Sympatric host-associated genetic differentiation is a prominent pattern that could lead to speciation. In insects, there are numerous examples of host-associated differentiation among herbivores that prefer different plants, and parasitoids that prefer different hosts, but few examples for specialist predators. We developed new microsatellite loci for two species of silver fly, Leucotaraxis argenticollis (Zetterstedt) and L. piniperda (Malloch) (Diptera: Chamaemyiidae), being evaluated as biological control agents for the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), in eastern North America where it is a nonnative pest. We obtained DNA from specimens of both fly species feeding on native A. tsugae in western North America, as well as on other western and eastern adelgid species. We performed population genetic analyses using the new loci and DNA barcode sequences. Our results confirmed east–west allopatric divergence and uncovered nested genetic differentiation associated with different adelgid prey species and their host plants in western North America for both species of silver flies. For both species, there is also evidence for a longer history of diversification in the west, with ancestral specialization of feeding on pine adelgids, which was retained after range expansion to the east. More recently, divergence to feeding on new adelgid prey species occurred in the west. Our findings are consistent with the hypothesis that host-alternating life cycles in Adelgidae may provide temporary escape from specialist predators. We discuss the implications for biological control efficacy and potential for lineage hybridization as western flies are released in the east to control A. tsugae.

Spiders of the genus Troglohyphantes (Araneae: Linyphiidae) exemplify one of the largest subterranean adaptive radiation across European mountain ranges, counting over 130 species and representing about one fifth of total species richness of cave spiders in Europe. Despite the emerging potential of Troglohyphantes as a biogeographical model, no attempt has been made to reconstruct the geological events underlying the current distribution patterns of the genus. By coupling traditional taxonomy with target gene sequence data and comparative functional trait analyses, we describe a new species of Troglohyphantes, the first reported from the island of Corsica (France). The species is characterized by a high level of subterranean adaptation and distinct morphological affinities with geographically distant congenerics. By means of time-stamped phylogenies, we tested contrasting hypotheses about the origin of the new species. The most parsimonious explanation suggests that the species diverged from an ancestral group of species originating in the Adriatic plate in the lower Miocene (∼19 Ma), colonizing Corsica from the east. In the absence of relevant fossil records, the well-known geochronology of Corsica and the Western Mediterranean basin can be used in future studies to reconstruct the biogeography of the whole genus and for inferring the timeline of its diversification.

Graphical Abstract

The tribe Noctuini is comprised over 520 species; many are economically important species that impact human agriculture. Despite their diversity and relevance, relationships of Noctuini have been difficult to resolve. There have been extensive morphological revisions of some of these taxa (e.g., Agrotis Ochsenheimer, Euxoa Hübner); however, there are no studies that focus exclusively on the phylogenetic relationships of the Noctuini. Currently, Noctuini are separated into 2 subtribes, Agrotina and Noctuina. In this study, we tested previous classification schemes with 2 analyses. The total evidence analysis utilized 3 loci for 3 outgroup taxa and 54 noctuine species. Using museum specimens, we collected data from cytochrome oxidase I (COI), Dopa Decarboxylase (DDC), and Elongation factor 1-α (EF1-α) to generate a dataset of 1,378 base pairs (bp) for a total evidence approach. We also used previously published COI sequences for 626 species, resulting in a matrix of 690 bp, termed “the barcode analysis.” We used both Maximum Likelihood and Bayesian approaches for the total evidence analysis, and ML for the barcode analysis. In both sets of results, we found equivocal support for monophyletic Agrotina and Noctuina. We found strong support for smaller, well-described genera (e.g., Spaelotis), but poor support for large genera such as Euxoa, Feltia Walker, and Agrotis. It is likely that a combination of limited taxon/gene sampling, limited gene choice, and the rapid evolution of these species resulted in a lack of phylogenetic resolution in the total evidence topologies. Based on these results, we recommend increased taxon sampling and inclusion of loci that target these rapidly evolving lineages to achieve a better understanding of the phylogeny of Noctuini and its genera.

The use of gDNAs isolated from museum specimens for high throughput sequencing, especially targeted sequencing in the context of phylogenetics, is a common practice. Yet, little understanding has been focused on comparing the quality of DNA and results of sequencing museum DNAs. Dragonflies and damselflies are ubiquitous in freshwater ecosystems and are commonly collected and preserved insects in museum collections hence their use in this study. However, the history of odonate preservation across time and museums has resulted in wide variability in the success of viable DNA extraction, necessitating an assessment of their usefulness in genetic studies. Using Anchored Hybrid Enrichment probes, we sequenced DNA from samples at 2 museums, 48 from the American Museum of Natural History (AMNH) in NYC, USA and 46 from the Naturalis Biodiversity Center (RMNH) in Leiden, Netherlands ranging from global collection localities and across a 120-year time span. We recovered at least 4 loci out of an >1,000 locus probe set for all samples, with the average capture being ∼385 loci (539 loci on average when a clade of ambiguous taxa omitted). Neither specimen age nor size was a good predictor of locus capture, but recapture rates differed significantly between museums. Samples from the AMNH had lower overall locus capture than the RMNH, perhaps due to differences in specimen storage over time.