The Mummichog DNA Consensus Tree

It doesn't look great graphically here, but this is the guts of our results looking at the mitochondrial DNA cyt-b gene of Fundulus heteroclitus populations along the Atlantic seaboard. (Click on the figure to enlarge it.) The F. similis at the top is our outgroup. Using the Tamura-Nei algorithm within the UPGMA tree-building method, the big news is that there is indeed a significant split between the northern populations (Cape Cod, Nantucket Island and Wiscasset, Maine) and southern populations (Chincoteague and Virginia Beach, Virginia; Charleston, South Carolina; and Sapelo Island, Georgia). There are also interesting differences between the Virginia and more southern populations, reflecting a longer history allowing more genetic changes to appear. Our interpretation is that the northern populations show the low diversity due to being descended from a low founding population about 13,000 years ago that remained largely isolated from further immigration from the south (a leptokurtic resettlement pattern). Kris' thesis is almost done, and with any luck he can defend in January. It's real biology!