The evolution of ants (Hymenoptera: Formicidae) is increasingly well-understood due to recent phylogenetic analyses, along with estimates of divergence times and diversification rates. Yet, leading hypotheses regarding the ancestral habitat of ants conflict with new findings that early ant lineages are cryptic and subterranean. Where the ants evolved, in respect to habitat, and how habitat shifts took place over time have not been formally tested. Here, we reconstruct the habitat transitions of crown-group ants through time, focusing on where they nest and forage (in the canopy, litter, or soil). Based on ancestral character reconstructions, we show that in contrast to the current consensus based on verbal arguments that ants evolved in tropical leaf litter, the soil is supported as the ancestral stratum of all ants. We also find subsequent movements up into the litter and, in some cases, into the canopy. Given the global importance of ants, because of their diversity, ecological influence and status as the most successful eusocial lineage on Earth, understanding the early evolution of this lineage provides insight into the factors that made this group so successful today.

Targeted enrichment of ultraconserved elements (UCEs) has emerged as a promising tool for inferring evolutionary history in many taxa, with utility ranging from phylogenetic and biogeographic questions at deep time scales to population level studies at shallow time scales. However, the methodology can be daunting for beginners. Our goal is to introduce UCE phylogenomics to a wider audience by summarizing recent advances in arthropod research, and to familiarize readers with background theory and steps involved. We define terminology used in association with the UCE approach, evaluate current laboratory and bioinformatic methods and limitations, and, finally, provide a roadmap of steps in the UCE pipeline to assist phylogeneticists in making informed decisions as they employ this powerful tool. By facilitating increased adoption of UCEs in phylogenomics studies that deepen our comprehension of the function of these markers across widely divergent taxa, we aim to ultimately improve understanding of the arthropod tree of life.

While some relationships in phylogenomic studies have remained stable since the Sanger sequencing era, many challenging nodes remain, even with genome-scale data. Incongruence or lack of resolution in the phylogenomic era is frequently attributed to inadequate data modeling and analytical issues that lead to systematic biases. However, few studies investigate the potential for random error or establish expectations for the level of resolution achievable with a given empirical data set and integrate uncertainties across methods when faced with conflicting results. Ants are the most species-rich lineage of social insects and one of the most ecologically important terrestrial animals. Consequently, ants have garnered significant research attention, including their systematics. Despite this, there has been no comprehensive genus-level phylogeny of the ants inferred using genomic data that thoroughly evaluates both signal strength and incongruence. In this study, we provide insight into and quantify uncertainty across the ant tree of life by utilizing the most taxonomically comprehensive ultraconserved elements data set of ants to date, including 277 (81%) of recognized ant genera from all 16 extant subfamilies, and representing over 98% of described species. We use simulations to establish expectations for resolution, identify branches with less-than-expected concordance, and dissect the effects of data and model selection on recalcitrant nodes. Simulations show that hundreds of loci are needed to resolve recalcitrant nodes on our genus-level ant phylogeny. This demonstrates the continued role of random error in phylogenomic studies. Our analyses provide a comprehensive picture of support and incongruence across the ant phylogeny, while offering a more nuanced depiction of uncertainty and significantly expanding generic sampling. We use a consensus approach to integrate uncertainty across different analyses and find that assumptions about root age exert substantial influence on divergence dating. Our results suggest that advancing the understanding of ant phylogeny will require not only more data but also more refined phylogenetic models. We also provide a workflow for identifying under-supported nodes in concatenation analyses, outline a pragmatic way to reconcile conflicting results in phylogenomics, and introduce a user-friendly locus selection tool for divergence dating.

Clarifying the population structure and introduction history of non-native species is essential to preventing and mitigating effects of invasion, yet the invasion history of many long-established non-native species remain poorly understood. This study characterized the population structure of one of the most commonly encountered urban ants in North America using public participant-collected specimens and double-digest restriction-site associated DNA sequencing (ddRADseq). Based on this genomic approach we confirm the identity of populations ranging across the continent as Tetramorium immigrans Santschi, and report low genetic diversity across its range, suggesting that this entire population resulted from the establishment of one single, or a few closely related ant colonies, approximately 200 years ago. The absence of strong population structure suggests that this ant's spread across North America has been repeatedly aided by human-assisted dispersal. We find no evidence of inbreeding in T. immigrans; this contrasts with the inbreeding and unicoloniality of many other invasive ants. These results demonstrate how collections-based public participatory science and emerging high-throughput sequencing techniques each have the potential to vastly improve the amount of data available to researchers. Together, these techniques can be deployed to address ecological and evolutionary questions, including questions about invasion biology, in non-model organisms. We suggest that this model is particularly well-suited for research on common taxa that are ecologically important but poorly understood.

Assembling and curating specimen collections is a valuable educational exercise that integrates subject-specific skills such as field collection, curation, identification, organization, and interpretation of relationships. Collection projects have been used primarily in face-to-face classes, but they can be readily adapted for distance education. The primary challenges to using collection projects in distance education center on two concerns: (1) whether distance students learn as much as their face-to-face peers and (2) whether academic dishonesty occurs more often in distance education than face to face. This study addressed both concerns by assessing learning outcomes in two entomology courses with both face-to-face and distance sections and evaluating the frequency of specimen-based plagiarism (submitting specimens collected by someone else). An ungraded survey testing students’ insect identification knowledge found equivalent learning outcomes in face-to-face and distance classes. Insect collections were monitored for plagiarized (resubmitted or purchased) specimens in a 5-year “mark-release-recapture” investigation. Academic dishonesty was detected in fewer than 2% of collections; cheating was more than 12 times more likely in distance than in face-to-face classes. This study’s findings raise the possibility that distance learning assessments can be artificially inflated by cheating, suggesting that evaluations of distance learning should be considered in light of academic dishonesty. These results highlight the benefits and challenges of collections as teaching tools in distance education and underscore the need for instructors to be vigilant about academic integrity.