INTRODUCTlON ,. . The foundation of most evolutionary theory rests upon inferences drawn from geographic variation or upon the verification of predictions made about it. The study of geographic variation occupies a central position in evolutionary biology. .. because geographic variation is ordinarily the smallest amount of evolution that can be detected in nature and because evolutionary theor...

Salamander populations of the Plethodon jordani species complex form a challenging system for applying the general lineage concept of species to diagnose population-level lineages. The present study reports and analyses mitochondrial-DNA haplotypes ( ∼ 1200 nucleotide bases from the genes encoding ND2, tRNA Trp , and tRNA Ala from 438 salamanders) from 100 populations representing six species o...