Early caddisfly (Insecta: Trichoptera) evolution and phylogenetics

Comprising over 14,400 named species, caddisflies (Insecta: Trichoptera) are the most speciose strictly aquatic insect order. They are sister group to the megadiverse order Lepidoptera. While Lepidoptera exist primarily on land, Trichoptera are almost exclusively freshwater insects. They are well known to fishermen and amateur collectors for the intricate tube cases and fixed retreats the larvae construct with silk. The order comprises two suborders: Annulipalpia, the net spinners and fixed retreat makers, and Integripalpia, the tube case makers, which now include the paraphyletic “Spicipalpia”, the free-living, tortoise case, and purse case makers. Despite multiple attempts to unravel their phylogeny, many of the relationships and associated evolutionary transitions among the suborders and families remain intractable. Of particular interest is determining the group (family or suborder) that is sister to the rest of the order. Several hypotheses have been posited, but few have been well supported. Understanding the relationships among these taxa will play an important role in reconciling the disparate life histories of Trichoptera and Lepidoptera. In an attempt to unravel trichopteran relationships, we construct a phylogeny by targeting and sequencing over 900 single copy exons for over 150 individuals representative of the diversity within the order. We analyze these data with novel model selection and partitioning techniques paired with smart data exclusion to minimize systematic error and help us better understand the remarkable diversity and behaviors exhibited within Trichoptera.