Tip-dated phylogeny of whirligig beetles reveals ancient lineage surviving on Madagascar

Proteomic diversification of spermatostyles among six species of whirligig beetles

Seminal fluid protein composition is complex and commonly assumed to be rapidly divergent due to functional interactions with both sperm and the female reproductive tract (FRT), both of which evolve rapidly. In addition to sperm, seminal fluid may contain structures, such as mating plugs and spermatophores. Here, we investigate the evolutionary diversification of a lesser-known ejaculate structure: the spermatostyle, which has independently arisen in several families of beetles and true bugs. We characterized the spermatostyle proteome, in addition to spermatostyle and FRT morphology, in six species of whirligig beetles (family Gyrinidae). Spermatostyles were enriched for proteolytic enzymes, and assays confirmed they possess proteolytic activity. Sperm-leucylaminopeptidases (S-LAPs) were particularly abundant, and their localization to spermatostyles was confirmed by immunohistochemistry. Although there was evidence for functional conservation of spermatostyle proteomes across species, phylogenetic regressions suggest evolutionary covariation between protein composition and the morphology of both spermatostyles and FRTs. We postulate that S-LAPs (and other proteases) have evolved a novel structural role in spermatostyles and discuss spermatostyles as adaptations for delivering male-derived materials to females.

Early evolution of Anamorphidae (Coleoptera: Coccinelloidea): the oldest known anamorphid beetles from Upper Cretaceous amber of northern Myanmar and the first report of potential glandular pores in the family

In order to place newly discovered fossil taxa (Palaeosymbius gen. nov. with P. groehni and P. mesozoicus spp. nov.) from the mid-Cretaceous amber from northern Myanmar, we investigated the relations of extant and extinct lineages of the coccinellid group of Coccinelloidea with emphasis on the family Anamorphidae. We assembled a taxonomic sampling of 34 taxa, including 15 genera and 19 species of Anamorphidae, the most comprehensive sampling of Anamorphidae at the generic level in a phylogenetic analysis. A morphological dataset of 47 characters was built as well as a molecular alignment of 7140 bp including fragments of eight genes (12S, 16S, 18S, 28S, COI, COII, H3 and CAD). Five anamorphid and one endomychid species were sequenced for the first time and added to the dataset. We performed parsimony-based analysis of the morphological dataset and Bayesian inference analysis of the combined matrix (morphological plus molecular data). Our results confirm that Palaeosymbius belongs to Anamorphidae and represents the oldest known member of this family so far. Among Anamorphidae, Symbiotes (with extant and known Eocene species) was recovered as the most probable closest relative of Palaeosymbius. Our morphological studies additionally revealed the presence of probable glandular openings in the anterolateral corners of the pronotal margins in Asymbius sp. and Anamorphus sp., representing the first report of secretory openings in the family Anamorphidae. Similar openings are found in other cucujiform beetles such as Cryptophagidae and Boganiidae with possible defensive purposes.

Effects of climate and environmental heterogeneity on the phylogenetic structure of regional angiosperm floras worldwide

The tendency of species to retain ancestral ecological distributions (phylogenetic niche conservatism) is thought to influence which species from a species pool can persist in a particular environment. Thus, investigating the relationships between measures of phylogenetic structure and environmental variables at a global scale can help understand the variation in species richness and phylogenetic structure in biological assemblages across the world. Here, we analyze a comprehensive data set including 341,846 species in 391 angiosperm floras worldwide to explore the relationships between measures of phylogenetic structure and environmental variables for angiosperms in regional floras across the world and for each of individual continental (biogeographic) regions. We find that the global phylogenetic structure of angiosperms shows clear and meaningful relationships with environmental factors. Current climatic variables have the highest predictive power, especially on phylogenetic metrics reflecting recent evolutionary relationships that are also related to current environmental heterogeneity, presumably because this favors plant speciation in various ways. We also find evidence that past climatic conditions, and particularly refugial conditions, play an important role in determining the phylogenetic structure of regional floras. The relationships between environmental conditions and phylogenetic metrics differ between continents, reflecting the different evolutionary histories of their floras.

Morphology of the Female and Male Reproductive Tracts and More Data on the Spermatostyle in the Brazilian Gyretes sp. (Coleoptera, Adephaga, Gyrinidae)

We investigated the male and female reproductive tracts of Gyretes sp. with light and transmission electron microscopies. The male has a pair of testes with a single coiled follicle, followed by short efferent ducts, which have a similar shape and diameter to the testes. Long ducts (epididymides) with differential epithelium open in a pair of long vasa deferentia that lead to the accessory glands. Glycoprotein secretions from the vas deferens epithelium constitute the spermatostyle for spermatozoa aggregation. The female has numerous ovarioles per ovary, a coiled fertilization duct, an accessory gland, and an elongated vagina. Spermatozoa are stored as unaggregated cells in the fertilization duct. In Gyrinidae, the testes and accessory glands show diverse shapes, and the female sperm storage organs vary in shape, size, and type and may play a role in the interaction with sperm aggregates. Testes with a single follicle and vasa deferentia opening in the accessory glands of Gyretes sp. are features shared with other Gyrinidae and other Adephaga. We proposed adding this latter trait to characterize this suborder of beetles. The morphology of the reproductive organs in both sexes contributes to comparative analyses and knowledge of the reproductive biology of Gyretes and may provide additional features for systematics.

Estimating the Age of Poorly Dated Fossil Specimens and Deposits Using a Total-Evidence Approach and the Fossilized Birth-Death Process

Bayesian total-evidence approaches under the fossilized birth-death model enable biologists to combine fossil and extant data while accounting for uncertainty in the ages of fossil specimens, in an integrative phylogenetic analysis. Fossil age uncertainty is a key feature of the fossil record as many empirical data sets may contain a mix of precisely dated and poorly dated fossil specimens or deposits. In this study, we explore whether reliable age estimates for fossil specimens can be obtained from Bayesian total-evidence phylogenetic analyses under the fossilized birth-death model. Through simulations based on the example of the Baltic amber deposit, we show that estimates of fossil ages obtained through such an analysis are accurate, particularly when the proportion of poorly dated specimens remains low and the majority of fossil specimens have precise dates. We confirm our results using an empirical data set of living and fossil penguins by artificially increasing the age uncertainty around some fossil specimens and showing that the resulting age estimates overlap with the recorded age ranges. Our results are applicable to many empirical data sets where classical methods of establishing fossil ages have failed, such as the Baltic amber and the Gobi Desert deposits. [Bayesian phylogenetic inference; fossil age estimates; fossilized birth-death; Lagerstätte; total-evidence.].

The Naucoridae (Heteroptera: Nepomorpha) of Madagascar, with revisions of Temnocoris and Tsingala (Laccocorinae)

The island nation of Madagascar was surveyed extensively through a series of expeditions to determine the fauna of Naucoridae. Previously, 17 species in four genera had been reported from the country. All taxa previously recorded from Madagascar were re-collected, with the exception of three species, Macrocoris flavicollis Signoret, Temnocoris starmuhlneri Poisson, and Tsingala nossibeanus (Bergroth). Macrocoris flavicollis is removed from the list of species occurring in Madagascar. Within Laccocorini (Laccocorinae), a new genus, Gonioathrixn.gen. is described; Temnocoris and Tsingala are revised; three new species are described in Temnocoris (T. leachin.sp., T. montandonin.sp., T. poissonin.sp.) and four in Tsingala (T. angulatan.sp., T. latiforman.sp., T. spatulatan.sp., T. trilobatan.sp.). Lectotypes are designated for Afronaucoris madagascariensis (Montandon), Tsingala humeralis (Signoret), and T. naucoroides (Montandon). In Macrocorinae, a new species of Macrocoris, M. namoronan.sp., from Ranomafana National Park is described. These taxonomic actions bring the total for the country to five genera and 25 species. Distributions, habitat associations, and a key to the species are presented.

Overcoming Drag at the Water-Air Interface Constrains Body Size in Whirligig Beetles

Whirligig beetles (Coleoptera: Gyrinidae) are among the best swimmers of all aquatic insects. They live mostly at the water’s surface and their capacity to swim fast is key to their survival. We present a minimal model for the viscous and wave drags they face at the water’s surface and compare them to their thrust capacity. The swimming speed accessible is thus derived according to size. An optimal size range for swimming at the water’s surface is observed. These results are in line with the evolutionary trajectories of gyrinids which evolved into lineages whose members are a few milimeter’s long to those with larger-sized genera being tens of millimeters in length. The size of these beetles appears strongly constrained by the fluid mechanical laws ruling locomotion and adaptation to the water-air interface.

Burmese amber reveals a new stem lineage of whirligig beetle (Coleoptera: Gyrinidae) based on the larval stage

Burmese amber is well known for preserving unique extinct lineages of insects. Here, we describe a new fossil beetle in its larval stage from Burmese amber. Bayesian and parsimony phylogenetic analysis of 50 morphological characters support this fossil as being sister to both the tribes Dineutini and Orectochilini, representing an extinct stem lineage in Gyrininae. It is described here as a new genus and species of whirligig beetle, Chimerogyrus gigagalea gen. & sp. nov., a taxon that preserves remarkable intermediate features between the whirligig beetle tribe Gyrinini and the crown Orectochilini and Dineutini. This new taxon preserves key features for studying the evolution of characters within the larval stage of the Gyrinidae and highlights the importance of Burmese amber for preserving both stem and crown lineages present during the mid-Cretaceous, before the end-Cretaceous mass extinction event.

Unravelling the mystery of "Madagascar copal": Age, origin and preservation of a Recent resin

The loss of biodiversity during the Anthropocene is a constant topic of discussion, especially in the top biodiversity hotspots, such as Madagascar. In this regard, the study of preserved organisms through time, like those included in "Madagascar copal", is of relevance. “Madagascar copal" originated from the leguminous tree Hymenaea verrucosa, which produced and produces resin abundantly. In the last 20 years, interest has focused on the scientific study of its biological inclusions, mainly arthropods, described in dozens of publications. The age and origin of the deposits of "Madagascar copal" have not yet been resolved. Our objectives are to determine its age and geographical origin, and thus increase its scientific value as a source of biological/palaeobiological information. Although Hymenaea was established in Madagascar during the Miocene, we did not find geological deposits of copal or amber in the island. It is plausible that the evolution of those deposits was negatively conditioned by the type of soil, by the climate, and by the development of soil/litter microorganisms, which inhibit preservation of the resin pieces in the litter and subsoil over 300 years. Our results indicate that "Madagascar copal" is a Recent resin, up to a few hundred years old, that originated from Hymenaea trees growing in the lowland coastal forests, one of the most endangered ecosystems in the world. The included and preserved biota is representative of that ecosystem today and during historical times. Inclusions in this Recent resin do not have the palaeontological significance that has been mistakenly attributed to them, but they do have relevant implications for studies regarding Anthropocene biodiversity loss in this hottest hotspot.

Ultraconserved element (UCE) probe set design: Base genome and initial design parameters critical for optimization

Targeted capture and enrichment approaches have proven effective for phylogenetic study. Ultraconserved elements (UCEs) in particular have exhibited great utility for phylogenomic analyses, with the software package phyluce being among the most utilized pipelines for UCE phylogenomics, including probe design. Despite the success of UCEs, it is becoming increasing apparent that diverse lineages require probe sets tailored to focal taxa in order to improve locus recovery. However, factors affecting probe design and methods for optimizing probe sets to focal taxa remain underexplored. Here, we use newly available beetle (Coleoptera) genomic resources to investigate factors affecting UCE probe set design using phyluce. In particular, we explore the effects of stringency during initial design steps, as well as base genome choice on resulting probe sets and locus recovery. We found that both base genome choice and initial bait design stringency parameters greatly alter the number of resultant probes included in final probe sets and strongly affect the number of loci detected and recovered during in silico testing of these probe sets. In addition, we identify attributes of base genomes that correlated with high performance in probe design. Ultimately, we provide a recommended workflow for using phyluce to design an optimized UCE probe set that will work across a targeted lineage, and use our findings to develop a new, open‐source UCE probe set for beetles of the suborder Adephaga.

Molecular phylogeny and diversification timing of the Nemouridae family (Insecta, Plecoptera) in the Japanese Archipelago

The generation of the high species diversity of insects in Japan was profoundly influenced by the formation of the Japanese Archipelago. We explored the species diversification and biogeographical history of the Nemouridae Billberg, 1820 family in the Japanese Archipelago using mitochondrial DNA and nuclear DNA markers. We collected 49 species among four genera: Indonemoura Baumann, 1975; Protonemura Kempny, 1898; Amphinemura, Ris 1902 and Nemoura Latreille, 1796 in Japan, China, South Korea and North America. We estimated their divergence times-based on three molecular clock node calibrations-using Bayesian phylogeography approaches. Our results suggested that Japanese Archipelago formation events resulted in diversification events in the middle of the Cretaceous (<120 Ma), speciation in the Paleogene (<50 Ma) and intra-species diversification segregated into eastern and western Japan of the Fossa Magna region at late Neogene (20 Ma). The Indonemoura samples were genetically separated into two clades-that of Mainland China and that of Japan. The Japanese clade clustered with the Nemouridae species from North America, suggesting the possibility of a colonisation event prior to the formation of the Japanese Archipelago. We believe that our results enhanced the understanding both of the origin of the species and of local species distribution in the Japanese Archipelago.

Water Beetles as Models in Ecology and Evolution

Beetles have colonized water many times during their history, with some of these events involving extensive evolutionary radiations and multiple transitions between land and water. With over 13,000 described species, they are one of the most diverse macroinvertebrate groups in most nonmarine aquatic habitats and occur on all continents except Antarctica. A combination of wide geographical and ecological range and relatively accessible taxonomy makes these insects an excellent model system for addressing a variety of questions in ecology and evolution. Work on water beetles has recently made important contributions to fields as diverse as DNA taxonomy, macroecology, historical biogeography, sexual selection, and conservation biology, as well as predicting organismal responses to global change. Aquatic beetles have some of the best resolved phylogenies of any comparably diverse insect group, and this, coupled with recent advances in taxonomic and ecological knowledge, is likely to drive an expansion of studies in the future.

Whirling in the late Permian: ancestral Gyrinidae show early radiation of beetles before Permian-Triassic mass extinction

Background

Gyrinidae are a charismatic group of highly specialized beetles, adapted for a unique lifestyle of swimming on the water surface. They prey on drowning insects and other small arthropods caught in the surface film. Studies based on morphological and molecular data suggest that gyrinids were the first branch splitting off in Adephaga, the second largest suborder of beetles. Despite its basal position within this lineage and a very peculiar morphology, earliest Gyrinidae were recorded not earlier than from the Upper Triassic.

Results

Tunguskagyrus. with the single species Tunguskagyrus planus is described from Late Permian deposits of the Anakit area in Middle Siberia. The genus is assigned to the stemgroup of Gyrinidae, thus shifting back the minimum age of this taxon considerably: Tunguskagyrus demonstrates 250 million years of evolutionary stability for a very specialized lifestyle, with a number of key apomorphies characteristic for these epineuston predators and scavengers, but also with some preserved ancestral features not found in extant members of the family. It also implies that major splitting events in this suborder and in crown group Coleoptera had already occurred in the Permian. Gyrinidae and especially aquatic groups of Dytiscoidea flourished in the Mesozoic (for example Coptoclavidae and Dytiscidae) and most survive until the present day, despite the dramatic “Great Dying” – Permian-Triassic mass extinction, which took place shortly (in geological terms) after the time when Tunguskagyrus lived.

Conclusions

Tunguskagyrus confirms a Permian origin of Adephaga, which was recently suggested by phylogenetic “tip-dating” analysis including both fossil and Recent gyrinids. This also confirms that main splitting events leading to the “modern” lineages of beetles took place before the Permian-Triassic mass extinction. Tunguskagyrus shows that Gyrinidae became adapted to swimming on the water surface long before Mesozoic invasions of the aquatic environment took place (Dytiscoidea). The Permian origin of Gyrinidae is consistent with a placement of this highly derived family as the sister group of all remaining adephagan groups, as suggested based on morphological features of larvae and adults and recent analyses of molecular data.

West meets East: How do rainforest beetles become circum-Pacific? Evolutionary origin of Callipogon relictus and allied species (Cerambycidae: Prioninae) in the New and Old Worlds

The longhorn beetle genus Callipogon Audinet-Serville represents a small group of large wood-boring beetles whose distribution pattern exhibits a unique trans-Pacific disjunction between the East Asian temperate rainforest and the tropical rainforest of the Neotropics. To understand the biogeographic history underlying this circum-Pacific disjunct distribution, we reconstructed a molecular phylogeny of the subfamily Prioninae with extensive sampling of Callipogon using multilocus sequence data of 99 prionine and four parandrine samples (ingroups), together with two distant outgroup species. Our sampling of Callipogon includes 18 of the 24 currently accepted species, with complete representation of all species in our focal subgenera. Our phylogenetic analyses confirmed the purported affinity between the Palearctic Callipogon relictus and its Neotropical congeners. Furthermore, based on molecular dating under the fossilized birth-death (FBD) model with comprehensive fossil records and probabilistic ancestral range reconstructions, we estimated the crown group Callipogon to have originated in the Paleocene circa 60 million years ago (Ma) across the Neotropics and Eastern Palearctics. The divergence between the Palearctic C. relictus and its Neotropical congeners is explained as the result of a vicariance event following the demise of boreotropical forest across Beringia at the Eocene-Oligocene boundary. As C. relictus represents the unique relictual species that evidentiates the lineage's expansive ancient distribution, we evaluated its conservation importance through species distribution modelling. Though we estimated a range expansion for C. relictus by 2050, we emphasize a careful implementation of conservation programs towards the protection of primary forest across its current habitats, as the species remains highly vulnerable to habitat disturbance.