Intraspecific Phylogeography of the Least Brook Lamprey (Lampetra aepyptera)
We examined the phylogeography of the Least Brook Lamprey (Lampetra aepyptera) to recognize phylogenetically distinct clades within this species and to estimate the relative contributions of vicariance and dispersal to the distribution of genetic variation. A combined data set from mitochondrial ND3 and control region sequences identified 23 unique haplotypes among 21 populations. Eleven highly differentiated clades within L. aepyptera were detected. Their distributions correspond to different drainages and/or locations within drainage. Clades differed by an average of 4.5% (range 2.5–9.0%) sequence divergence. Only two haplotypes were shared among any populations. Considerable differentiation among adjacent drainages and limited sharing of haplotypes suggested little historical or contemporary gene flow. Although clades were highly differentiated, resolution of clade relationships was limited. The presence of highly differentiated clades in different drainages suggests that vicariance has had a profound effect on the distribution of genetic variation in L. aepyptera. The lack of resolution of clade relationships within this species suggested a single event that simultaneously isolated many of these populations. Rising sea levels causing a marine incursion into the Mississippi embayment during the Pliocene could have been such an event.Abstract
Map of the sample localities for L. aepyptera. Locality information can be found in Table 1. C refers to the Cumberland River locality for the ND3 sequence from Docker et al. (1995).
The 50% majority-rule consensus tree of 74 equally parsimonious trees for the combined ND3/control region data set. Numbers next to the nodes indicate bootstrap values. Tree length = 218. Letters next to Terrapin, Schultz, and Gaylor refer to the multiple haplotypes listed in Table 1. Numbers in parentheses identify the locality number.
Statistical parsimony network for the combined ND3/control region data for the 23 L. aepyptera haplotypes. Numbers along the connections indicate the number of steps between haplotypes. Unlabeled connections indicate a single step. Small circles indicate hypothetical haplotypes.
Contributor Notes
Associate Editor: S. A. Schaefer.