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Neurocordulia, commonly called shadowdragons, are crepuscular dragonflies, flying mainly at dusk. The genus comprises seven species, which occur across the eastern part of Canada and the United States. Here, we used targeted enrichment probes to sequence ~1000 loci for all specimens of each species, allowing for the first phylogenetic assessment of the genus. Additionally, we collected individuals of N. yamaskanensis from a population in Ontario, Canada, and used whole genome resequencing to estimate population structure. Beyond broadly reconstructing the phylogeny of Neurocordulia, we provided a comprehensive bibliography review of past research on the genus, a key to the species, and distribution models for each species. 

Species distribution models (SDMs) were created for 509 Nearctic and 402 Palaearctic species of dragonflies and damselflies (Odonata). Species occurrence data were assembled by reviewing databases of specimens held by significant Odonata repositories and through an extensive search of literature references for the whole of the Nearctic and Palaearctic (excluding China and the Himalayan region). Species were categorized as forest-dependent or non-forest-dependent (Nearctic only), as lentic or lotic-dependent, and according to conservation status. Predicted distributions were stacked for all species across their entire ranges, including areas outside of the Nearctic and Palaearctic. Species richness and corrected weighted endemism (CWE) were then calculated for each grid cell. We found a pattern of greater species richness in the eastern portion of the Nearctic, which can be explained by the higher aquatic habitat diversity at micro and macroscales east of the Rocky Mountains, promoting niche partitioning and specialization. In the Nearctic region, the southeastern US has the highest number of endemic species of dragonflies and damselflies; this degree of endemism is likely due to glacial refuges providing a foundation for the evolution of a rich and unique biota. In the Palaearctic, these maps show a clear pattern of decreasing diversity longitudinally, with species numbers dropping in the eastern half of Europe and remaining low throughout a large part of Russia, then increasing again towards Russia’s Far East and Korea. Areas with a high diversity of species assessed as threatened on the IUCN red list are largely restricted to the Mediterranean, Southwest Asia, and Japan, with clear hotspots found in the Levant and the southern half of Japan. 

Odonata comprise approximately 6400 species with extensive morphological and ecological diversity, specifically their colour variation, flight behaviour patterns, and breadth of ecological niches. Additionally, their phylogenetic placement within Insecta as descendants of the first winged insects make them ideal candidates for exploring evolutionary forces that have shaped diversity patterns (e.g., diversification rate shifts) as well as character evolution (e.g., flight behaviour, colour). Even though morphological and ecological traits are relatively well known for most of odonate taxa, the lack of well-supported phylogenetic hypothesis across Odonata have limited the capability of evaluating evolutionary phenomena in a comparative context. Previous studies using various taxon sampling schemes and data types (i.e. morphology, targeted locus approaches) to reconstruct odonate relationships failed to resolve several interfamilial relationships, specifically in groups with likely incomplete lineage sorting and/or introgression. Even though a recent study by Bybee et al. (2021) incorporated genomic-scale anchored hybrid enrichment (AHE) data for phylogenetic reconstruction, the relatively limited taxon sampling likely precluded resolution within the problematic groups. Our study, also targeting AHE loci, greatly expand taxon odonate genera, which resulted in 729 newly generated samples in a addition to 142 samples from Bybee et al. (2021) for a total of 831. With around 500 AHE loci, we aim to resolve historically difficult relationships and construct a robust ordinal phylogeny of Odonata, which will be used as the evolutionary framework to clarify taxonomic classifications and test evolutionary hypotheses regarding shifts in flight behaviours, colours, and diversification rates. 

More than 1.2 million distribution records were used to create species distribution models for 402 Palaearctic species of dragonflies and damselflies. On the basis of these diversity maps of total, lentic and lotic diversity for the whole of the Palaearctic (excluding China and the Himalayan region) are presented. These maps show a clear pattern of decreasing diversity longitudinally, with species numbers dropping in the eastern half of Europe and remaining low throughout a large part of Russia, then increasing again towards Russia’s Far East and Korea. There are clear differences in diversity patterns of lentic and lotic species, with lentic species being dominant in colder and more arid areas. Areas with a high diversity of species assessed as threatened on the IUCN red list are largely restricted to the Mediterranean, Southwest Asia, and Japan, with clear hotspots found in the Levant and the southern half of Japan. The diversity at species, generic, and family level is higher in the south of Japan than in areas at a similar latitude in the western Mediterranean. This is likely to be the result of the more humid climate of Japan resulting in a higher diversity of freshwater habitats and the stronger impact of the glacial periods in the Western Palaearctic in combination with the Sahara, preventing tropical African lineages dispersing northwards. 

Rarely have studies assessed Odonata diversity for the entire Nearctic realm by including Canada, the United States, and Mexico. For the first time, we explored Odonata diversity in this region according to a definition of natural community assemblages and generated species distribution models (SDMs). Species occurrence data were assembled by reviewing databases of specimens held by significant Odonata repositories and through an extensive search of literature references. Species were categorized as forest-dependent or non-forest-dependent, as lentic or lotic-dependent, and according to conservation status. Predicted distributions were stacked for all species across their entire ranges, including areas outside of the Nearctic. Species richness and corrected weighted endemism (CWE) were then calculated for each grid cell. We found a pattern of greater species richness in the eastern portion of the Nearctic, which can be explained by the higher aquatic habitat diversity at micro and macroscales east of the Rocky Mountains, promoting niche partitioning and specialization. In the Nearctic region, the southeastern US has the highest number of endemic species of dragonflies and damselflies; this degree of endemism is likely due to glacial refuges providing a foundation for the evolution of a rich and unique biota.