The beetle tree of life reveals that Coleoptera survived end‐Permian mass extinction to diversify during the Cretaceous terrestrial revolution

Here we present a phylogeny of beetles (Insecta: Coleoptera) based on DNA sequence data from eight nuclear genes, including six single‐copy nuclear protein‐coding genes, for 367 species representing 172 of 183 extant families. Our results refine existing knowledge of relationships among major groups of beetles. Strepsiptera was confirmed as sister to Coleoptera and each of the suborders of Coleoptera was recovered as monophyletic. Interrelationships among the suborders, namely Polyphaga (Adephaga (Archostemata, Myxophaga)), in our study differ from previous studies. Adephaga comprised two clades corresponding to Hydradephaga and Geadephaga. The series and superfamilies of Polyphaga were mostly monophyletic. The traditional Cucujoidea were recovered in three distantly related clades. Lymexyloidea was recovered within Tenebrionoidea. Several of the series and superfamilies of Polyphaga received moderate to maximal clade support in most analyses, for example Buprestoidea, Chrysomeloidea, Coccinelloidea, Cucujiformia, Curculionoidea, Dascilloidea, Elateroidea, Histeroidea and Hydrophiloidea. However, many of the relationships within Polyphaga lacked compatible resolution under maximum‐likelihood and Bayesian inference, and/or lacked consistently strong nodal support. Overall, we recovered slightly younger estimated divergence times than previous studies for most groups of beetles. The ordinal split between Coleoptera and Strepsiptera was estimated to have occurred in the Early Permian. Crown Coleoptera appeared in the Late Permian, and only one or two lineages survived the end‐Permian mass extinction, with stem group representatives of all four suborders appearing by the end of the Triassic. The basal split in Polyphaga was estimated to have occurred in the Triassic, with the stem groups of most series and superfamilies originating during the Triassic or Jurassic. Most extant families of beetles were estimated to have Cretaceous origins. Overall, Coleoptera experienced an increase in diversification rate compared to the rest of Neuropteroidea. Furthermore, 10 family‐level clades, all in suborder Polyphaga, were identified as having experienced significant increases in diversification rate. These include most beetle species with phytophagous habits, but also several groups not typically or primarily associated with plants. Most of these groups originated in the Cretaceous, which is also when a majority of the most species‐rich beetle families first appeared. An additional 12 clades showed evidence for significant decreases in diversification rate. These clades are species‐poor in the Modern fauna, but collectively exhibit diverse trophic habits. The apparent success of beetles, as measured by species numbers, may result from their associations with widespread and diverse substrates – especially plants, but also including fungi, wood and leaf litter – but what facilitated these associations in the first place or has allowed these associations to flourish likely varies within and between lineages. Our results provide a uniquely well‐resolved temporal and phylogenetic framework for studying patterns of innovation and diversification in Coleoptera, and a foundation for further sampling and resolution of the beetle tree of life.     

Molecules,morphology and minute hooded beetles: a phylogenetic study with implications for the evolution and classification of Corylophidae (Coleoptera: Cucujoidea)

Eight genes (nuclear: 18S, 28S, H3, CAD; mitochondrial: 12S, 16S, COI, COII) and morphology were used to infer the evolutionary history of Corylophidae, some of the smallest free‐living insects. The study included 36 corylophid exemplars, representing approximately 60% of the known generic diversity of the family and 16 cucujoid outgroup taxa. Multiple partitioning strategies, molecular datasets, combined datasets and different taxon sampling regimes using maximum likelihood and mixed‐model Bayesian inference were utilized to analyse these data. Most results were highly concordant across analyses. There was strong agreement across (i) partitioning strategies, (ii) maximum likelihood and Bayesian inference analyses of the molecular data, and (iii) Bayesian inference of the molecular data alone and Bayesian inference of the combined morphological and molecular data when all terminal taxa were included. When a strict taxon sampling protocol was employed so that only single generic exemplars were included, deep relationships were affected in the resulting phylogenetic hypotheses. Under such narrow sampling strategies, deep phylogenetic relationships were also sensitive to the choice of generic exemplars. Although it is often challenging to obtain single representatives for many taxa in higher‐level phylogenetic analyses, these results indicate the importance of using denser taxon sampling approaches even at the specific level for genera included in such studies. Molecular data alone support Anamorphinae (Endomychidae) strongly as the sister group of Corylophidae. In combined data analyses, Coccinellidae is recovered as the sister group to Corylophidae. In all analyses, Corylophidae and the subfamily Corylophinae are recovered as monophyletic. The monophyly of Periptyctinae was untested, as only a single species was included. All included corylophine tribes were recovered as monophyletic with the exception of Aenigmaticini; Aenigmaticum Matthews forms the sister group to Orthoperus Stephens and Stanus?lipiński et al. is recovered as the sister group of Sericoderus Stephens. Stanus tasmanicus?lipiński et al. is transferred to a new genus, Pseudostanus Robertson, ?lipiński & McHugh gen.n. incertae sedis. We propose a new tribe, Stanini Robertson, ?lipiński & McHugh trib.n. for Stanus bowesteadi?lipiński et al. and a new concept of Aenigmaticini sensu.n. to include only the nominate genus. Anatomical transitions associated with corylophid miniaturization are highlighted. Key phenotypic modifications and elevated rates of substitution in nuclear rRNA genes are evident in a subgroup of Corylophinae that includes the most diminutive species. Other taxonomic and evolutionary implications are discussed in light of the results.     

Body size‐dependent responses of a marine fish assemblage to climate change and fishing over a century‐long scale

Commercial fishing and climate change have influenced the composition of marine fish assemblages worldwide, but we require a better understanding of their relative influence on long‐term changes in species abundance and body‐size distributions. In this study, we investigated long‐term (1911–2007) variability within a demersal fish assemblage in the western English Channel. The region has been subject to commercial fisheries throughout most of the past century, and has undergone interannual changes in sea temperature of over 2.0 °C. We focussed on a core 30 species that comprised 99% of total individuals sampled in the assemblage. Analyses showed that temporal trends in the abundance of smaller multispecies size classes followed thermal regime changes, but that there were persistent declines in abundance of larger size classes. Consistent with these results, larger‐growing individual species had the greatest declines in body size, and the most constant declines in abundance, while abundance changes of smaller‐growing species were more closely linked to preceding sea temperatures. Together these analyses are suggestive of dichotomous size‐dependent responses of species to long‐term climate change and commercial fishing over a century scale. Small species had rapid responses to the prevailing thermal environment, suggesting their life history traits predisposed populations to respond quickly to changing climates. Larger species declined in abundance and size, reflecting expectations from sustained size‐selective overharvesting. These results demonstrate the importance of considering species traits when developing indicators of human and climatic impacts on marine fauna.     

Testing the host‐finding ability of a monophagous caterpillar in the field

1. Relatively few studies of the host‐finding ability of specialised, phytophagous insects involve direct observations of individual insects moving among intact hosts and non‐hosts. Information from such studies can inform the design of restoration programmes for species of conservation concern. 2. The movement of caterpillars of the threatened Oregon silverspot butterfly, Speyeria zerene hippolyta (Edwards) (Lepidoptera: Nymphalidae) was studied in the field in cleared arenas with 10 cm radii. Caterpillars were placed in the centre, surrounded by three individuals of their host, Viola adunca, and three different non‐host individuals, separated by bare ground. In a second experiment, second instars were placed between a host and a non‐host, 3–6 cm away. Caterpillars were observed to determine if they walked to their host more often than expected by chance. 3. Caterpillars walked to vegetation significantly more often than expected by chance. They did not, however, reach their hosts more often than expected, based on plant availability. 4. It is concluded that S. z. hippolyta caterpillars can distinguish vegetation from bare ground from 10 cm away. There is no evidence that they can distinguish their host plant from other herbaceous species at distances of 3 cm.     

A molecular phylogenetic study of Cucujidae s.l. (Coleoptera: Cucujoidea)

Of all the superfamilies within the megadiverse order Coleoptera (Insecta), Cucujoidea (Cucujiformia) is arguably the most problematic taxonomically. The families comprising Cucujidae s.l. (Silvanidae, Laemophloeidae, Passandridae and Cucujidae s.s. represent a large portion of cucujoid diversity. Herein we present the results of a rigorous molecular phylogenetic analysis of Cucujidae s.l. using maximum‐likelihood and Bayesian analyses of seven genes. Representatives of over half of the families of Cucujoidea (excluding the cerylonid series), as well as a broad sampling of Silvanidae and Laemophloeidae, were analysed. The monophyly of Cucujidae s.l. is rejected but a subgrouping of taxa that may form the core of a natural cucujoid lineage is recovered. This clade consists of two large monophyletic groups including several families each. Relationships among these smaller cucujoid groups are discussed, including several novel phylogenetic hypotheses, whereas morphological characters considered significant for classification in Cucujidae s.l. are evaluated in light of these phylogenetic hypotheses. Silvaninae, Telephanini, Brontini and Brontinae are recovered as monophyletic in the Bayesian analysis, but the former two are recovered as paraphyletic in the maximum‐likelihood analysis. Our results support the placement of Psammoecus Latreille within Telephanini and also recover a paraphyletic Telephanus Erichson. Silvaninae is divided into three lineages, each representing a potential tribal lineage. Laemophloeidae is rendered paraphyletic in all analyses by Propalticidae and the latter is herein formally transferred to Laemophloeidae stat.n . Several suprageneric laemophloeid clades are recovered and discussed as potential higher‐level groups. Laemophloeus Dejean is not recovered as monophyletic.     

Deciphering Metazoan Phylogeny: The Need for Additional Molecular Data

SYNOPSIS. Our interpretation of the evolution of development,morphology, and diversity of multicellular animals hinges ona clear understanding of the phylogenetic relationships of metazoans.Currently, the field of metazoan phylogeny is in a state offlux, with new hypotheses of metazoan relationships emergingfrom analyses of 18S rDNA sequence data. Some of these analyseshave been limited in the numbers of taxa analyzed, others, withnumerous taxa analyzed, have not resolved deep level branchingpatterns, and all are hampered by properties of the 18S geneitself. Corroboration of the results from 18S rDNA analysescan come from additional molecular data sets, such as highlyconserved nuclear coding genes, mitochondria gene order, orgene duplication events. The enormous task of data accumulationfor additional molecular data from many representative taxacan most efficiently be undertaken in a coordinated, collaborativeeffort among different lab groups. Ultimately, a combined analysisof several independent data sets will be possible and may providea more stable, robust phylogeny for the Metazoa.     

Phylogeny and classification of Cucujoidea and the recognition of a new superfamily Coccinelloidea (Coleoptera: Cucujiformia)

A large‐scale phylogenetic study is presented for Cucujoidea (Coleoptera), a diverse superfamily of beetles that historically has been taxonomically difficult. This study is the most comprehensive analysis of cucujoid taxa to date, with DNA sequence data sampled from eight genes (four nuclear, four mitochondrial) for 384 coleopteran taxa, including exemplars of 35 (of 37) families and 289 genera of Cucujoidea. Maximum‐likelihood analyses of these data present many significant relationships, some proposed previously and some novel. Tenebrionoidea and Lymexyloidea are recovered together and Cleroidea forms the sister group to this clade. Chrysomeloidea and Curculionoidea are recovered as sister taxa and this clade (Phytophaga) forms the sister group to the core Cucujoidea (Cucujoidea s.n .). The nitidulid series is recovered as the earliest‐diverging core cucujoid lineage, although the earliest divergences among core Cucujoidea are only weakly supported. The cerylonid series (CS) is recovered as monophyletic and is supported as a major Cucujiform clade, sister group to the remaining superfamilies of Cucujiformia. Currently recognized taxa that were not recovered as monophyletic include Cucujoidea, Endomychidae, Cerylonidae and Bothrideridae. Biphyllidae and Byturidae were recovered in Cleroidea. The remaining Cucujoidea were recovered in two disparate major clades: one comprising the nitidulid series + erotylid series + Boganiidae and Hobartiidae + cucujid series, and the other comprising the cerylonid series. Propalticidae are recovered within Laemophloeidae. The cerylonid series includes two major clades, the bothriderid group and the coccinellid group. Akalyptoischiidae are recovered as a separate clade from Latridiidae. Eupsilobiinae are recovered as the sister taxon to Coccinellidae. In light of these findings, many formal changes to cucujiform beetle classification are proposed. Biphyllidae and Byturidae are transferred to Cleroidea. The cerylonid series is formally recognized as a new superfamily, Coccinelloidea stat.n. Current subfamilies elevated (or re‐elevated) to family status include: Murmidiidae stat.n. , Teredidae stat.n. , Euxestidae stat.n. , Anamorphidae stat.rev. , Eupsilobiidae stat.n. , and Mycetaeidae stat.n. The following taxa are redefined and characterized: Cleroidea s.n. , Cucujoidea s.n. , Cerylonidae s.n. , Bothrideridae s.n. , Endomychidae s.n. A new subfamily, Cyclotominae stat.n. , is described. Stenotarsinae syn.n. is formally subsumed within a new concept of Endomychinae s.n.