GENETIC-VARIATION OF MICROSATELLITE AND MITOCHONDRIAL-DNA MARKERS IN BROAD WHITEFISH (COREGONUS-NASUS) IN THE COLVILLE AND SAGAVANIRKTOK RIVERS IN NORTHERN ALASKA

There has been concern that a causeway leading to oil production facil ities in the Alaskan Beaufort Sea could affect the extent of emigratio n from, and immigration into, a population of broad whitefish (Coregon us nasus) in the Sagavanirktok River. To assess this, we analyzed the genetic relationships of the broad whitefish populations in the Sagava nirktok River, and the nearest adjacent population, in the Colville Ri ver. Three microsatellite loci from the nuclear genome, and the NADH-I gene of mitochondrial DNA (mtDNA), were analyzed. Diploid genotypes w ere determined with PCR amplification of the microsatellite loci, and mtDNA genotypes were identified with PCR amplification followed by seq uencing of 798 nucleotides. Several alleles were identified at each lo cus and both populations had high levels of genetic variation. There i s significant differentiation of the Sagavanirktok River and Colville River broad whitefish stocks for the three microsatellite loci (F-ST = 0.031) but not mtDNA (F-ST < 0.001). Possible explanations for the lo wer level of differentiation of mtDNA than microsatellites include fem ale-mediated gene flow between populations, skewed sex ratios, natural selection, or mutation. The results indicate that there is limited ge ne flow between the Colville and Sagavanirktok rivers, which represent semi-isolated spawning populations.