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THE PHYLOGENOMICS OF THRIPS (THYSANOPTERA)
Thrips, Thysanoptera, represent an ancient (~407 m.y.a.) order of ~6000 tiny insects from 9 families. Despite the small size of the order, thrips have a diversity of life histories, diets, and survival strategies. Thrips represent a challenge to fieldworkers and axonomists alike due to the morphological similarity between species and the lack of homologies between families. Recent
molecular evidence has reopened debate over the phylogenetic relationships of the families of Thysanoptera.
In this thesis we use genomic approaches to elucidate and clarify the early nodes in order to answer evolutionary questions about the Thysanoptera, their mitochondrion symbiotes, and their
coevolutionary interactions with a group of economically important viruses; tospoviruses. Our results support previous ordinal hypotheses and show families in both sub-orders radiating
around the emergence of the angiosperms ~120 m.y.a. We show that all thrips lineages likely have highly rearranged mitochondrial genomes, even on an intraspecies level, and that this rearrangement phenomena occurs very quickly in evolutionary time. We provide comment on the caution that must be taken with mitochondrial loci in any phylogenetic analysis with this new
evidence and argue for the impact of among-site-rate-heterogeneity to be further investigated within thrips hylogenetics. We show that much more data is needed before thrips and tospovirus relationships can be fully elucidated but that two dueling hypotheses are emergent from our studies: either 5 very new separate vector/virus relationships, or one very old relationship that has been lost by the vast amount of thrips. We call for targeted taxa selection and show how new genomic methods can target certain taxa based upon the identification of
assembled proteins from illumine shotgun read data.