Preliminary phylogeography of Synuchus dubius (Coleoptera: Carabidae) in Arizona’s Madrean Sky Island Archipelago

The Madrean Sky Island Archipelago is a natural laboratory within which to study the relation between landscape structure and genetic variation across time.  This region is located within the southwestern United States and northwestern Mexico and is composed of over 60 isolated mountains that span the gap between the Rocky Mountains to the north and the Sierra Madre Occidental to the south.  These mountains are called "Sky Islands" because they contain discrete patches of high elevation woodlands surrounded by a sea of desert and/or grassland.  For species that require a montane environment, the surrounding desert acts as a barrier preventing them from dispersing between mountain ranges.  The result is a lack of contemporary gene flow between Sky Island populations of flightless, poorly dispersing species.  However, during the Pleistocene (>10,000 years ago), there were opportunities for gene flow.  The climate within the region was much cooler and wetter; woodland habitat patches were larger, connecting many of today’s isolated mountain ranges.  To infer the historical corridors and barriers to population movement for this region, we used COI data for Synuchus dubius (Coleoptera: Carabidae), a flightless ground beetle species restricted to the isolated, high-elevation pine woodland patches of this region.  Here we present a preliminary COI phylogeny of S. dubius populations within the Madrean Sky Island Archipelago and introduce the utility of ddRADseq and next-generation sequencing to provide finer resolution within this phylogeographic framework.