A Jurassic Gondwanan origin with a Mesozoic vicariance and Cenozoic dispersals explains the biogeographic history of crown webspinners (Insecta: Embioptera)

Abstract Embioptera, commonly called webspinners, represent a small and understudied order of insects whose evolutionary history is poorly understood. To date, neither the timing of their origin, diversification, nor biogeographic history has been thoroughly investigated. In this study, we establish the groundwork for addressing these gaps by estimating divergence times for most extant webspinner lineages and reconstructing their biogeographic history using molecular and morphological datasets. Regardless of the sampling fractions (representing either the current or estimated diversity of webspinners), the clock models, and the inclusion or exclusion of morphological data, our divergence time estimates indicated that webspinners originated at around 280 Mya in the Permian, whereas the crown Embioptera appeared later, around 170 Mya in the Middle Jurassic. Our sensitivity analyses indicated that the divergence time estimates were robust to known biases in molecular dating analyses. With this new time-calibrated phylogenetic framework, we investigated the ancestral geographic origin of the order and reconstructed the historical biogeography of webspinners. Our analyses confirmed the expected Gondwanan origin of the crown group evident in the distribution of extant families, and a first radiation in Australia (Australembiidae). Our results suggested that the distribution of extant Embioptera results from a combination of vicariance, due to the break-up of Gondwana, and dispersal events following continental collisions during the Cenozoic. Through our analyses, we present a first comprehensive scenario for the diversification and origin of Embioptera, which provides testable hypotheses for further studies.