BUTTERFLIES, BUGS AND MOSQUITOES ARE OLDER THAN PREVIOUSLY THOUGHT

7 November 20197 November 2019 Domenico Ditto

The 9th October 2019 the Proceedings of the Royal Society B: Biological Sciences journal published a study where new dates for the evolution of insects were estimated and the End-Permian mass extinction event resulted to have a limited impact on the evolution of these organisms. The study has been carried out by Matteo Montagna and Giulia Magoga, entomologists at the Department of Agriculture and Environmental Sciences – Università degli Studi di Milano, in collaboration with a group of expert palaeontologists and evolutionary biologists, Andrea Tintori and Laura Strada (Università degli Studi di Milano) and Nathan Lo, Jun Tong, Simon Ho (University of Sidney). In this study, the genomic data of 140 arthropods species, mainly insects, joined to the dating obtained from eight exceptionally preserved insects fossils found in the UNESCO site of Monte San Giorgio, allowed to infer new estimates on the origin of different insects groups and evaluate the impact of the End-Permian mass crisis on these organisms. The obtained results show that many groups, among which Lepidoptera, Hemiptera Heteroptera and Diptera, appeared much sooner than was thought; their origin resulted prior to the End-Permian mass crisis, indicating that the impact of this event, that for some organisms was catastrophic, had not strongly influenced insects evolution and the appearance of modern fauna. Moreover, innovations as the evolution of wings or the complete metamorphosis, considered key innovations in the evolution of this group, resulted older than previously thought. The findings of this study should be considered of crucial importance since providing new information necessary for the understanding of insects evolution, the organisms dominating continental ecosystems.

Figure: dated phylogenetic tree of Hexapods, inferred from a dataset of 220.615 Amino Acids and dated using 35 fossils (eight found in Monte San Giorgio; their position is indicated by stars). Above the nodes 95% dating confidence intervals, in red those for which the estimate is backdated of more then 50 million years in respect to previous studies.

REFERENCE

Montagna M, Tong KJ, Magoga G, Strada L, Tintori A, Ho SYW, Lo N. Recalibration of the insect evolutionary time scale using Monte San Giorgio fossils suggests survival of key lineages through the End-Permian Extinction. Proc Biol Sci. 2019 Oct 9;286(1912):20191854. DOI: 10.1098/rspb.2019.1854.