New Caledonia has generally been considered a continental island, the biota of which largely dates back to Gondwanan times owing to its geological origin and the presence of phylogenetic relicts. This view is contradicted by geological evidence indicating long Palaeocene and Eocene submersions and by recent biogeographic and phylogenetic studies, with molecular or geophysical dating placing the biota no older than the Oligocene. Phylogenetic relicts do not provide conclusive information in this respect, as their presence cannot be explained by simple hypotheses but requires assumption of many ad hoc extinction events. The implication of this new scenario is that all the New Caledonian biota colonized the island since 37 Ma Local richness can be explained by local radiation and adaptation after colonization but also by many dispersal events, often repeated within the same groups of organisms. Local microendemism is another remarkable feature of the biota. It seems to be related to recent speciation mediated by climate, orography, soil type and perhaps unbalanced biotic interactions created by colonization disharmonies. New Caledonia must be considered as a very old Darwinian island, a concept that offers many more fascinating opportunities of study.
Orthoptera is the most diverse order among the polyneopteran groups and includes familiar insects, such as grasshoppers, crickets, katydids, and their kin. Due to a long history of conflicting classification schemes based on different interpretations of morphological characters, the phylogenetic relationships within Orthoptera are poorly understood and its higher classification has remained unstable. In this study, we establish a robust phylogeny of Orthoptera including 36 of 40 families representing all 15 currently recognized superfamilies and based on complete mitochondrial genomes and four nuclear loci, in order to test previous phylogenetic hypotheses and to provide a framework for a natural classification and a reference for studying the pattern of divergence and diversification. We find strong support for monophyletic suborders (Ensifera and Caelifera) as well as major superfamilies. Our results corroborate most of the higher‐level relationships previously proposed for Caelifera, but suggest some novel relationships for Ensifera. Using fossil calibrations, we provide divergence time estimates for major orthopteran lineages and show that the current diversity has been shaped by dynamic shifts of diversification rates at different geological times across different lineages. We also show that mitochondrial tRNA gene orders have been relatively stable throughout the evolutionary history of Orthoptera, but a major tRNA gene rearrangement occurred in the common ancestor of Tetrigoidea and Acridomorpha, thereby representing a robust molecular synapomorphy, which has persisted for 250 Myr.
Ensifera present an appropriate and interesting model for the study of acoustic communication, because of their diverse signal and communication modalities, and due to their accessibility for field and laboratory studies. Several hypotheses have been proposed to explain the acoustic evolution of Ensifera, but they were elaborated without any reference to a falsifiable phylogeny, and were consequently highly speculative. Similarly, phylogenetic relationships between ensiferan clades have not hitherto been studied using modern standard methodology, and the sole cladistic analysis by Gwynne in 1995 was methodologically flawed. No sound hypothesis therefore currently exists for ensiferan phylogeny, which precludes historical analysis of their communication modalities. In the present paper, the phylogeny is established on the basis of morpho‐anatomical characters and used to analyse the evolution of acoustic communication in this clade by mapping the characters related to auditory and stridulatory structures onto the resultant trees. Cladistic analyses resulted in two equi‐parsimonious cladograms (length 154, C 64, CI 58, RI 61) with the following topologies: (1) [(Grylloidea–Gryllotalpidae) (Rhaphidophoridae (Schizodactylidae (Gryllacrididae ((Stenopelmatidae–Cooloola) (Anostostomatidae (Prophalangopsis (Cyphoderris (Tettigoniidae–Lezina))))))))] (2) [(Grylloidea–Gryllotalpidae)(Rhaphidophoridae (Schizodactylidae (Gryllacrididae–Cooloola–(Stenopelmatidae (Anostostomatidae (Prophalangopsis (Cyphoderris (Tettigoniidae–Lezina))))))))]. According to these topologies, Ensifera were ancestrally devoid of acoustic and hearing systems. An acoustic (tegminal or femoro‐abdominal) apparatus appeared a number of times independently with convergent structures. Similarly, tibial tympana developed several times independently. Moreover, four hypotheses (each according to a definite pattern of character transformation) can be proposed to explain the evolution of acoustic communication in the different ensiferan clades and relate it to a definite communicatory context. These hypotheses do not apply equally to ensiferan subclades. Grylloidea and Gryllotalpoidea could have experienced convergently a direct development of an intraspecific acoustic communication. Acoustic communication in Tettigoniidea has evolved more ambiguously, and may either have resulted from a direct evolution analogous to that having occurred in Gryllidea, or have developed in a completely different behavioural context. Future studies of acoustic communication in the different ensiferan clades will have to take into account the fact that the involved structures most often are not homologous and that their evolution may not have taken place in similar conditions. Different hypotheses of acoustic communication evolution may apply to different clades, and there may be no single explanation for acoustic communication in Ensifera.
The Eumetabola (Endopterygota (also known as Holometabola) plus Paraneoptera) have the highest number of species of any clade, and greatly contribute to animal species biodiversity. The palaeoecological circumstances that favoured their emergence and success remain an intriguing question. Recent molecular phylogenetic analyses have suggested a wide range of dates for the initial appearance of the Holometabola, from the Middle Devonian epoch (391 million years (Myr) ago) to the Late Pennsylvanian epoch (311 Myr ago), and Hemiptera (310 Myr ago). Palaeoenvironments greatly changed over these periods, with global cooling and increasing complexity of green forests. The Pennsylvanian-period crown-eumetabolan fossil record remains notably incomplete, particularly as several fossils have been erroneously considered to be stem Holometabola (Supplementary Information); the earliest definitive beetles are from the start of the Permian period. The emergence of the hymenopterids, sister group to other Holometabola, is dated between 350 and 309 Myr ago, incongruent with their current earliest record (Middle Triassic epoch). Here we describe five fossils--a Gzhelian-age stem coleopterid, a holometabolous larva of uncertain ordinal affinity, a stem hymenopterid, and early Hemiptera and Psocodea, all from the Moscovian age--and reveal a notable penecontemporaneous breadth of early eumetabolan insects. These discoveries are more congruent with current hypotheses of clade divergence. Eumetabola experienced episodes of diversification during the Bashkirian-Moscovian and the Kasimovian-Gzhelian ages. This cladogenetic activity is perhaps related to notable episodes of drying resulting from glaciations, leading to the eventual demise in Euramerica of coal-swamp ecosystems, evidenced by floral turnover during this interval. These ancient species were of very small size, living in the shadow of Palaeozoic-era 'giant' insects. Although these discoveries reveal unexpected Pennsylvanian eumetabolan diversity, the lineage radiated more successfully only after the mass extinctions at the end of the Permian period, giving rise to the familiar crown groups of their respective clades.
Calling with a tegminal stridulatory apparatus is widespread in crickets. However, the evolution of cricket stridulums has been poorly studied and then only on the basis of prephylogenetic models, which are unable to account for the huge diversity recently documented for acoustic features in crickets. The present paper focuses on the evolution of acoustic devices in the subfamily Eneopterinae. This is the first attempt to reconstruct the phylogeny of a large and diverse cricket clade in order to analyze the evolution of emitting structures using precise homology statements. In the first step, we reconstruct the phylogeny of this clade using a morphological data set of 193 characters and 45 taxa. The resultant phylogeny supports the monophyly of the subfamily and that of the 13 genera represented by at least two species in our taxonomic sample. Phylogenetic relationships within the subfamily also support the definition of five tribes: Eurepini, Eneopterini, Nisitrini, Xenogryllini and Lebinthini. In the second step, the evolution of acoustic devices is studied by optimization of venation characters defined on precise homology statements. As hypothesized by previous authors, losses of acoustic communication occur independently in the course of eneopterine evolution; however, they happen abruptly with no intermediate state. Our results also document for the first time the modalities of forewing evolution: the diversification of male forewing venation originates from two processes, a continuous and regular modification process, responsible for slight venation change; and an irregular, more intense punctuated process, allowing the emergence of different venations. This diversification process with sudden changes could be related to the occurrence of acoustic novelties in advertisement calls.
Orthoptera have been used for decades for numerous evolutionary questions but several of its constituent groups, notably crickets, still suffer from a lack of a robust phylogenetic hypothesis. We propose the first phylogenetic hypothesis for the evolution of crickets sensu lato, based on analysis of 205 species, representing 88% of the subfamilies and 71% tribes currently listed in the database Orthoptera Species File (OSF). We reconstructed parsimony, maximum likelihood and Bayesian phylogenies using fragments of 18S, 28SA, 28SD, H3, 12S, 16S, and cytb (~3600 bp). Our results support the monophyly of the cricket clade, and its subdivision into two clades: mole crickets and ant‐loving crickets on the one hand, and all the other crickets on the other (i.e. crickets sensu stricto). Crickets sensu stricto form seven monophyletic clades, which support part of the OSF families, “subfamily groups”, or subfamilies: the mole crickets (OSF Gryllotalpidae), the scaly crickets (OSF Mogoplistidae), and the true crickets (OSF Gryllidae) are recovered as monophyletic. Among the 22 sampled subfamilies, only six are monophyletic: Gryllotalpinae, Trigonidiinae, Pteroplistinae, Euscyrtinae, Oecanthinae, and Phaloriinae. Most of the 37 tribes sampled are para‐ or polyphyletic. We propose the best‐supported clades as backbones for future definitions of familial groups, validating some taxonomic hypotheses proposed in the past. These clades fit variously with the morphological characters used today to identify crickets. Our study emphasizes the utility of a classificatory system that accommodates diagnostic characters and monophyletic units of evolution. Moreover, the phylogenetic hypotheses proposed by the present study open new perspectives for further evolutionary research, especially on acoustic communication and biogeography.
Aim A New Caledonian insect group was studied in a world‐wide phylogenetic context to test: (1) whether local or regional island clades are older than 37 Ma, the postulated re‐emergence time of New Caledonia; (2) whether these clades show evidence for local radiations or multiple colonizations; and (3) whether there is evidence for relict taxa with long branches in phylogenetic trees that relate New Caledonian species to geographically distant taxa. Location New Caledonia, south‐west Pacific. Methods We sampled 43 cricket species representing all tribes of the subfamily Eneopterinae and 15 of the 17 described genera, focusing on taxa distributed in the South Pacific and around New Caledonia. One nuclear and three mitochondrial genes were analysed using Bayesian and parsimony methods. Phylogenetic divergence times were estimated using a relaxed clock method and several calibration criteria. Results The analyses indicate that, under the most conservative dating scenario, New Caledonian eneopterines are 5–16 million years old. The largest group in the Pacific region dates to 18–29 Ma. New Caledonia has been colonized in two phases: the first around 10.6 Ma, with the subsequent diversification of the endemic genus Agnotecous, and the second with more recent events around 1–4 Ma. The distribution of the sister group of Agnotecous and the lack of phylogenetic long branches in the genus refute an assumption of major extinction events in this clade and the hypothesis of local relicts. Main conclusions Our phylogenetic studies invalidate a simple scenario of local persistence of this group in New Caledonia since 80 Ma, either by survival on the New Caledonian island since its rift from Australia, or, if one accepts the submergence of New Caledonia, by local island‐hopping among other subaerial islands, now drowned, in the region during periods of New Caledonian submergence.
In zoological nomenclature, to be potentially valid, nomenclatural novelties (i.e., new nomina and nomenclatural acts) need first to be made available, that is, published in works qualifying as publications as defined by the International Code of zoological Nomenclature ("the Code"). In September 2012, the Code was amended in order to allow the recognition of works electronically published online after 2011 as publications available for the purpose of zoological nomenclature, provided they meet several conditions, notably a preregistration of the work in ZooBank. Despite these new Rules, several of the long-discussed problems concerning the electronic publication of new nomina and nomenclatural acts have not been resolved. The publication of this amendment provides an opportunity to discuss some of these in detail. It is important to note that: (1) all works published only online before 2012 are nomenclaturally unavailable; (2) printed copies of the PDFs of works which do not have their own ISSN or ISBN, and which are not obtainable free of charge or by purchase, do not qualify as publications but must be seen as facsimiles of unavailable works and are unable to provide nomenclatural availability to any nomenclatural novelties they may contain; (3) prepublications online of later released online publications are unavailable, i.e., they do not advance the date of publication; (4) the publication dates of works for which online prepublications had been released are not those of these prepublications and it is critical that the real release date of such works appear on the actual final electronic publication, but this is not currently the case in electronic periodicals that distribute such online prepublications and which still indicate on their websites and PDFs the date of release of prepublication as that of publication of the work; (5) supplementary online materials and subsequent formal corrections of either paper or electronic publications distributed only online are nomenclaturally unavailable; (6) nomenclatural information provided on online websites that do not have a fixed content and format, with ISSN or ISBN, is unavailable. We give precise examples of many of these nomenclatural problems. Several of them, when they arise, are due to the fact that the availability of nomenclatural novelties now depends on information that will have to be sought not from the work itself but from extrinsic evidence. As shown by several examples discussed here, an electronic document can be modified while keeping the same DOI and publication date, which is not compatible with the requirements of zoological nomenclature. Therefore, another system of registration of electronic documents as permanent and inalterable will have to be devised. ZooBank also clearly needs to be improved in several respects. Mention in a work of its registration number (LSID) in ZooBank would seem to be possible only if this registration has occurred previously, but some works that have purportedly been registered in ZooBank are in fact missing on t...
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