace of Great Plains lineage. This suggests that the missing Pacific lineage and the loss of the Banff longnose dace morphotype may be correlated. Irrespective of the causes for the unique morphology, my mtDNA evidence does not support the morphological evidence of a distinct sub-species.;Microsatellite DNA analysis revealed extant longnose dace populations from the Bow River and Cave & Basin Marsh were not significantly different from one another. The otolith microchemistry results complemented the genetic findings and indicated connectivity and movement of fish between the Marsh and the Bow River.;The lack of concordance between morphology and genetics, demonstrates the importance of using multiple criteria to determine taxonomy. My mtDNA results do not support the distinct subspecies status of the Banff longnose dace. Regardless of the subspecies status, the Banff longnose dace population represented a unique assemblage of fish that no longer exists in the Cave & Basin Marsh. The biogeographic distinction of this population demonstrates that it merited protection and designation. However, the designation of an extinct sub-species remains unresolved due to the unknown effects caused by the hot spring fed environment. Unless it can be proved that the morphological traits are heritable I would hesitate to use this evidence for designating subspecies status. I would, however, recommend that COSEWIC reassess the status of this sub-species from the extinction of Rhinichthys cataractae smithi to the extirpation of Rhinichthys cataractae dulcis from the Cave & Basin Marsh.