MEDEIROS, Matthew J; University of California, Berkeley: Repeated evolution of flightlessness in cave-dwelling moths.

Most insects are capable of sustained flight, but flightlessness has evolved independently several times in insects, especially in females. Certain habitats, such as caves, seem to be correlated with an increased likelihood of evolving flightlessness. However, it is largely unknown whether related lineages that have invaded a habitat associated with flightlessness will repeatedly converge upon a non-flighted state. I investigated the number of times that flightlessness has independently evolved in females of the genus Schrankia, a group of Noctuid moths that has invaded caves on the Big Island of Hawaii. Cave-adapted females of this genus are flightless while the males are capable of flight. I collected Schrankia moths from a total of five caves on three separate volcanoes and repeatedly dropped individuals in an experimental chamber recording whether they were capable of sustained flight or immediately fell to the bottom of the chamber. I also collected related surface species and sequenced 527bp of the mitochondrial gene COI for a total of 20 species. The results from the drop-test and the COI gene tree showed that this group of moths has invaded caves at least twice and that flightlessness has evolved in each of these cave-dwelling lineages. Based on the age of the caves in which Schrankia occur, flightlessness has evolved in as little as 0.1my. These results suggest that at least in some groups, lineages that invade similar habitats may rapidly converge on similar traits.