Phylogenetic Relationships among Palearctic and Nearctic Whitefish

We recently documented the existence of two highly distinct mitochondrial DNA (rntDNA) phylogenetic groups of Coregonus sg. in Beringia in the absence of geographic separation. Po test whether this resulted from secondary intergradation of two groups that evolved in allopatry in Eurasia and Beringia, rntDNA restriction-fragment-length pslyrnorphisms of 21 0 whitefish representing 22 populations from Europe and Siberia were compared with rntDNA variation observed among 581 fish from North America. Results confirmed that Beringia represents a zone of secondary contact among endemic whitefish and a group of Eurasian origin. All Beringian populations clustered much more closely to Eurasian populations than other North American ones. We also compared mtDNA variation among Palearetic populations with that observed in North America. European populations clustered into two major rntDNA groups that exhibited a strong geographic pattern of distribution, independent of the rnorpholsgica[ variation observed among populations: awe dominated all the more northern populations and extended to Alaska-Yukon; the second largely dominated samples from central alpine lakes, and was absent from Beringia. These resuits suggest that central alpine lakes and northern Europe were postglacially recolonized by two genetically distinct whitefish groups that most likely evolved in al lopatry followed by limited intergradation.