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

Abstract

Background 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 due to overestimation of the potential for trait reacquisition as well as to the lack of taxonomic data. Results We revisited 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 euphasmatodean lineage. Conclusion In this study, we explored the evolutionary history of wings in Phasmatodea and demonstrate that the disjunct distribution of ocelli substantiates the hypothesis on their regain and thus on trait reacquisition in general. Evidence from the fossil record as well as future studies focussing on the underlying genetic mechanisms are needed to validate our findings and to further assess the evolutionary process of phenotypic reversals.

Permian parallelisms: Reanalysis of †Tshekardocoleidae sheds light on the earliest evolution of the Coleoptera

“…The most extreme cases are the cuticular tubercles on the body dorsum (C3) and abdominal ventrites (C4), which are gained, lost and regained under the “extant tree” constraint. The information for this particular transition series is lost, however, when †Permocupedidae are deleted, as this family is consistently recovered as the sister group to all other Coleoptera to the exclusion of †Tshekardocoleidae. When †Tshekardocoleidae is deleted, transitional information for seven coleopteran apomorphies is lost (Bank & Bradler, 2022; Beutel et al, 2008; Feng et al, 2017; Forbes, 1928; Goloboff et al, 2008; Kirejtshuk, 2020; Kukalová‐Peck & Beutel, 2012) (Figure 2d). Specifically, † Tshekardocoleidae have the following: abdominal ventrites that are capable of telescoping (C2), tectiform (tent‐like) elytra (C6:0), fore‐ and hindwings of equal length (C26), the katepisternal mesocoxal joint (C28), no elytral epipleurae (C32), and hindwings without transverse folding (C43).…”

“…2. When †Tshekardocoleidae is deleted, transitional information for seven coleopteran apomorphies is lost (Bank & Bradler, 2022;Beutel et al, 2008;Feng et al, 2017;Forbes, 1928;Goloboff et al, 2008;Kirejtshuk, 2020;Kukalová-Peck & Beutel, 2012) (Figure 2d). Specifically, † Tshekardocoleidae have the following:…”

Convergent Evolution of Adhesive Properties in Leaf Insect Eggs and Plant Seeds: Cross-Kingdom Bioinspiration

“…Furthermore, other eggs of several unrelated phasmids also carry glue [ 26 ], and some seem to represent similar non-permanent water-responsive adhesive mechanisms [ 68 ]. The evolution of such egg surface structures and adhesive systems on eggs is likely a similar complex evolutionary scenario, comparable to other aspects of phasmatodean evolution [ 69 , 70 ], such as the tarsal adhesive systems. These also result from complex environmental conditions and are shaped by interactions with various substrates [ 7 , 71 , 72 , 73 , 74 , 75 ].…”

Beyond winglets: evolutionary scaling of flight-related morphology in stick insects (Phasmatodea)

“…4A ). This variability in number may be regulated as developmental duplication, and could contribute to relatively rapid evolution of wing gain or reduction in phasmids (Zeng et al, 2020; Bank and Bradler, 2022). Although not analyzed here, miniaturized wings of Q < 0.3 seem to possess high variability in design and functionality ( Fig.…”