https://www.researchgate.net/profile/Bonnie-Blaimer

Why are some insect groups more diverse than others? Remarkable morphological features and behavioral innovations that confer a selective advantage to their bearers have often been linked to species diversification, yet the relative importance of different traits and the methods used to detect their effects remain debated. In this talk, I explore how form, function, and phylogeny intersect to shape diversification patterns across Hymenoptera, from order-wide macroevolutionary dynamics to genus-level color evolution. First, using a comprehensive genomic-scale phylogeny of Hymenoptera, I investigate whether potential key innovations have influenced diversification across the order: the wasp waist of Apocrita; the stinger of Aculeata; parasitoidism, a specialized form of carnivory; and secondary phytophagy, a reversal to plant-feeding. I show that although parasitoidism has been the dominant strategy since the Late Triassic, transitions to secondary phytophagy had the most significant influence on diversification rate. Second, I zoom in on the large carpenter bees (genus Xylocopa), a diverse, globally distributed clade exhibiting reversed sexual dichromatism and conspicuous aposematic coloration. Using phylogenomics to estimate a species-level phylogeny, I reconstruct the evolution of color patterns across the genus. A monochromatic, inconspicuous ancestor is inferred, with subsequent convergent evolution of sexual dichromatism and aposematism in multiple lineages. Trait-dependent diversification analyses yield contradicting results regarding the role of color evolution in driving speciation, highlighting methodological challenges in linking phenotypic traits to diversification dynamics. Collectively, these case studies illustrate how morphological and behavioral traits can shape diversification at different phylogenetic scales, and underscore the need for integrative approaches when testing key innovation hypotheses in hyperdiverse insect clades.

https://romainpboisseau.github.io/

The observation of repeatability in phenotypic evolution across taxa suggests that, at least sometimes, evolution may be forecasted. Yet it is still unclear what factors determine the level of repeatability of evolutionary outcomes and trajectories. If independent lineages are subjected to the same environmental challenges, what influences how often they evolve the same phenotypes? When does repeatability break down? One possibility is the actual degree of environmental similarity, and therefore the extent to which selective regimes truly are alike between independent lineages occupying seemingly identical niches. Another is the genetic distance between lineages: closely related lineages share more standing genetic variation, genetic background and developmental mechanisms, and are therefore expected to respond in a more analogous way to similar selective regimes. We tested these two factors using stick and leaf insects (order Phasmatodea), a group in which many lineages have repeatedly transitioned to similar habitats. Phasmids are renowned for their extraordinary morphological diversity associated with camouflage, ranging from elongated branch mimics to wide and flattened leaf mimics. We focused on female morphology, measuring 212 species spanning all major clades and combining these data with a robust phylogenetic reconstruction. We show that when transitioning to the same habitat, lineages that are more closely related and that experience more similar environmental conditions end up displaying more similar morphologies, and that more closely related lineages also follow more parallel trajectories through morphospace. Repeatability decreases at a relatively constant rate across more than 100 My of divergence, suggesting that even the magnitude of contingency can be predictable, given sufficient spans of time. We then turn to sexual dimorphism, which, unlike female body morphology, is not an individual-level phenotype but a species-level trait: no individual expresses it and selection can reach it only indirectly through each sex. Where a given female morphology corresponds to a single phenotype, a given degree of dimorphism can be reached by many combinations of male and female forms — so lineages constrained to different parts of morphospace may nonetheless arrive at the same outcome. Extending the morphospace to males lets us ask a simple question: do more distantly related lineages still converge less, even for a phenotype that offers many routes to the same outcome?

https://www.nhm.ac.uk/our-science/people/greg-edgecombe.html

The interrelationships of the five living orders of centipedes (Myriapoda: Chilopoda) have received a nearly universal consensus from the perspective of morphology for decades; the early years of centipede molecular phylogenetics were effectively a test of the efficacy of the then-used markers to reconstruct phylogeny. As gene sampling grew, incongruence between morphological and molecular datasets emerged with respect to the placement of one low diversity relictual clade. Transcriptomic datasets analysed under conditions designed to minimise systematic error have consistently recovered the two species of Craterostigmus/Craterostigmomorpha in a position that, if accurate, implies homoplasy in a suite of external morphological, internal anatomical and behavioural characters that cannot readily be ascribed to functional interdependence.  The morphological unexpectedness of this result and the persistent possibility that long branch attraction to the basally branching Scutigeromorpha draws Craterostigmus stemward have prompted alternative molecular datasets and different models for total evidence phylogenetics. A new myriapod probe set for ultraconserved elements (UCEs) guided by new genomes yields trees with consistently strong support for early divergence of Craterostigmus, reinforcing the Sanger and transcriptomic results. A tip-dated tree under the Fossilized Birth-Death model, including 11 fossil centipedes spanning the Early Devonian to Miocene, >470 morphological characters, and three loci for >370 extant species, offers a solution anticipated by neither molecular nor morphological datasets in isolation. The prevalent notion that morphology must be misleading in instances of molecular consensus should not be accepted uncritically; the centipede example is a “perfect storm” for any dataset, with early branching lineages having long stems and shallow crowns, few extant taxa left unsampled, and high rates of extinction with low rates of diversification. Incongruence between morphological and phylogenomic trees for the four classes of myriapods is informed by a quartet-based approach, with transcriptomes and UCEs both selecting a hypothesis supported by morphology and development (Progoneata) as well as one that is principally molecular (Edafopoda).

Jendrian Riedel et al. – Evolution of incipient toepads in a radiation of ecologically diverse geckos

Adhesive toepads have evolved repeatedly in a variety of clades thereby facilitating attachment to inclined surfaces in climbing species. Among vertebrates, geckos are the most thoroughly studied with regard to their adhesive toepads. Even so, the evolutionary origin of these complex structures is still elusive, this being partially due to the scarcity of studies on species with incipiently developed toepad morphologies. One suggested model for the presence of incipient toepads are the bent-toed geckos (genus Cyrtodactylus), an ecologically diverse radiation, the climbing members of which possess enlarged subdigital scales. It is known that a few such species carry spatulated setae as the microstructures on these scales. Given this, we explore the evolution of incipient toepad morphology in Cyrtodactylus species from different microhabitats (ecotypes) in relation to habitat use (terrestrial, arboreal, rock-dwelling and generalist) to unravel how and under what ecological circumstances adhesive toepads evolved. We measured size-corrected subdigital scale area, examined subdigital scale shape using 2D geometric morphometrics, and subdigital microstructures using scanning electron microscopy. We reconstructed the evolution of these traits and tested whether species occupying different microhabitats differed in their subdigital scale morphology. We found that both arboreal and rock-dwelling species had relatively larger subdigital scale areas compared to terrestrial and generalist species, with subdigital scales that incrementally approach the shape of typical adhesive pads. Microstructures, to the contrary, are more phylogenetically clustered than ecologically correlated.

Benjamin Wipfler – Evolutionary morphology of Polyneoptera 

Polyneoptera constitutes one of the major lineages of winged insects and comprises 11 traditional orders, including cockroaches (Blattodea), earwigs (Dermaptera), grasshoppers, crickets and allies (Orthoptera), and stoneflies (Plecoptera). However, the phylogenetic relationships among these orders have long remained poorly resolved, strongly impeding our understanding of the biology and evolutionary history of the entire group. By combining molecular and morphological evidence, we developed a well-supported working hypothesis for polyneopteran phylogeny. In combination with morphological and palaeontological data, this phylogenetic framework allows us to reconstruct the evolutionary history of Polyneoptera and to trace the major adaptations that shaped the diversification of the clade. Our results suggest that Polyneoptera originated approximately 320 million years ago and rapidly became one of the most successful lineages of insects, comprising more than 50% of all insect families. The last common ancestor of Polyneoptera was apparently strongly adapted to a ground-dwelling lifestyle and showed features such as hardened forewings and a dorsoventrally flattened body, patterns that are still present in many extant lineages. However, several subgroups, including stick and leaf insects (Phasmatodea) and heelwalkers (Mantophasmatodea), secondarily shifted towards a lifestyle in the foliage, resulting in extensive morphological adaptations associated with this habitat. Polyneoptera was strongly affected by multiple extinction events at the end of the Palaeozoic, during which several lineages became extinct. The group apparently never fully recovered from these events, and during the Triassic, both Holometabola and Paraneoptera surpassed Polyneoptera in terms of family-level diversity.

Thies Büscher et al. – Evolution of functional surface microstructures on leaf insect eggs (Phasmatodea: Phylliidae)

Leaf insects (Phylliidae) are herbivorous being famous for exhibiting impressive cryptic masquerade. They almost perfectly imitate angiosperm leaves and their eggs often resemble plant seeds. While adult Phylliidae are morphologically very similar, their eggs reveal a significant diversity in overall shape and exochorionic surface features. Previous studies have documented the specialised attachment mechanism of one species with hierarchical exochorionic fan-like structures (pinnae), which are mantled by a film of an adhesive secretion (glue). The folded pinnae and glue respond to water contact, with the fibrous pinnae expanding and the glue being capable of reversible liquefaction. In general, the eggs of phylliids appear to exhibit varying surface structures that were suggested to represent specific adaptations to different environments the eggs are exposed to. Here, we investigated the diversity of phylliid eggs and the functional morphology of their exochorionic structures. Based on the examination of all known eggs of phylliids, we characterised eleven different morphological types. We explored the adhesiveness of these morphotypes and experimentally compared the attachment performance on a broad range of substrates with different surface roughness, surface chemistry and tested whether the adhesion is replicable after detachment in multiple cycles. Furthermore, we used molecular phylogenetic methods to reconstruct the evolutionary history of different egg types and their adhesive systems within this lineage. Our results suggest that the egg morphology is congruent with the phylogenetic relationships within Phylliidae. The morphological differences are likely caused by adaptations to the specific environmental requirements for the particular clades, as the egg morphology has an influence on the performance regarding the surface roughness. Furthermore, we show that different pinnae types and the adhesive glue evolved convergently in different species. While the evolution of the Phylliidae in general appears to be non-adaptive judging on the strong similarity of the adults and nymphs of most species, the eggs represent a stage with complex and rather diverse functional adaptations including mechanisms for both fixation and dispersal of the eggs.

Stefan Reif et al. – Morphological comparison of the modified haemolymph pressure pump between juveniles and adults of Perania nasuta (Araneae: Pacullidae)

In Araneae (spiders), leg extension is caused by an increase in haemolymph pressure, which compensates for the lack of extensor muscles in two key joints. In the ground pattern of Araneae, contraction of prosomal dorso-ventral muscles compresses the prosoma in the region of the flexible pleural membrane. A number of araneaen taxa, such as Pacullidae, are characterised by adult stages with fully sclerotised pleurae that connect the tergum and sternum immovably, which renders compression impossible. Adult Perania nasuta (Pacullidae) exhibit external modifications in the opisthosoma, including sclerotised dorsal and ventral plates, as well as smaller sclerites within the soft lateral cuticle. Internally, these sclerotised areas are connected by a laterally concentrated and well-developed opisthosomal muscle sac. This suggests that the generation of haemolymph pressure has shifted to the opisthosoma, where it is produced by contraction of the opisthosomal muscle sac. Juveniles differ from adults in their sclerotisation pattern. Externally, juveniles exhibit less distinct opisthosomal sclerites, and the extension of sclerotisation of the prosomal pleura is incomplete. This raises the question of whether there are differences in muscle composition that account for haemolymph pressure generation between juveniles and adults. We investigated the skeletomuscular system of juveniles using micro-computed tomography. We provide detailed 3D reconstructions of both tagmata to demonstrate morphological differences between juveniles and adults to draw conclusions on functional consequences.

Ben Zechiel & Margarita Yavorskaya – Morphological transformations of the abdominal base in ant-like litter beetles (Coleoptera: Staphylinidae: Pselaphinae)

With around 10,000 described species the cosmopolitan Pselaphinae comprise the second largest subfamily of Staphylinidae. An extreme structural reorganization and variability of all body regions occurs in Pselaphinae, leading to an extraordinary morphological diversity. This fascinating diversity is still scarcely understood. One of the reasons for many morphological transformations in Pselaphinae could be close association with ants, with myrmecophily evolving in multiple pselaphine lineages. Many changes have occurred to the abdominal base (first three abdominal segments) of Pselaphinae, however, this body region remains understudied in Staphylinidae. The aim of our study was to explore unique morphological transformations in the abdominal base of Pselaphinae. SRµCT was used to create 3D reconstructions of the abdominal base of five myrmecophile and non-myrmecophile pselaphine species from different lineages and three outgroup species, including the rare representative of the sister group of Pselaphinae, Protopselaphus. Differences between the species in the compactness of the abdominal base were detected. Several external and internal structures were found that show a strong variability in Pselaphinae. Our findings suggest that Pselaphinae have a less flexible and more rigid abdomen than non-pselaphine staphylinids. Furthermore, two apomorphies in the abdominal base of Pselaphinae were detected: the fusion of the median carinae of sternite II and sternite III and the presence of internal dorsolateral processes in sternite III. We also show differences in the structure of sternite III for the examined myrmecophilous species: dorsolateral processes are stronger developed and closer connected to the endoskeletal elements of the tergite, probably to provide additional stability. Our study shows that multiple structural transformations have occurred to the abdominal base of Pselaphinae, reducing the flexibility and increasing the stability of the abdomen in this remarkable subgroup of rove beetles.