Odonata origins, biogeography, and diversification in an Eastern North American hotspot: Multiple pathways to high temperate forest insect diversity

1. We assessed the origins and historical biogeography of a rich regional odonate fauna in New York State (NYS), Northeastern United States. 2. We computed North American (NA) range centres and NYS range margins and reviewed the taxonomic literature to provide a useful phylogenetic framework for the fauna. We analysed results from a newly completed Odonata atlas using generalised linear ANOVA models to assess the effects of species' origins and zoogeographic affinities on relative frequency and extinction risk metrics. 3. Phylogenetic reconstruction based on taxonomic nomenclature revealed different patterns of diversification. Zygoptera in NYS is mainly of neotropical origin ~ 60 Ma displaying a pattern of tropical conservatism, but with a burst recent of Plio-Pleistocene speciation in certain groups. Alternatively, Anisoptera contains crown group endemic taxa and other very old lineages from the Mesozoic era before the breakup of Pangaea, highlighting the evolutionary significance of the Appalachian Mountains as an important global centre of temperate forest freshwater diversity. 4. These high regional levels of odonate diversity have been brought about by at least three different mechanisms: dependence on forests, predominance of non-ecological speciation mechanisms, and niche conservatism across hundreds of millions of generations. 5. NYS lies at a crossroads of both ancient and more recent Odonata evolution comprising separate boreal, temperate, and tropical faunas. Those species encountered less frequently and having higher overall extinction risk metrics generally tended to be the boreal species on the rear edge of their range, a widespread phenomenon for the insects of many regions generally attributed to ongoing climate change.