The ups and downs of phasmid (Insecta: Phasmida) phylogeny: Transcriptomic and legacy sequencing data unravel the high and low-level relationships of stick insects

The stick and leaf insects are a group of animals exhibiting a wide range of morphological diversity. Well-known for their camouflage, they masquerade as twigs, leaves, bark, and even lichen. These herbivorous insects spend most of their lives in the canopy and are seldom encountered- so much so that few entomologists have the expertise to properly survey their diversity in an area (Bradler and Buckley 2018). Even though Phasmida boasts some of the most charismatic insects on the planet, e.g. the longest and one of the rarest insects in the world, they remain an order which still lacks a robust and high-level phylogenetic analysis (Bradler and Buckley 2018). Recent efforts to boost both next generation sequencing (NGS) data and taxon sampling in stick insects have resulted in an improved, contemporary understanding of stick insect evolutionary relationships; however, each of these analyses suffer from a singular, and thus limited scope. To ameliorate these limits, I reconstruct a phylogeny which bolsters both NGS data and increased taxon-sampling to provide the best possible view of phasmid relationships. First, 61 transcriptomes representing all major phasmid lineages are used to create a well-supported phylogenetic backbone. Next, I use this phylogeny to constrain legacy data for ~500 additional taxa. This combined approach provides both robust high-level relationships from NGS data and solid low-level relationships achieved by increased taxon-sampling with currently available legacy data. As such, this analysis provides the most comprehensive stick insect phylogenetic analysis to date.