“I WOULD SWIM 500 MILES”: UNEXPECTED CONNECTIVITY OF NAUTILUS POPULATIONS ACROSS THE INDO-PACIFIC (Invited Presentation)

Nautiloids have an extensive fossil record dating to the Cambrian. Extant nautilus appear to have changed very little from their ancestors, giving them the designation of “living fossils”. Nautiluses are threatened by harvesting for the decorative shell trade, particularly in the Philippines, but conservation efforts can be aided by rigorous population analyses. The family Nautilidae has a disputed number of extant species ranging from two to nearly a dozen. We sought to determine how distinct nautilus populations are across the Indo-Pacific using both publicly available and novel sequencing data. Using genetic markers, we show that nautiluses from the Philippines, Eastern Australia (Great Barrier Reef), Vanuatu, American Samoa, and Fiji fall into distinct phylogeographic clades. We also show that there are likely two species of extant Nautilus – N. pompilius and N. macromphalus – and that nautilus identified in other studies as N. belauensis, N. stenomphalus, or N. repertus are likely N. pompilius individuals or populations displaying a diversity of morphological characters. This suggests that there is significant phenotypic plasticity within N. pompilius and that distant island populations are unexpectedly connected.