A second view on the evolution of flight in stick and leaf insects (Phasmatodea)

Abstract

The re-evolution of complex characters is generally considered impossible, yet, studies of recent years have provided several examples of phenotypic reversals shown to violate Dollo's law. Along these lines, the regain of wings in stick and leaf insects (Phasmatodea) was hypothesised to have occurred several times independently after an ancestral loss, a scenario controversially discussed among evolutionary biologists. Here, we revisit the recovery of wings by reconstructing a phylogeny based on a comprehensive taxon sample of over 500 representative phasmatodean species to infer the evolutionary history of wings. We additionally explored the presence of ocelli, the photoreceptive organs used for flight stabilisation in winged insects, which might provide further information for interpreting flight evolution. Our findings support an ancestral loss of wings and that the ancestors of most major lineages were wingless. While the evolution of ocelli was estimated to be dependent on the presence of (fully-developed) wings, ocelli are nevertheless absent in the majority of all examined winged species and only appear in the members of few subordinate clades, albeit winged and volant taxa are found in every lineage. The disjunct distribution of ocelli substantiates the hypothesis on trait reacquisition and that wings were regained in Phasmatodea.

Two new stick insect species of Sosibia Stål (Phasmatodea: Lonchodidae: Necrosciinae) from China and the first report on mitochondrial genomes of this genus

“…In this study, Sosibia and Calvisia are sister groups and form a clade with Sipyloidea while Neohirasea and Micadina form another clade. Multiple mitochondrial and nuclear gene fragments and samples from more genera support the idea that the two clades are contained in Necrosciinae (Bank & Bradler, 2021; Bradler et al, 2014; Goldberg et al, 2015). Meanwhile, Sipyloidea and Neohirasea always belong to different clades.…”

“…Multiple mitochondrial and nuclear gene fragments and samples from more genera support the idea that the two clades are contained in Necrosciinae (Bank & Bradler, 2021;Bradler et al, 2014;Goldberg et al, 2015). Meanwhile,…”