4. The shovel-nosed salamander, Desmognathus marmoratus, is a totally aquatic, endemic species found in high mountain streams in the Appalachian Mountains of Tennessee, North Carolina, South Carolina and Georgia. No gene flow occurs between river drainages due to the completely aquatic lifestyle of this salamander. Populations on either side of the Tennessee Divide (Tennessee and N. Carolina vs. Georgia and S. Carolina) have no morphological differences between them. A phylogeny based on mtDNA sequences (Jones et al. 2006) showed, however, that populations on either side of the Tennessee Divide showed greater than 14% sequence divergence and were well supported, separate, monophyletic lineages. Salamanders collected from drainages on both sides of the Tennessee Divide were brought into the laboratory and observations confirmed that salamanders from Tennessee would mate with salamanders from Georgia and made viable and fertile F1 and F2 offspring. Based upon your understanding of different species concepts (biological, morphospecies, phylogenetic), how would each classify these shovel-nosed salamanders (i.e., separate species or the same species, and why?). Under which type/mode of speciation are these salamanders likely to be diverging on opposite sides of the Tennessee Divide?
