Anna K. Childers

As eukaryotic genomes continue to be sequenced, assembled, and annotated at decreasing cost and increasing rate, it is important that basic notification of the availability of these genomes, along with essential information about them, be made available to the community. One way of doing this is through publication of a “genome report,” a short article format that several journals have established. Here, we provide a brief guide to the genome report and its main components, with recommendations for authors, reviewers, and publishers of such reports.

Diabrotica undecimpunctata ssp. howardi, the southern corn rootworm or eastern 12-spotted cucumber beetle, is a generalist insect herbivore that causes damage and yield loss to several crops in North America, including maize. Unresolved phylogenetic relationships within and among D. undecimpunctata subspecies are impacting current quarantine policies. We report the chromosome-level haploid genome assembly, icDiaUnde3, constructed using HiFi and Hi-C read data from a single male D. undecimpunctata collected and identified as subspecies howardi based on geographic location and morphology. The primary 1.74 Gbp assembly contains 11 chromosome-length scaffolds representing 9 autosomes, a single X chromosome, and a supernumerary (B) chromosome (scaffold N50 = 162.8 Mb and L50 = 5). Ab initio and evidence-based structural reference sequence (RefSeq) annotations predicted 18,959 protein-coding genes, in which 99.2% of the 1,367 Benchmark Universal Single-Copy Orthologs from Insecta were complete. Repeat elements occupy 1.26 Gbp (72.33%) of the icDiaUnde3 assembly, with nearly 36% predicted to be retroelements. Alignment of whole chromosomes from icDiaUnde3 with those previously assembled from Diabrotica spp. predicted 2 and 6 autosomal inversions with D. balteata and D. virgifera, respectively. The mitochondrial genome had an annotated gene order and orientation conserved among beetles. The icDiaUnde3 reference genome assembly is a vital resource for taxonomic, comparative, and functional studies to enhance sustainable crop production.

Locust swarming, one of nature's most spectacular examples of a repeated emergent polyphenism, has long been suspected to rely on conserved "swarming genes" or shared genomic features. By applying a model-clade approach comparing six species that vary in their degrees of plasticity and collective behavior, we show that the evolution of swarming locusts is not driven by shared genomic features or a universal set of swarming genes. In contrast, we find that this phenomenon evolved through flexible regulatory architectures, in which the degree of behavioral plasticity directly correlates with the total scale of density-responsive gene expression. While different locust species recruit largely non-overlapping gene sets to achieve the same syndrome, these divergent molecular machineries converge on similar higher-level biological functions. Thus, multiple molecular pathways achieve locust swarming, challenging the preconceived notion about the genetic prerequisites to transition from solitary to collective states. Further, we establish that a complex syndrome such as locust swarming emerges through modular regulatory systems that can be amplified, modified, or attenuated across the tree of life.

In recent years, many high-quality reference genome sequences for arthropod species have been generated. Although most genome papers describe their protocols and metrics, no consensus exists on the data that should be included in genome reports. Here, we review current standards across seven key stages of an arthropod genome project (budgeting, sourcing and vouchering, sample preparation and sequencing, genome assembly, analysis reproducibility, databasing, and genome annotation) and identify persistent gaps in standards as well as their implementation. To assess current standards reporting in the community, we surveyed 100 arthropod genome papers published in 2024. The use of long reads to assemble highly contiguous arthropod genomes is now standard practice when adequate input DNA is available, and basic assembly contiguity and conserved gene content statistics are consistently reported. However, there is less standardization in pre- and post-assembly procedures and metrics. When comparing Darwin Tree of Life (DToL) genome notes to other journals, publications from the latter group were less likely to describe compliance with ethical collection practices, sample vouchering, post-assembly curation steps, and assembly quality metrics beyond basic contiguity and completeness values. Genome annotation practices are highly variable: some genome note formats do not explicitly require annotation, and while the reporting rate of protein-coding gene annotations is higher in non-DToL publications, the submission rate of annotations to centralized sequence databases is much lower. Our findings highlight critical opportunities to harmonize reporting standards and promote their dissemination, ensuring that future arthropod genomes are both comparable and maximally reusable for large-scale comparative and applied research.

The pecan weevil, Curculio caryae (Horn), is an obligate feeder of pecan and native hickory trees (genus Carya ) throughout North America. Subsequently it is a significant agricultural pest in pecan orchards. In this study, we present a reference quality genome using deep-coverage, ~40x PacBio HiFi genome sequence reads, and chromatin confirmation, Hi-C, scaffolding. The final genome assembly is approximately 2.2 Gb, which was confirmed by flow cytometry. The primary genome scaffolds have an N50 of 132 Mb and a BUSCO completeness of 95.4% [S:94.3%, D:1.1%]. Furthermore, we employed PacBio long-read RNA, Iso-seq, for de novo gene annotation, in conjunction with InterProscan to identify approximately 19,000 protein coding genes. Repeat content is extensive, contributing at least >80% of the total genome. This data set provides a valuable resource for comparative genomics and evolutionary studies of an economically impactful group of insect pests that currently lack extensive genomic resources.

The soft tick family Argasidae contains vectors of medical and veterinary importance, but few molecular resources are available compared to hard ticks (Ixodidae). One example is Ornithodoros turicata, a recognized vector of Borrelia turicatae, causal agent of human relapsing fever, and a putative vector of African swine fever virus. To address the current lack of molecular resources for the Argasidae, we generated a chromosome-level genome assembly for O. turicata using PacBio sequencing in conjunction with an Illumina Hi-C library. The resulting reference genome has a total of 1.1 Gb in length and was assembled into 10 chromosomes and 368 unplaced scaffolds, an N50 of 2.7 Mb, and a QV score of 43.58. The orthology analysis indicated high-quality with a 97.8% BUSCO completeness score and 36,149 annotated genes. 33% of the genome was identified as repeats and masked. The generation of the first soft tick reference genome establishes a basis for future studies to utilize genomic tools to support vector-borne disease management.

The Earth BioGenome Project has the extremely ambitious goal of generating, at scale, high-quality reference genomes across the entire Tree of Life. Currently in its first phase, the project is targeting family-level representatives and is progressing rapidly. Here we outline recommended standards and considerations in sample acquisition and processing for those involved in biodiverse reference genome creation. These standards and recommendations will evolve with advances in related processes. Additionally, we discuss the challenges raised by the ambitions for later phases of the project, highlighting topics related to sample collection and processing that require further development.

The expansion of agriculture is responsible for the mass conversion of biologically diverse natural environments into managed agroecosystems dominated by a handful of genetically homogeneous crop species. Agricultural ecosystems typically have very different abiotic and ecological conditions from those they replaced and create potential niches for those species that are able to exploit the abundant resources offered by crop plants. While there are well-studied examples of crop pests that have adapted into novel agricultural niches, the impact of agricultural intensification on the evolution of crop mutualists such as pollinators is poorly understood. We combined genealogical inference from genomic data with archaeological records to demonstrate that the Holocene demographic history of a wild specialist pollinator of Cucurbita (pumpkins, squashes, and gourds) has been profoundly impacted by the history of agricultural expansion in North America. Populations of the squash bee Eucera pruinosa experienced rapid growth in areas where agriculture intensified within the past 1,000 y, suggesting that the cultivation of Cucurbita in North America has increased the amount of floral resources available to these bees. In addition, we found that roughly 20% of this bee species’ genome shows signatures of recent selective sweeps. These signatures are overwhelmingly concentrated in populations from eastern North America where squash bees were historically able to colonize novel environments due to human cultivation of Cucurbita pepo and now exclusively inhabit agricultural niches. These results suggest that the widespread cultivation of crops can prompt adaptation in wild pollinators through the distinct ecological conditions imposed by agricultural environments.

Long-read sequencing has revolutionized genome assembly, yielding highly contiguous, chromosome-level contigs. However, assemblies from some third generation long read technologies, such as Pacific Biosciences (PacBio) Continuous Long Reads (CLR), have a high error rate. Such errors can be corrected with short reads through a process called polishing. Although best practices for polishing non-model de novo genome assemblies were recently described by the Vertebrate Genome Project (VGP) Assembly community, there is a need for a publicly available, reproducible workflow that can be easily implemented and run on a conventional high performance computing environment. Here, we describe polishCLR (https://github.com/isugifNF/polishCLR), a reproducible Nextflow workflow that implements best practices for polishing assemblies made from CLR data. PolishCLR can be initiated from several input options that extend best practices to suboptimal cases. It also provides re-entry points throughout several key processes, including identifying duplicate haplotypes in purge_dups, allowing a break for scaffolding if data are available, and throughout multiple rounds of polishing and evaluation with Arrow and FreeBayes. PolishCLR is containerized and publicly available for the greater assembly community as a tool to complete assemblies from existing, error-prone long-read data.