Diversification and evolution of Hawaiian Megalagrion damselflies (Pinapinao, Odonata: Coenagrionidae)

Hawaiʻi’s pinapinao (Megalagrion McLachlan) comprises a radiation of 23
endemic damselfly species within Coenagrionidae. Despite being a unique
study system for understanding geology’s impacts on evolutionary processes
among Odonata, the understanding of these damselflies’ temporal,
geographic, and phylogenetic origins remains incomplete. Testing
macroevolutionary hypotheses has been hampered by conflicting topologies.
To resolve these uncertainties, we performed phylogenetic analyses
including divergence time estimation with 90 nuclear loci (>50 kbp)
and 2 mitochondrial loci (>1 kbp), sampling representatives from 37
genera within core Coenagrionidae and 90% of Megalagrion species,
including multiple island populations. We used ancestral range
estimations, diversification analyses, agent-based simulation modeling,
and ancestral state reconstruction to infer the group’s origin and
biogeography and assess traits’ roles in diversification. Our findings
indicate Megalagrion’s ancestor diverged from core Coenagrionidae early
Eocene (~51 MA) and diversified early Miocene (~19 MA), suggesting
Megalagrion’s MRCA predates Kauaʻi’s emergence by 7–21 MY. Diversification
analyses suggest a low rate after Megalagrion diverged from
Coenagrionidae, followed by a sudden increase around 19 MA, and simulation
modeling supports extinction playing a significant role. Extant
Megalagrion diversity is largely explained by ecological diversification
into at least five clades with distinct breeding habitats that likely
evolved on the Northwestern Hawaiian Islands, which are now sunken
seamounts. Speciation continued as descendants dispersed to the current
Hawaiian Islands as islands emerged. Species breeding in seeps further
diversified within the island of Kauaʻi. Our results highlight including
geologic changes over time in evolutionary studies and increase
understanding of diversification patterns, biogeography, and adaptive
radiation on islands. This dataset contains scripts, data, and files used
to perform the study described above and published in the article
"Diversification and Evolution of Hawaiian Megalagrion Damselflies
(Pinapinao, Odonata: Coenagrionidae)" in Systematic Entomology.