A macroevolutionary role for chromosomal fusion and fission in Erebia butterflies.

The impact of large-scale chromosomal rearrangements, such as fusions and fissions, on speciation is a long-standing conundrum. We assessed whether bursts of change in chromosome numbers resulting from chromosomal fusion or fission are related to increased speciation rates in Erebia, one of the most species-rich and karyotypically variable butterfly groups. We established a genome-based phylogeny and used state-dependent birth-death models to infer trajectories of karyotype evolution. We demonstrated that rates of anagenetic chromosomal changes (i.e., along phylogenetic branches) exceed cladogenetic changes (i.e., at speciation events), but, when cladogenetic changes occur, they are mostly associated with chromosomal fissions rather than fusions. We found that the relative importance of fusion and fission differs among Erebia clades of different ages and that especially in younger, more karyotypically diverse clades, speciation is more frequently associated with cladogenetic chromosomal changes. Overall, our results imply that chromosomal fusions and fissions have contrasting macroevolutionary roles and that large-scale chromosomal rearrangements are associated with bursts of species diversification.

Impact of increasing morphological information by micro-CT scanning on the phylogenetic placement of Darwin wasps (Hymenoptera, Ichneumonidae) in amber.

The correct interpretation of fossils and their reliable taxonomic placements are fundamental for understanding the evolutionary history of biodiversity. Amber inclusions often preserve more morphological information than compression fossils, but are often partially hidden or distorted, which can impede taxonomic identification. Here, we studied four new fossil species of Darwin wasps from Baltic and Dominican amber, using micro computed tomography (micro-CT) scans and 3D reconstructions to accurately interpret and increase the availability of morphological information. We then infer their taxonomic placement in a Bayesian phylogenetic analysis by combining morphological and molecular data of extant and fossil Darwin wasps and evaluate the impact and usefulness of the additional information from micro-CT scanning. The results show that although we gained significant morphological information from micro-CT scanning, especially concerning measurements and hidden dorsal and ventral structures, this did not impact subfamily-level placement for any of the four fossils. However, micro-CT scanning improved the precision of fossil placements at the genus level, which might be key in future dating and diversification analyses. Finally, we describe the four new fossil species as Rhyssa gulliveri sp. nov. in Rhyssinae, Triclistus levii sp. nov. in Metopiinae, Firkantus freddykruegeri gen. et. sp. nov. in Pimplinae and Magnocula sarcophaga gen. et sp. nov. in Phygadeuontinae. The first two species are the first known representatives of the subfamilies Rhyssinae and Metopiinae in amber. Supplementary Information: The online version contains supplementary material available at 10.1186/s13358-023-00294-2.

Classifying fossil Darwin wasps (Hymenoptera: Ichneumonidae) with geometric morphometrics of fore wings.

Linking fossil species to the extant diversity is often a difficult task, and the correct interpretation of character evidence is crucial for assessing their taxonomic placement. Here, we make use of geometric morphometrics of fore wings to help classify five fossil Darwin wasps from the Early Eocene Fur Formation in Denmark into subfamilies and often tribes. We compile a reference dataset with 342 fore wings of nine extant subfamilies and nine relevant fossil species. Since geometric morphometrics was mostly ignored in the past in Darwin wasp classification, the dataset is first used to examine differences and similarities in wing venation among subfamilies. In a next step, we used the reference dataset to inform the classification of the fossil species, which resulted in the description of one new genus and five new species, Crusopimpla weltii sp. nov., Ebriosa flava gen. et sp. nov., Entypoma? duergari sp. nov., Lathrolestes? zlatorog sp. nov., and Triclistus bibori sp. nov., in four different subfamilies. Carefully assessing data quality, we show that the fore wing venation of fossil Darwin wasps is surprisingly suitable to assign them to a subfamily or even lower taxonomic level, especially when used in conjunction with characters from other parts of the body to narrow down a candidate set of potential subfamilies and tribes. Our results not only demonstrate a fast and useful approach to inform fossil classification but provide a basis for future investigations into evolutionary changes in fore wings of ichneumonids. The high informativeness of wing venation for classification furthermore could be harvested for phylogenetic analyses, which are otherwise often hampered by homoplasy in this parasitoid wasp family.

Many evolutionary roads led to virus domestication in ichneumonoid parasitoid wasps.

The investigation of endogenous viral elements (EVEs) has historically focused on only a few lineages of parasitoid wasps, with negative results consistently underreported. Recent studies show that multiple viral lineages were integrated in at least seven instances in Ichneumonoidea and may be much more widespread than previously thought. Increasingly affordable genomic and bioinformatic approaches have made it feasible to search for viral sequences within wasp genomes, opening an extremely promising research avenue. Advances in wasp phylogenetics have shed light on the evolutionary history of EVE integration, although many questions remain. Phylogenetic proximity can be used as a guide to facilitate targeted screening, to estimate the number and age of integration events and to identify taxa involved in major host switches.

Incongruent molecular and morphological variation in the crab spider Synemaglobosum (Araneae, Thomisidae) in Europe.

Establishing species boundaries is one of the challenges taxonomists around the world have been tackling for centuries. The relation between intraspecific and interspecific variability is still under discussion and in many taxa it remains understudied. Here the hypothesis of single versus multiple species of the crab spider Synemaglobosum (Fabricius) is tested. The wide distribution range as well as its high morphological variability makes this species an interesting candidate for re-evaluation using an integrative approach. This study combines information from barcoding, phylogenetic reconstruction based on mitochondrial CO1 and ITS2 of more than 60 specimens collected over a wide range of European localities, and morphology. The findings show deep clades with up to 6% mean pairwise distance in the CO1 barcode without any biogeographical pattern. The nuclear ITS2 gene did not support the CO1 clades. Morphological assessment of somatic and genital characters in males and females and a morphometric analysis of the male palp uncovered high intraspecific variation that does not match the CO1 or ITS2 phylogenies or biogeography either. Screening for endosymbiotic Wolbachia bacteria was conducted and only a single infected specimen was found. Several scenarios might explain these inconsistent patterns. While the deep divergences in the barcoding marker might suggest cryptic or ongoing speciation or geographical isolation in the past, the lack of congruent variation in the nuclear ITS2 gene or the studied morphological character systems, especially the male palp, indicates that S.globosum might simply be highly polymorphic both in terms of its mtDNA and morphology. Therefore, more data on ecology and behaviour and full genome sequences are necessary to ultimately resolve this taxonomically intriguing case.

Mind the Outgroup and Bare Branches in Total-Evidence Dating: a Case Study of Pimpliform Darwin Wasps (Hymenoptera, Ichneumonidae).

Taxon sampling is a central aspect of phylogenetic study design, but it has received limited attention in the context of total-evidence dating, a widely used dating approach that directly integrates molecular and morphological information from extant and fossil taxa. We here assess the impact of commonly employed outgroup sampling schemes and missing morphological data in extant taxa on age estimates in a total-evidence dating analysis under the uniform tree prior. Our study group is Pimpliformes, a highly diverse, rapidly radiating group of parasitoid wasps of the family Ichneumonidae. We analyze a data set comprising 201 extant and 79 fossil taxa, including the oldest fossils of the family from the Early Cretaceous and the first unequivocal representatives of extant subfamilies from the mid-Paleogene. Based on newly compiled molecular data from ten nuclear genes and a morphological matrix that includes 222 characters, we show that age estimates become both older and less precise with the inclusion of more distant and more poorly sampled outgroups. These outgroups not only lack morphological and temporal information but also sit on long terminal branches and considerably increase the evolutionary rate heterogeneity. In addition, we discover an artifact that might be detrimental for total-evidence dating: "bare-branch attraction," namely high attachment probabilities of certain fossils to terminal branches for which morphological data are missing. Using computer simulations, we confirm the generality of this phenomenon and show that a large phylogenetic distance to any of the extant taxa, rather than just older age, increases the risk of a fossil being misplaced due to bare-branch attraction. After restricting outgroup sampling and adding morphological data for the previously attracting, bare branches, we recover a Jurassic origin for Pimpliformes and Ichneumonidae. This first age estimate for the group not only suggests an older origin than previously thought but also that diversification of the crown group happened well before the Cretaceous-Paleogene boundary. Our case study demonstrates that in order to obtain robust age estimates, total-evidence dating studies need to be based on a thorough and balanced sampling of both extant and fossil taxa, with the aim of minimizing evolutionary rate heterogeneity and missing morphological information. [Bare-branch attraction; ichneumonids; fossils; morphological matrix; phylogeny; RoguePlots.].

Completing Linnaeus's inventory of the Swedish insect fauna: Only 5,000 species left?

Despite more than 250 years of taxonomic research, we still have only a vague idea about the true size and composition of the faunas and floras of the planet. Many biodiversity inventories provide limited insight because they focus on a small taxonomic subsample or a tiny geographic area. Here, we report on the size and composition of the Swedish insect fauna, thought to represent roughly half of the diversity of multicellular life in one of the largest European countries. Our results are based on more than a decade of data from the Swedish Taxonomy Initiative and its massive inventory of the country's insect fauna, the Swedish Malaise Trap Project The fauna is considered one of the best known in the world, but the initiative has nevertheless revealed a surprising amount of hidden diversity: more than 3,000 new species (301 new to science) have been documented so far. Here, we use three independent methods to analyze the true size and composition of the fauna at the family or subfamily level: (1) assessments by experts who have been working on the most poorly known groups in the fauna; (2) estimates based on the proportion of new species discovered in the Malaise trap inventory; and (3) extrapolations based on species abundance and incidence data from the inventory. For the last method, we develop a new estimator, the combined non-parametric estimator, which we show is less sensitive to poor coverage of the species pool than other popular estimators. The three methods converge on similar estimates of the size and composition of the fauna, suggesting that it comprises around 33,000 species. Of those, 8,600 (26%) were unknown at the start of the inventory and 5,000 (15%) still await discovery. We analyze the taxonomic and ecological composition of the estimated fauna, and show that most of the new species belong to Hymenoptera and Diptera groups that are decomposers or parasitoids. Thus, current knowledge of the Swedish insect fauna is strongly biased taxonomically and ecologically, and we show that similar but even stronger biases have distorted our understanding of the fauna in the past. We analyze latitudinal gradients in the size and composition of known European insect faunas and show that several of the patterns contradict the Swedish data, presumably due to similar knowledge biases. Addressing these biases is critical in understanding insect biomes and the ecosystem services they provide. Our results emphasize the need to broaden the taxonomic scope of current insect monitoring efforts, a task that is all the more urgent as recent studies indicate a possible worldwide decline in insect faunas.

Illustrating phylogenetic placement of fossils using RoguePlots: An example from ichneumonid parasitoid wasps (Hymenoptera, Ichneumonidae) and an extensive morphological matrix.

The fossil record constitutes the primary source of information about the evolutionary history of extant and extinct groups, and many analyses of macroevolution rely on fossils that are accurately placed within phylogenies. To avoid misinterpretation of the fossil record, especially by non-palaeontologists, the proper assessment and communication of uncertainty in fossil placement is crucial. We here use Bayesian morphological phylogenetics to evaluate the classifications of fossil parasitoid wasps (Hymenoptera, Ichneumonidae) and introduce 'RoguePlots' to illustrate placement uncertainty on the phylogeny of extant taxa. Based on an extensive, newly constructed morphological matrix of 222 characters in 24 fossil and 103 extant taxa, we test three different aspects of models of morphological evolution. We find that a model that includes ordered characters, among-character rate variation, and a state-space restricted to observed states achieves the highest marginal likelihoods. The individual RoguePlots reveal large differences in confidence in the placement of the different fossils and allow some refinements to their classification: Polyhelictes bipolarus and Ichninsum appendicrassum are moved from an uncertain subfamily placement to Pimplinae, Plectiscidea lanhami is transferred to Allomacrus in Cylloceriinae (Allomacrus lanhami, comb. nov.), Lithotorus cressoni is moved from Diplazontinae to Orthocentrinae, and we note uncertainty in the generic placements of Rhyssella? vera and Xanthopimpla? messelensis. We discuss potential artefacts that might result in biased posterior probabilities in Bayesian morphological phylogenetic analyses, pertaining to character and taxon sampling, fossilization biases, and model misspecification. Finally, we suggest future directions both in ichneumonid palaeontology and in the way RoguePlots can improve both assessment and representation of placement uncertainty, both in fossils and other rogue taxa.

Plant interactions shape pollination networks via nonadditive effects.

Plants grow in communities where they interact with other plants and with other living organisms such as pollinators. On the one hand, studies of plant-plant interactions rarely consider how plants interact with other trophic levels such as pollinators. On the other, studies of plant-animal interactions rarely deal with interactions within trophic levels such as plant-plant competition and facilitation. Thus, to what degree plant interactions affect biodiversity and ecological networks across trophic levels is poorly understood. We manipulated plant communities driven by foundation species facilitation and sampled plant-pollinator networks at fine spatial scale in a field experiment in Sierra Nevada, Spain. We found that plant-plant facilitation shaped pollinator diversity and structured pollination networks. Nonadditive effects of plant interactions on pollinator diversity and interaction diversity were synergistic in one foundation species networks while they were additive in another foundation species. Nonadditive effects of plant interactions were due to rewiring of pollination interactions. In addition, plant facilitation had negative effects on the structure of pollination networks likely due to increase in plant competition for pollination. Our results empirically demonstrate how different network types are coupled, revealing pervasive consequences of interaction chains in diverse communities.

Seven remarkable new fossil species of parasitoid wasps (Hymenoptera, Ichneumonidae) from the Eocene Messel Pit.

Parasitoid wasps of the family Ichneumonidae are one of the most diverse and species-rich groups of organisms with a worldwide distribution. We here describe seven new ichneumonid fossil species and two new genera from a remarkable insect fossil site, the Eocene Messel Pit in Germany (~47Ma). The unique fossil preservation allows us to place five out of the seven new species unequivocally in extant subfamilies and genera. For the first time, lobed claws which are a clear synapomorphy for the subfamily Pimplinae, are observed in a fossil, making the newly described Scambus fossilobus sp. nov. the oldest unequivocal representative of the group. We also describe a fossil of Labeninae (Trigonator macrocheirus gen. et sp. nov.), an ichneumonid subfamily that was until now believed to be an exclusively Gondwanan element. Furthermore, the newly described Rhyssella vera sp. nov., Xanthopimpla messelensis sp. nov., and X. praeclara sp. nov. provide evidence that these extant genera date back as far as the Early/Middle Eocene. In contrast to the clear placement of most of the newly described species, we were unable to place Polyhelictes bipolarus gen. et sp. nov. and Mesornatus markovici gen. et sp. nov. in an ichneumonid subfamily, mostly due to the high levels of homoplasy found in this group. These findings on the one hand demonstrate the need for a more rigorous approach in the taxonomic placement of fossil ichneumonids, and on the other hand provide more precise minimum ages for several ichneumonid genera and subfamilies.

More on the Best Evolutionary Rate for Phylogenetic Analysis.

The accumulation of genome-scale molecular data sets for nonmodel taxa brings us ever closer to resolving the tree of life of all living organisms. However, despite the depth of data available, a number of studies that each used thousands of genes have reported conflicting results. The focus of phylogenomic projects must thus shift to more careful experimental design. Even though we still have a limited understanding of what are the best predictors of the phylogenetic informativeness of a gene, there is wide agreement that one key factor is its evolutionary rate; but there is no consensus as to whether the rates derived as optimal in various analytical, empirical, and simulation approaches have any general applicability. We here use simulations to infer optimal rates in a set of realistic phylogenetic scenarios with varying tree sizes, numbers of terminals, and tree shapes. Furthermore, we study the relationship between the optimal rate and rate variation among sites and among lineages. Finally, we examine how well the predictions made by a range of experimental design methods correlate with the observed performance in our simulations.We find that the optimal level of divergence is surprisingly robust to differences in taxon sampling and even to among-site and among-lineage rate variation as often encountered in empirical data sets. This finding encourages the use of methods that rely on a single optimal rate to predict a gene's utility. Focusing on correct recovery either of the most basal node in the phylogeny or of the entire topology, the optimal rate is about 0.45 substitutions from root to tip in average Yule trees and about 0.2 in difficult trees with short basal and long-apical branches, but all rates leading to divergence levels between about 0.1 and 0.5 perform reasonably well.Testing the performance of six methods that can be used to predict a gene's utility against our simulation results, we find that the probability of resolution, signal-noise analysis, and Fisher information are good predictors of phylogenetic informativeness, but they require specification of at least part of a model tree. Likelihood quartet mapping also shows very good performance but only requires sequence alignments and is thus applicable without making assumptions about the phylogeny. Despite them being the most commonly used methods for experimental design, geometric quartet mapping and the integration of phylogenetic informativeness curves perform rather poorly in our comparison. Instead of derived predictors of phylogenetic informativeness, we suggest that the number of sites in a gene that evolve at near-optimal rates (as inferred here) could be used directly to prioritize genes for phylogenetic inference. In combination with measures of model fit, especially with respect to compositional biases and among-site and among-lineage rate variation, such an approach has the potential to greatly improve marker choice and should be tested on empirical data.

Evolutionary History of the Hymenoptera.

Hymenoptera (sawflies, wasps, ants, and bees) are one of four mega-diverse insect orders, comprising more than 153,000 described and possibly up to one million undescribed extant species [1, 2]. As parasitoids, predators, and pollinators, Hymenoptera play a fundamental role in virtually all terrestrial ecosystems and are of substantial economic importance [1, 3]. To understand the diversification and key evolutionary transitions of Hymenoptera, most notably from phytophagy to parasitoidism and predation (and vice versa) and from solitary to eusocial life, we inferred the phylogeny and divergence times of all major lineages of Hymenoptera by analyzing 3,256 protein-coding genes in 173 insect species. Our analyses suggest that extant Hymenoptera started to diversify around 281 million years ago (mya). The primarily ectophytophagous sawflies are found to be monophyletic. The species-rich lineages of parasitoid wasps constitute a monophyletic group as well. The little-known, species-poor Trigonaloidea are identified as the sister group of the stinging wasps (Aculeata). Finally, we located the evolutionary root of bees within the apoid wasp family "Crabronidae." Our results reveal that the extant sawfly diversity is largely the result of a previously unrecognized major radiation of phytophagous Hymenoptera that did not lead to wood-dwelling and parasitoidism. They also confirm that all primarily parasitoid wasps are descendants of a single endophytic parasitoid ancestor that lived around 247 mya. Our findings provide the basis for a natural classification of Hymenoptera and allow for future comparative analyses of Hymenoptera, including their genomes, morphology, venoms, and parasitoid and eusocial life styles.

Post-Eocene climate change across continental Australia and the diversification of Australasian spiny trapdoor spiders (Idiopidae: Arbanitinae).

The formation and spread of the Australian arid zone during the Neogene was a profoundly transformative event in the biogeographic history of Australia, resulting in extinction or range contraction in lineages adapted to mesic habitats, as well as diversification and range expansion in arid-adapted taxa (most of which evolved from mesic ancestors). However, the geographic origins of the arid zone biota are still relatively poorly understood, especially among highly diverse invertebrate lineages, many of which are themselves poorly documented at the species level. Spiny trapdoor spiders (Idiopidae: Arbanitinae) are one such lineage, having mesic 'on-the-continent' Gondwanan origins, while also having experienced major arid zone radiations in select clades. In this study, we present new orthologous nuclear markers for the phylogenetic inference of mygalomorph spiders, and use them to infer the phylogeny of Australasian Idiopidae with a 12-gene parallel tagged amplicon next-generation sequencing approach. We use these data to test the mode and timing of diversification of arid-adapted idiopid lineages across mainland Australia, and employ a continent-wide sampling of the fauna's phylogenetic and geographic diversity to facilitate ancestral area inference. We further explore the evolution of phenotypic and behavioural characters associated with both arid and mesic environments, and test an 'out of south-western Australia' hypothesis for the origin of arid zone clades. Three lineages of Idiopidae are shown to have diversified in the arid zone during the Miocene, one (genus Euoplos) exclusively in Western Australia. Arid zone Blakistonia likely had their origins in South Australia, whereas in the most widespread genus Aganippe, a more complex scenario is evident, with likely range expansion from southern Western Australia to southern South Australia, from where the bulk of the arid zone fauna then originated. In Aganippe, remarkable adaptations to phragmotic burrow-plugging in transitional arid zone taxa have evolved twice independently in Western Australia, while in Misgolas and Cataxia, burrow door-building behaviours have likely been independently lost at least three times in the eastern Australian mesic zone. We also show that the presence of idiopids in New Zealand (Cantuaria) is likely to be the result of recent dispersal from Australia, rather than ancient continental vicariance. By providing the first comprehensive, continental synopsis of arid zone biogeography in an Australian arachnid lineage, we show that the diversification of arbanitine Idiopidae was intimately associated with climate shifts during the Neogene, resulting in multiple Mio-Pliocene radiations.

Revising Australian Pristomerus (Hymenoptera, Ichneumonidae, Cremastinae): species with a tooth on the hind femur.

The Australian insect fauna is among the least-well studied in the world, and conservative estimates state that 75% of the species still await description. In the more species-rich groups, this percentage might be even larger, which is certainly the case in parasitoid wasps which have received very little attention by taxonomists. The genus Pristomerus of the family Ichneumonidae is distributed worldwide, with most species found in the tropics. Its members attack concealed larvae of small Lepidoptera, and several species are used in biocontrol. Five species have been reported from Australia, all of them endemic, but many more undescribed species are present in various collections.        I here revise Australian Pristomerus, focussing on the species that bear a tooth on the ventral side of the hind femur. Twenty-two species are recorded, 19 of which are described as new: Pristomerus australiensis n. sp., P. bertschmanni n. sp., P. callitrinus n. sp., P. dundeei n. sp., P. flavicephalus n. sp., P. fourecksensis n. sp., P. gracilis n. sp., P. kakaduensis n. sp., P. laetus n. sp., P. luculentus n. sp., P. lunatus n. sp., P. mangiferus n. sp., P. merus n. sp., P. nedkellyi n. sp., P. pellicius n. sp., P. periculosus n. sp., P. stellatus n. sp., P. tenebrosus n. sp., and P. venustus n. sp. A dichotomous key and an online interactive key to the known Australian species with a tooth on the hind femur are provided, including photographs of all the species.        The origin of the considerable number of Australian Pristomerus species remains unclear. They might represent Southern relict elements with affinities to South American taxa, or their ancestors might have immigrated from the Paleotropics in more recent times; this question can only be solved with a dated phylogeny of the genus. However, support for a Palaeotropic origin of at least a good portion of the taxa comes from their current distribution, as the Australian Pristomerus are found to be most diverse in the tropical habitats of Northern Queensland and the Northern Territories.

Molecular and morphological phylogenetics of chelonine parasitoid wasps (Hymenoptera: Braconidae), with a critical assessment of divergence time estimations.

Parasitoid wasps of the subfamily Cheloninae are both species rich and poorly known. Although the taxonomy of Cheloninae appears to be relatively stable, there is no clear understanding of relationships among higher-level taxa. We here applied molecular phylogenetic analyses using three markers (COI, EF1α, 28S) and 37 morphological characters to elucidate the evolution and systematics of these wasps. Analyses were based on 83 specimens representing 13 genera. All genera except Ascogaster, Phanerotoma, and Pseudophanerotoma formed monophyletic groups; Furcidentia (stat. rev.) is raised to generic rank. Neither Chelonus (Chelonus) nor Chelonus (Microchelonus) were recovered as monophyletic, but together formed a monophyletic lineage. The tribes Chelonini and Odontosphaeropygini formed monophyletic groups, but the Phanerotomini sensu Zettel and Pseudophanerotomini were retrieved as either para- or polyphyletic. The genera comprising the former subfamily Adeliinae were confirmed as being nested within the Cheloninae. To estimate the age of the subfamily, we used 16 fossil taxa. Three approaches were compared: fixed-rate dating, node dating, and total-evidence dating, with age estimates differing greatly between the three methods. Shortcomings of each approach in relation to our dataset are discussed, and none of the age estimates is deemed sufficiently reliable. Given that most dating studies use a single method only, in most cases without presenting analyses on the sensitivity to priors, it is likely that numerous age estimates in the literature suffer from a similar lack of robustness. We argue for a more rigorous approach to dating analyses and for a faithful presentation of uncertainties in divergence time estimates. Given the results of the phylogenetic analysis the following taxonomic changes are proposed: Furcidentia Zettel (stat. rev.), previously treated as a subgenus of Pseudophanerotoma Zettel is raised to generic rank; Microchelonus Szépligeti (syn. nov.), variously treated by previous authors, is proposed as a junior synonym of Chelonus Jurine; the following subgenera of Microchelonus - Baculonus Braet & van Achterberg (syn. nov.), Carinichelonus Tobias (syn. nov.) and Scabrichelonus He, Chen & van Achterberg (syn. nov.), are proposed as junior synonyms of Chelonus; a number of new species names are proposed due to homonyms resulting from the above changes and these are listed in the paper.

Total-Evidence Dating under the Fossilized Birth-Death Process.

Bayesian total-evidence dating involves the simultaneous analysis of morphological data from the fossil record and morphological and sequence data from recent organisms, and it accommodates the uncertainty in the placement of fossils while dating the phylogenetic tree. Due to the flexibility of the Bayesian approach, total-evidence dating can also incorporate additional sources of information. Here, we take advantage of this and expand the analysis to include information about fossilization and sampling processes. Our work is based on the recently described fossilized birth-death (FBD) process, which has been used to model speciation, extinction, and fossilization rates that can vary over time in a piecewise manner. So far, sampling of extant and fossil taxa has been assumed to be either complete or uniformly at random, an assumption which is only valid for a minority of data sets. We therefore extend the FBD process to accommodate diversified sampling of extant taxa, which is standard practice in studies of higher-level taxa. We verify the implementation using simulations and apply it to the early radiation of Hymenoptera (wasps, ants, and bees). Previous total-evidence dating analyses of this data set were based on a simple uniform tree prior and dated the initial radiation of extant Hymenoptera to the late Carboniferous (309 Ma). The analyses using the FBD prior under diversified sampling, however, date the radiation to the Triassic and Permian (252 Ma), slightly older than the age of the oldest hymenopteran fossils. By exploring a variety of FBD model assumptions, we show that it is mainly the accommodation of diversified sampling that causes the push toward more recent divergence times. Accounting for diversified sampling thus has the potential to close the long-discussed gap between rocks and clocks. We conclude that the explicit modeling of fossilization and sampling processes can improve divergence time estimates, but only if all important model aspects, including sampling biases, are adequately addressed.

A Nonstationary Markov Model Detects Directional Evolution in Hymenopteran Morphology.

Directional evolution has played an important role in shaping the morphological, ecological, and molecular diversity of life. However, standard substitution models assume stationarity of the evolutionary process over the time scale examined, thus impeding the study of directionality. Here we explore a simple, nonstationary model of evolution for discrete data, which assumes that the state frequencies at the root differ from the equilibrium frequencies of the homogeneous evolutionary process along the rest of the tree (i.e., the process is nonstationary, nonreversible, but homogeneous). Within this framework, we develop a Bayesian approach for testing directional versus stationary evolution using a reversible-jump algorithm. Simulations show that when only data from extant taxa are available, the success in inferring directionality is strongly dependent on the evolutionary rate, the shape of the tree, the relative branch lengths, and the number of taxa. Given suitable evolutionary rates (0.1-0.5 expected substitutions between root and tips), accounting for directionality improves tree inference and often allows correct rooting of the tree without the use of an outgroup. As an empirical test, we apply our method to study directional evolution in hymenopteran morphology. We focus on three character systems: wing veins, muscles, and sclerites. We find strong support for a trend toward loss of wing veins and muscles, while stationarity cannot be ruled out for sclerites. Adding fossil and time information in a total-evidence dating approach, we show that accounting for directionality results in more precise estimates not only of the ancestral state at the root of the tree, but also of the divergence times. Our model relaxes the assumption of stationarity and reversibility by adding a minimum of additional parameters, and is thus well suited to studying the nature of the evolutionary process in data sets of limited size, such as morphology and ecology.

Does early learning drive ecological divergence during speciation processes in parasitoid wasps?

Central to the concept of ecological speciation is the evolution of ecotypes, i.e. groups of individuals occupying different ecological niches. However, the mechanisms behind the first step of separation, the switch of individuals into new niches, are unclear. One long-standing hypothesis, which was proposed for insects but never tested, is that early learning causes new ecological preferences, leading to a switch into a new niche within one generation. Here, we show that a host switch occurred within a parasitoid wasp, which is associated with the ability for early learning and the splitting into separate lineages during speciation. Lariophagus distinguendus consists of two genetically distinct lineages, most likely representing different species. One attacks drugstore beetle larvae (Stegobium paniceum (L.)), which were probably the ancestral host of both lineages. The drugstore beetle lineage has an innate host preference that cannot be altered by experience. In contrast, the second lineage is found on Sitophilus weevils as hosts and changes its preference by early learning. We conclude that a host switch has occurred in the ancestor of the second lineage, which must have been enabled by early learning. Because early learning is widespread in insects, it might have facilitated ecological divergence and associated speciation in this hyperdiverse group.

Revision of the Western Palaearctic Diplazontinae (Hymenoptera, Ichneumonidae).

I revise the subfamily Diplazontinae to include 99 Western Palaearctic species, review morphological characters useful for species delimitation and identification, and clarify the status of some morphologically similar taxa using molecular approaches. Illustrated, dichotomous keys to the Western Palaearctic genera and species of the subfamily are presented, and the utility of the molecular markers CO1 and ITS2 for species delimitation in Diplazontinae is discussed. Seven new species are described, Diplazon flixi sp. nov., Diplazon nordicus sp. nov., Diplazon parvus sp. nov., Diplazon zetteli sp. nov., Eurytyloides umbrinus sp. nov., Sussaba roberti sp. nov., and Woldstedtius bauri sp. nov. The Nearctic Sussaba cultriformis (Ashmead), formerly a subspecies of Sussaba dorsalis (Holmgren), is raised to species rank. The following taxa are valid species and hereby removed from synonymy: Episemura ensata (Bauer), stat. rev.; Homotropus frontorius (Thunberg), stat. rev.; Syrphoctonus desvignesii (Marshall), stat. rev.; Syrphophilus scabriculus (Holmgren), stat. rev.; and Tymmophorus suspiciosus (Brischke), stat. rev. Nineteen new synonyms are established: Bioblapsis mallochi Rotheray of Bioblapsis cultiformis (Davis), syn. nov.; Bioblapsis tricincta Ashmead of Syrphophilus scabriculus (Holmgren), syn. nov.; Diplazon bachmaieri Diller of Diplazon angustus Dasch, syn. nov.; Diplazon fechteri Diller of Diplazon cascadensis Dasch, syn. nov.; Homocidus brevis Hedwig of Homotropus pictus (Gravenhorst); Homocidus rubiginosum Schmiedeknecht of Enizemum scutellare (Lange), syn. nov.; Homocidus simulans Stelfox of Homotropus collinus (Stelfox), syn. nov.; Homotropus crassicrus Thomson and Homotropus nudus Dasch of Homotropus dimidiatus (Schrank), syn. nov.; Homocidus asyntactus Schmiedeknecht of Homotropus crassicornis Thomson, syn. nov.; Homocidus subopacus Stelfox and Homotropus quadrangularis Dasch of Homotropus frontorius (Thunberg), syn. nov.; Homocidus impolitus Stelfox of Homotropus pallipes (Gravenhorst), syn. nov.; Homotropus incisus Thomson and Homotropus reflexus Morley of Homotropus pectoralis (Provancher), syn. nov.; Tryphon nigricornis Zetterstedt, a former synonym of H. dimidiatus Schrank, is a synonym of Homotropus pictus (Gravenhorst), syn. nov.; Homotropus fraudulentus Dasch and Homotropus neopulcher Horstmann of Syrphoctonus desvignesii (Marshall), syn. nov.; Homotropus eximius Habermehl of Syrphoctonus tarsatorius (Panzer), syn. nov. The following new combinations are established: Bioblapsis cultiformis (Davis), comb. nov.; Homotropus collinus (Stelfox), comb. nov.; Homotropus dimidiatus (Schrank), comb. nov.; Homotropus frontorius (Thunberg), comb. nov.; Homotropus pectoralis (Provancher), comb. nov.; Homotropus strigator (Fabricius), comb. nov.; Homotropus sundevalli (Holmgren), comb. nov. The present revision is the first comprehensive treatment of the Western Palaearctic Diplazontinae, provides the basis for taxonomic, faunistic, ecological and evolutionary studies in these hoverfly parasitoids, and exemplifies an integrative approach to systematics and taxonomy.

Review of the Diplazontinae (Hymenoptera, Ichneumonidae) of the Kuril islands, with descriptions of two new species.

A sample of 346 specimens of Diplazontinae parasitoid wasps from the Kuril islands was studied. Twenty-six species are reported, Tymmophorus gelidus Dasch for the first time for the Eastern Palaearctic. Two new species are described, Diplazon kurilensis sp. n. and Homotropus formosus sp. n. Diplazon urupensis Uchida is removed from synonymy (stat. rev.), and Promethes persulcatus Nakanishi is suggested as a synonym of Promethes bridgmani Fitton. Reasons are discussed for the large proportion of species with a Holarctic or even multi-regional distribution in the sample, which amounts to17 of the species or 65%.