Matthew Van Dam
Phylogeography of sand dunes in the desert Southwest
Island systems have been indispensable in understanding the processes generating biodiversity. Examples from the Galapagos, Caribbean and Hawaiian archipelagos demonstrate the utility of islands for the study of adaptation, community assembly, and speciation. In addition to oceanic islands, habitat islands are also of great interest to evolutionary biologists. My research focuses on the biogeography of sand dunes in the Southwestern deserts of North America. I am examining the role in which dune formation has played in shaping the distribution and phylogenetic patterns of taxa living in this unique continental archipelago. My focal taxa include Rhaphiomidas (Diptera: Mydidae), flightless sand treader crickets Macrobaenetes and Ammobaenetes (Rhaphidophoridae) and flightless weevils Trigonoscuta (Curculionidae) as well as the fringe toe lizards Uma.
Dispersal paths measured between the sand dunes and deserts of North America, the blue polygons were coded as biogeographic regions. Path lengths in red used to calculate dispersal rate multiplier.
Biogeographic reconstructions for the sand treader crickets using BioGeoBEARS (Matzke 2013). Comparison of biogeographic reconstructions between constrained dispersal without founder event speciation "jump dispersal" j=0 (A), and where founder event speciation is allowed (B). Also note the improvement in the likelihood and less broadly distributed ancestral states in the jump dispersal model.