Pearse, A. R. | bioRxiv Science

bioRxiv2026

Temporal changes in genetic variation during the invasion of Lygodium japonicum in North America

Premise of the study. Invasive species are now widespread and have detrimental ecological and economic impacts. They also offer opportunities to investigate rapid evolution in colonizing populations. Here, we leverage nuclear DNA from herbarium specimens of Lygodium japonicum, an invasive fern to 1) identify the putative source(s) of its invasion, 2) test for climate adaptation in its invaded range, and 3) characterize the effects of genetic bottlenecks on adaptive and neutral variation during its establishment. Methods. We use low-coverage genome skimming data from specimens spanning 1905 through 2017 to identify the source region(s) of the L. japonicum invasion of North America. We use a genotype-environment analysis of invaded range samples to identify genomic regions associated with local adaptation to variation in five bioclimatic variables. Finally, we compare heterozygosity between native and invasive individuals and their changes through time in non-coding, coding, and putatively adaptive loci. Key results. We identify mainland Asia as the most likely source region for this invasion. Our genotype-environment analysis found 144 candidate SNPs significantly associated with climatic variation in the invaded range, with precipitation of the driest month associated with the greatest number of SNPs, suggesting rapid genomic adaptation in the invaded range. Finally, we found conflicting trends in individual-level heterozygosity over time when analyzing different types of genetic variation: in non-coding loci, there was a small, yet significant decrease in genetic diversity, but in putatively adaptive loci we did not find evidence of a genetic bottleneck. Conclusions. Natural history collections provide exceptional opportunities to explore evolutionary processes, by capturing genomic sequences across time. Here, herbarium specimens reveal rapid evolution, maintenance of adaptative variation, and accumulation of noncoding diversity in the Lygodium japonicum invasion, highlighting the potential for adaptative variation to fuel the success of invasive species.

evolutionary biology↗

bioRxiv2025

Near chromosome-level genome assembly of Neomusotima conspurcatalis gives insights into the evolution of moth genome architecture and fern-insect interactions

Plant-insect interactions are the foundation of ecosystems globally, yet we are still determining the underlying mechanisms through which these relationships evolve. The co-evolution between insects and their host plants should shape the genomes of both partners, and genes involved in interaction specificity should show unique genomic signatures (e.g., rapid evolution, gene family expansions). Biological control programs are an excellent system for disentangling the genomics and molecular biology of the establishment of an insect and its host plant specificity. Fern-insect relationships are among the most poorly understood, and ferns have long been thought to have few interactions with insects, although recent evidence suggests that these relationships are under-sampled and studied. Here, we present a near-chromosome genome assembly of the crambid moth Neomusotima conspurcatalis, a biological control agent employed in the management of the invasive vining fern Lygodium microphyllum. We use this novel genomic resource to explore the evolution of genome architecture across the Crambidae, revealing highly conserved genome structure across this family of moths. We also examine gene family evolution across the phylogeny and identify expansions in odorant receptor gene families that may be involved in the highly specific interaction of N. conspurcatalis with L. microphyllum. This work highlights the utility of genomics in biological control, and the utility of biological control in informing fundamental understanding of plant-insect interactions. SummaryPlant-insect interactions form the basis of ecological communities and can be highly specific through long lasting co-evolution. Classical biological control provides excellent opportunities to investigate how insect and host genomes are shaped by co-evolutionary processes. We sequenced the genome of Neomusotima conspurcatalis, a biological control moth used to manage the invasive fern Lygodium microphyllum. We analyzed how the structure of the genome has evolved over time relative to other crambid moths and how expansions in gene families involved in odorant reception may be involved in co-evolution with its host. This work provides insight into herbivore interactions in seed-free vascular plants.

evolutionary biology↗