Integrated phylogenomic and fossil evidence of stick and leaf insects (Phasmatodea) reveal a Permian–Triassic co-origination with insectivores

Abstract

Stick and leaf insects (Phasmatodea) are a distinctive insect order whose members are characterized by mimicking various plant tissues such as twigs, foliage and bark. Unfortunately, the phylogenetic relationships among phasmatodean subfamilies and the timescale of their evolution remain uncertain. Recent molecular clock analyses have suggested a Cretaceous–Palaeogene origin of crown Phasmatodea and a subsequent Cenozoic radiation, contrasting with fossil evidence. Here, we analysed transcriptomic data from a broad diversity of phasmatodeans and, combined with the assembly of a new suite of fossil calibrations, we elucidate the evolutionary history of stick and leaf insects. Our results differ from recent studies in the position of the leaf insects (Phylliinae), which are recovered as sister to a clade comprising Clitumninae, Lancerocercata, Lonchodinae, Necrosciinae and Xenophasmina . We recover a Permian to Triassic origin of crown Phasmatodea coinciding with the radiation of early insectivorous parareptiles, amphibians and synapsids. Aschiphasmatinae and Neophasmatodea diverged in the Jurassic–Early Cretaceous. A second spur in origination occurred in the Late Cretaceous, coinciding with the Cretaceous Terrestrial Revolution, and was probably driven by visual predators such as stem birds (Enantiornithes) and the radiation of angiosperms.

Reconstructing the nonadaptive radiation of an ancient lineage of ground‐dwelling stick insects (Phasmatodea: Heteropterygidae)

“…These were however recently challenged by Tihelka et al . (2020), who proposed a significantly older origin – an age that cannot to be satisfactorily determined from the data they provided but which we assume to be approximately 90 mya for this clade (misspelled by the authors as ‘Heteropterygida’). This discrepancy can be partly explained by the usage of different sets of fossils as calibration points.…”

“…Tihelka et al . (2020) included fossils that were intentionally excluded in the study by Robertson et al . (2018), such as Echinosomiscus primoticus Engel & Wang, a fossil insect preserved in Cretaceous amber (∼99 mya) described as an adult male related to a subordinate lineage comprising Lonchodinae and Clitumninae (Engel et al ., 2016).…”

“…Another important fossil specimen included by Tihelka et al . (2020) is a Jurassic heelwalker (Mantophasmatodea) described by Huang et al . (2008) that needs to be critically reassessed.…”

Phylogenomic subsampling and the search for phylogenetically reliable loci

“…Phylogenetic inference using subsampled datasets was performed using IQ-TREE 1.6.3 (Nguyen, et al 2014) under the LG+F+G model, and node support was estimated using 1,000 replicates of ultrafast bootstrap (UFBoot; Hoang, et al 2017). Characterizing the performance of these datasets is complicated by the fact that the underlying phylogenies are unknown (in fact some of the trees used here have already been challenged to some degree; see Meusemann, et al 2020;Szucsich, et al 2020;Tihelka, et al 2020).…”

Beyond Congruence: Evidential Integration and Inferring the Best Evolutionary Scenario

“…Phylogenetics, or genealogical systematics, has been transformed in recent decades by the advent of molecular approaches to classification relying on similarities in the genetic material of living taxa; starting with analyses on small sets of genes, they have come a long way to the large-scale phylogenomics of recent years [1][2][3][4][5][6][7][8][9], often calibrated by fossils [10,11]. The impact of molecular approaches to phylogenetics cannot be understated: we now have access to an unprecedented wealth of data from a wide variety of organisms independent of morphological data, and a panoply of sophisticated analytical tools enabling their interpretation.…”