David C. Hawks

Bio: David C. Hawks is an academic researcher from University of California, Riverside. The author has contributed to research in topics: Catocala & Monophyly. The author has an hindex of 10, co-authored 16 publications receiving 1121 citations.

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

Abstract: © 2015 The Authors. Systematic Entomology published by John Wiley & Sons Ltd on behalf of Royal Entomological Society This is an open access article under the terms of the Creative Commons AttributionߚNonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Phylogeny and evolution of Staphyliniformia and Scarabaeiformia: forest litter as a stepping stone for diversification of nonphytophagous beetles

Abstract: The beetle series Staphyliniformia exhibits extraordinary taxonomic, ecological and morphological diversity. To gain further insight into staphyliniform relationships and evolution, we reconstructed the phylogeny of Staphyliniformia using DNA sequences from nuclear 28S rDNA and the nuclear protein-coding gene CAD for 282 species representing all living families and most subfamilies, a representative sample of Scarabaeiformia serving as a near outgroup, and three additional beetles as more distant outgroups. Under both Bayesian inference (BI) and maximum likelihood inference (MLI), the major taxa within Staphyliniformia are each monophyletic: (i) Staphylinoidea, (ii) Hydrophiloidea s.l., and the contained superfamilies (iii) Hydrophiloidea s.s. and (iv) Histeroidea, although Staphylinoidea and Hydrophiloidea s.l. are not strongly supported by MLI bootstrap. Scarabaeiformia is monophyletic under both methods of phylogenetic inference. However, the relative relationships of Staphylinoidea, Hydrophiloidea s.l. and Scarabaeiformia differ between BI and MLI: under BI, Staphyliniformia and Scarabaeiformia were sister groups; under MLI, Hydrophiloidea s.l. and Scarabaeiformia were sister groups and these together were sister to Staphylinoidea. The internal relationships in Scarabaeiformia were similar under both methods of phylogenetic inference, with Cetoniinae, Dynastinae + Rutelinae, Hybosoridae, Passalidae, Scarabaeidae and Scarabaeinae recovered as monophyla. Histeridae comprised two major clades: (1) Abraeinae, Trypanaeine and Trypeticinae; and (2) Chlamydopsinae, Dendrophilinae, Haeteriinae, Histerinae, Onthophilinae, Saprininae and Tribalinae. The relationships among early-divergent Hydrophiloidea differed between BI and MLI, and overall were unresolved or received only moderate to low nodal support. The staphylinoid families Agyrtidae, Hydraenidae and Ptiliidae were recovered as monophyletic; the latter two were sister taxa, and Staphylinidae + Silphidae was also monophyletic. Silphidae was placed within Staphylinidae in close relation to a subset of Tachyporinae. Pselaphinae and Scydmaeninae were both recovered within Staphylinidae, in accordance with recent analyses of morphological characters, although not always with recently proposed sister taxa. None of the four major groups of Staphylinidae proposed by Lawrence and Newton (1982) was recovered as monophyletic. Certain highly specialized staphyliniform habits and morphologies, such as abdominal defensive glands and reduced elytra, have arisen in parallel in separate lineages. Further, our analyses support two major transitions to an aquatic lifestyle within Staphyliniformia: once within Staphylinoidea (Hydraenidae), and once within Hydrophiloidea s.l. (Hydrophiloidea s.s.). On a smaller scale, the most common transition is from litter to subcortical or to periaquatic microhabitats and the next most common is from litter to carrion and to fungi. Overall, transitions to periaquatic microhabitats were the most numerous. The broad picture in Staphyliniformia seems to be a high level of evolutionary plasticity, with multiple possible pathways to and from many microhabitat associations, and litter as a major source microhabitat for diversification. In Scarabaeiformia, the most common transitions were from litter to foliage, with flowers to litter, litter to flowers, and litter to dung being next, and then litter to roots, logs or carrion. Litter is again the largest overall source microhabitat. The most common transitions were to foliage and flowers. It thus seems that the litter environment presents ecological and evolutionary opportunities/challenges that facilitate entry of Staphyliniformia and Scarabaeiformia into ‘new’ and different ecological adaptive zones.

A molecular phylogeny of the Chalcidoidea (Hymenoptera).

Abstract: Chalcidoidea (Hymenoptera) are extremely diverse with more than 23,000 species described and over 500,000 species estimated to exist. This is the first comprehensive phylogenetic analysis of the superfamily based on a molecular analysis of 18S and 28S ribosomal gene regions for 19 families, 72 subfamilies, 343 genera and 649 species. The 56 outgroups are comprised of Ceraphronoidea and most proctotrupomorph families, including Mymarommatidae. Data alignment and the impact of ambiguous regions are explored using a secondary structure analysis and automated (MAFFT) alignments of the core and pairing regions and regions of ambiguous alignment. Both likelihood and parsimony approaches are used to analyze the data. Overall there is no impact of alignment method, and few but substantial differences between likelihood and parsimony approaches. Monophyly of Chalcidoidea and a sister group relationship between Mymaridae and the remaining Chalcidoidea is strongly supported in all analyses. Either Mymarommatoidea or Diaprioidea are the sister group of Chalcidoidea depending on the analysis. Likelihood analyses place Rotoitidae as the sister group of the remaining Chalcidoidea after Mymaridae, whereas parsimony nests them within Chalcidoidea. Some traditional family groups are supported as monophyletic (Agaonidae, Eucharitidae, Encyrtidae, Eulophidae, Leucospidae, Mymaridae, Ormyridae, Signiphoridae, Tanaostigmatidae and Trichogrammatidae). Several other families are paraphyletic (Perilampidae) or polyphyletic (Aphelinidae, Chalcididae, Eupelmidae, Eurytomidae, Pteromalidae, Tetracampidae and Torymidae). Evolutionary scenarios discussed for Chalcidoidea include the evolution of phytophagy, egg parasitism, sternorrhynchan parasitism, hypermetamorphic development and heteronomy.

Hexamethyldisilazane - A Chemical Alternative For Drying Insects

Abstract: Two methods of chemically drying softbodied Chalcidoidea (Hymenoptera) are compared: critical-point drying (CPD) and hexamethyldisilazane (HMDS). For three groups of Eulophidae, Encyrtidae and miscellaneous Chalcidoidea, the CPD specimens were of consistently higher quality for all groups, although the overall differences between CPD and HMDS specimens were marginal. Soft-bodied insect specimens have long been the bane of systematics. Freshly killed and air-dried specimens (Fig. 1 ) undergo partial to complete collapse of body parts, whereas specimens initially preserved in EtOH fare even worse when subsequently removed from the liquid and air dried (Fig. 2). This is not only a problem of obtaining quality museum specimens but in the past has deterred some systematists from bothering with samples preserved in alcohol, such as those taken in malaise or pan traps. Critical-point drying (CPD) of specimens through a liquid CO2 intermediate (Gordh & Hall 1979) provides a means of retrieving large numbers of soft-bodied specimens from EtOH and is being widely used for some taxa, especially Chalcidoidea. The primary advantage of using CPD is little or no collapse of soft body parts, including internal muscles and nerves. Secondarily, the structure of muscles, nerve tissue and other internal body parts is maintained, allowing for later survey of these structures from museum specimens (Heraty et al. 1997). The disadvantages with the CPD are that it 1 ) is relatively expensive to buy the initial equipment ($2,000-8,000), 2) is necessary to obtain specialized CO2 tanks that must be maintained above 900 psi, 3) is labor intensive, 4) can cause abnormal swelling or occasional bursting of some body parts, and 5) may leave surface residues on specimens. Several alternatives to air drying or CPD have been proposed, some of which are freeze drying, Peldri II (Brown 1990), acetone vapor (van Noort 1995), xylene (R. Carlson pers. comm.), and hexane (D. Hawks, pers. comm.). A new chemical method involving hexamethyldisilazane (HMDS) has been proposed as a simple and cost-effective means of retrieving high-quality specimens from collections preserved in EtOH (Nation 1983, Brown 1993). Only the CPD and HMDS methods are regularly applied for the retrieval of large collections of Chalcidoidea initially preserved in alcohol, and here we compare the two methods.

Insect Mitochondrial Genomics: Implications for Evolution and Phylogeny

Abstract: The mitochondrial (mt) genome is, to date, the most extensively studied genomic system in insects, outnumbering nuclear genomes tenfold and representing all orders versus very few. Phylogenomic analysis methods have been tested extensively, identifying compositional bias and rate variation, both within and between lineages, as the principal issues confronting accurate analyses. Major studies at both inter- and intraordinal levels have contributed to our understanding of phylogenetic relationships within many groups. Genome rearrangements are an additional data type for defining relationships, with rearrangement synapomorphies identified across multiple orders and at many different taxonomic levels. Hymenoptera and Psocodea have greatly elevated rates of rearrangement offering both opportunities and pitfalls for identifying rearrangement synapomorphies in each group. Finally, insects are model systems for studying aberrant mt genomes, including truncated tRNAs and multichromosomal genomes. Greater integration of nuclear and mt genomic studies is necessary to further our understanding of insect genomic evolution.

A Total-Evidence Approach to Dating with Fossils, Applied to the Early Radiation of the Hymenoptera

Abstract: Phylogenies are usually dated by calibrating interior nodes against the fossil record. This relies on indirect methods that, in the worst case, misrepresent the fossil information. Here, we contrast such node dating with an approach that includes fossils along with the extant taxa in a Bayesian total-evidence analysis. As a test case, we focus on the early radiation of the Hymenoptera, mostly documented by poorly preserved impression fossils that are difficult to place phylogenetically. Specifically, we compare node dating using nine calibration points derived from the fossil record with total-evidence dating based on 343 morphological characters scored for 45 fossil (4-20% complete) and 68 extant taxa. In both cases we use molecular data from seven markers (∼5 kb) for the extant taxa. Because it is difficult to model speciation, extinction, sampling, and fossil preservation realistically, we develop a simple uniform prior for clock trees with fossils, and we use relaxed clock models to accommodate rate variation across the tree. Despite considerable uncertainty in the placement of most fossils, we find that they contribute significantly to the estimation of divergence times in the total-evidence analysis. In particular, the posterior distributions on divergence times are less sensitive to prior assumptions and tend to be more precise than in node dating. The total-evidence analysis also shows that four of the seven Hymenoptera calibration points used in node dating are likely to be based on erroneous or doubtful assumptions about the fossil placement. With respect to the early radiation of Hymenoptera, our results suggest that the crown group dates back to the Carboniferous, ∼309 Ma (95% interval: 291-347 Ma), and diversified into major extant lineages much earlier than previously thought, well before the Triassic. (Bayesian inference; fossil dating; morphological evolution; relaxed clock; statistical phylogenetics.)

CONTROL OF MOTH PESTS BY MATING DISRUPTION: Successes and Constraints

Abstract: Male moths generally find their mates by following the females' pheromone plume to its source. A formulated copy of this message is used to regulate mating of many important pests, including the pink bollworm (Pectinophora gossypiella), the oriental fruit moth (Grapholita molesta), and the tomato pinworm (Keiferia lycopersicella). How synthetic disruptant interrupts normal orientation is uncertain, but the most probable mechanisms invoke adaptation and habituation, competition between point sources of formulation and females, and a camouflage of a female's pheromone plume by the formulation. The efficacy of this technology is related principally to the motility of mated females into the area to be managed, the initial population levels of the pest, and the release characteristics of the formulation. In most cases, implementation of this technology necessitates a sophisticated monitoring and management program. Area-wide management schemes are ideal vehicles for using disruptants. Future acceptance of this...

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

Abstract: © 2015 The Authors. Systematic Entomology published by John Wiley & Sons Ltd on behalf of Royal Entomological Society This is an open access article under the terms of the Creative Commons AttributionߚNonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.