Genetic relationships among populations of northern pike (Esox lucius)

We assessed genetic variation, using microsatellite markers, in 14 populati ons of northern pike (Esox lucius) in the North Central United States and i n six populations from Quebec, Alaska, Siberia, and Finland. Eight of 13 lo ci examined were polymorphic in at least one population with an average het erozygosity at all loci and across all populations of 0.14. The R-st and F- st values indicated differentiation among populations (R-st = 0.61, F-st = 0.42). Although microsatellite variation found in northern pike was much lo wer than that found in sympatric and other fish species, the polymorphisms differentiated populations of greater geographical proximity than was possi ble in prior studies using allozymes and mitochondrial DNA. We generated UP GMA-clustering phenograms based on five genetic distance measures with 2000 bootstrap replicates per measure. All measures yielded highly repeatable p opulation structure between continents (supporting values = 92.4-100%) and within Finland (42.3-98%). Four measures differentiated the Alaskan populat ion and Young Lake (Great Lakes drainage) from other North American populat ions (56.6-87.7%). Relationships among other North Central United States po pulations were unclear, as indicated by low supporting values. Results supp ort the hypotheses of one refugium in the North Central United States and m ore than one refugium in Europe during the last glaciation.