Mitochondrial DNA Analysis of Mid-Atlantic Populations of Brook Trout: The Zone of Contact for Major Historical Lineages

Abstract

We tested the hypotheses that brook trout Salvelinus fontinalis in the mid-Atlantic range are transitional in phylogenetic assemblage structure and that this structure provides evidence for historic, formative geomorphological events in this region. Mitochondrial DNA (mtDNA) restriction fragment length polymorphisms were examined in brook trout from Maryland. Population genetic structure and intraspecific divergence were determined and compared with the results of previous work throughout the mid-Atlantic range of brook trout. A total of 29 mtDNA haplotypes was analyzed, including 15 previously undetected in brook trout. Phylogenetic analysis revealed three major assemblages in Maryland, two east and one west of the Ohio River−Chesapeake Bay drainage divide. Analysis of molecular variance indicated that drainage basins within the two major drainages were the major units of population division. These results suggest that brook trout populations in the mid-Atlantic should be managed as major assemblage groups based on mtDNA descent.