Phylogenetic relationships, expanded diversity and distribution of Crassiphiala spp. (Digenea, Diplostomidae), agents of black spot disease in fish.

Crassiphiala is a monotypic genus of diplostomid digeneans and is the type genus of the subfamily Crassiphialinae. The type species Crassiphiala bulboglossa parasitizes kingfishers in the Nearctic and has a Neascus-type metacercaria that encysts on fish intermediate hosts, often causing black spot disease. While recent molecular phylogenetic studies included some members of the Crassiphialinae, no DNA sequence data of Crassiphiala is currently available.

The origin of Phoxinus eos-neogaeus unisexual hybrids.

Phoxinus eos-neogaeus unisexual hybrids (Cyprinidae, Pisces) are among the few vertebrate taxa known to reproduce clonally by gynogenesis. These taxa have a broad distribution in North America, mostly located in regions previously covered by the last Pleistocene ice sheet. To assess whether asexual hybrids dispersed from glacial refuges at the end of the Pleistocene or they originated from current hybridization events, genetic diversity of mitochondrial DNA (mtDNA) sequences and microsatellite loci was determined in populations from 16 different sites in the Mississippi-Missouri River (Nebraska and Montana), Rainy River-Hudson Bay (Minnesota), and St Lawrence River (Quebec) drainages.

Phenotypic consequences of genetic variation in a gynogenetic complex of Phoxinus eos-neogaeus clonal fish (Pisces: Cyprinidae) inhabiting a heterogeneous environment.

We examined the genetic composition, habitat use, and morphological variation of a Phoxinus eos-neogaeus unisexual hybrid complex and its sexually reproducing progenitor species inhabiting beaver-modified drainages of Voyageurs National Park, Minnesota. In addition to the single diploid P. eos-neogaeus gynogenetic clone, triploid and diploid-triploid mosaic biotypes were present at our study sites.

Fish recruitment, dispersal, and trophic interactions in a heterogeneous lotic environment.

I examine how dispersal of juvenile creek chubs (Semotilusatromaculatus) from beaver ponds into adjacent stream environments interacts with temporal abiotic variability to influence fish foraging, growth, and long-term persistence in the lotic ecosystem. Minnow trapping in upstream and downstream beaver ponds, along with weir traps used to monitor directional movement, indicated that most chubs colonized the stream from the downstream beaver pond. Large annual fluctuations in density of age 0 creek chubs occurred in the stream over a 10-year sampling period.