Search

The most emblematic animal traits are often attributed to sexual selection. While this pressure is an important force, elaborated traits that have been driven solely by natural selection are less enumerated. Here, we test an elaborate trait in moths—hindwing tails—that has been studied in an anti-predator context, but that remains unstudied for its role in mating. We gave female Actias luna (Saturniidae) moths a choice between two males of differing hindwing tail treatments. In our primary experiment, males with intact tails garnered more matings than males with tails removed. This difference appears to result from damage incurred by tail removal, however, as demonstrated with additional experiments. We created a tail/no-tail experimental set where we removed tails from both males, then reglued tails to one and applied glue only to the hindwings of the other. We found no significant difference in mating success between these males. To ensure that this result was not due to the glue itself, we offered females two intact males, with glue added to the wings of one. This set also had equal mating success. We therefore do not find evidence that tails play a role in sexual selection. These results, in combination with previous research on bat-moth battles using A. luna, indicate that the non-sexually dimorphic hindwing tail was likely driven by natural selection. We suggest that future research testing multiple selective forces is needed to reveal the prevalence of natural versus sexual selection as the primary force driving trait elaboration in diverse animal taxa.

Circadian rhythms drive many biological patterns, such as activity periods. The temporal partitioning that results can reduce predation, minimize competition, or enable new resource utilization. It can also drive the evolution of sensory systems, such as the highly specialized antennae with which male moths find mates, and the visual specializations with which butterflies escape from birds. However, the mechanisms that underlie such niche-shift adaptations are poorly understood. Many model organisms in circadian biology are too distantly related from one another to elucidate the genetic drivers of diel-niche transitions. To address this, we examined gene expression patterns between two closely related wild silk moth species (Saturniidae), that utilize similar host plants and habitats, but have undergone temporal niche divergence. We found 200-700 differentially expressed genes, including day upregulation in eye development and visual processing genes, and night upregulation of antennal and olfactory brain development genes. We also found clusters of circadian, sensory, and brain development genes co-expressing with diel-activity. Eight genes showed a clear and statistically significant correlation between expression and diel activity in both species, and were involved in vision, olfaction, brain development, neural plasticity, energy utilization, and cellular maintenance. Disconnected (disco), a zinc-finger transcription factor involved in antennal development, circadian activity, and optic lobe brain development in flies, was repeatedly recovered in multiple analyses. Whilediscomutants have circadian arrhythmia, most studies have attributed this to improper clock neuron development, and not directly to adult circadian maintenance. Comparing predicted 3D protein structure across moth (Bombyx mori)and fly (Drosophila melanogaster)genetic models revealeddiscohas likely retained its developmental function with a conserved zinc finger domain, but it has also likely gained novel functional zinc finger domains, highly conserved in moths, but absent inD. melanogaster.These regions had several mutations between nocturnal and diurnal study species that co-occur with higher levels of predicted phosphorylation sites. Together, robust circadian gene expression, functional nocturnal and diurnal mutations with high phosphorylation, structural and sequence conservation, leads us to hypothesize thatdiscomay be a master regulator contributing to the diversification of adult diel activity patterns in adult moths.SignificanceInsects have been longstanding models for understanding circadian and sensory biology. The diversity of diel-activity patterns of insects is tremendous, yet our understanding of the genetic and evolutionary processes leading to this diversity is limited. Light environment is a powerful circadian entrainer that drives diel-niche and sensory evolution. To investigate the evolutionary impact of highly shifted light environments on animals with otherwise similar ecologies, we compared gene expression in closely related day- and night-active wild silkmoths.Genes linked to eye development, neural plasticity and energy cellular maintenance showed expression patterns linked to diel activity. Notably,disco, a gene encoding a zinc finger transcription factor involved in fly (Drosophila melanogaster)optic lobe and antennal development in the pupa, shows robust adult circadian mRNA cycling in moth heads, is highly conserved in moths, and has additional zinc-finger domains with specific nocturnal and diurnal mutations. We hypothesize thatdiscomay contribute to diversification of adult diel-activity patterns in moths.

Rapid identification of organisms is essential across many biological and medical disciplines, from understanding basic ecosystem processes and how organisms respond to environmental change, to disease diagnosis and detection of invasive pests. CRISPR-based diagnostics offers a novel and rapid alternative to other identification methods and can revolutionize our ability to detect organisms with high accuracy. Here we describe a CRISPR-based diagnostic developed with the universal cytochrome-oxidase 1 gene (CO1). The CO1 gene is the most sequenced gene among Animalia, and therefore our approach can be adopted to detect nearly any animal. We tested the approach on three difficult-to-identify moth species (Keiferia lycopersicella, Phthorimaea absoluta, andScrobipalpa atriplicella) that are major invasive pests globally. We designed an assay that combines recombinase polymerase amplification (RPA) with CRISPR for signal generation. Our approach has a much higher sensitivity than other real time-PCR assays and achieved 100% accuracy for identification of all three species, with a detection limit of up to 120 fM forP. absolutaand 400 fM for the other two species. Our approach does not require a lab setting, reduces the risk of cross-contamination, and can be completed in less than one hour. This work serves as a proof of concept that has the potential to revolutionize animal detection and monitoring.

Invasive insects can cause catastrophic damage to ecosystems and cost billions of dollars each year due to management expenses and lost revenue. Rapid detection is an important step to prevent invasive insects from spreading, but improvements in detection capabilities are needed for bulk collections like those from sticky traps. Here we present a bulk DNA extraction method designed for the detection of Phthorimaea absoluta Meyrick (Lepidoptera: Gelechiidae), an invasive moth that can decimate tomato crops. We test the extraction method for insect specimens on sticky traps, subjected to different temperature and humidity conditions, and among mock insect communities left in the field for up to 21 d. We find that the extraction method yielded high success (>92%) in recovering target DNA across field and lab trials, without a decline in recovery after three weeks, across all treatments. These results may have a large impact on tomato growing regions where P. absoluta is in the early stages of invasion or not yet present. The extraction method can also be used to improve detection capabilities for other bulk insect collections, especially those using sticky traps, to the benefit of pest surveys and biodiversity studies.

Arthropod silk is vital to the evolutionary success of hundreds of thousands of species. The primary proteins in silks are often encoded by long, repetitive gene sequences. Until recently, sequencing and assembling these complex gene sequences has proven intractable given their repetitive structure. Here, using high-quality long-read sequencing, we show that there is extensive variation—both in terms of length and repeat motif order—between alleles of silk genes within individual arthropods. Further, this variation exists across two deep, independent origins of silk which diverged more than 500 Mya: the insect clade containing caddisflies and butterflies and spiders. This remarkable convergence in previously overlooked patterns of allelic variation across multiple origins of silk suggests common mechanisms for the generation and maintenance of structural protein-coding genes. Future genomic efforts to connect genotypes to phenotypes should account for such allelic variation.

Understanding the evolutionary origins and factors maintaining alternative life history strategies (ALHS) within species is a major goal of evolutionary research. While alternative alleles causing discrete ALHS are expected to purge or fix over time, one-third of the ~90 species of Colias butterflies are polymorphic for a female-limited ALHS called Alba. Whether Alba arose once, evolved in parallel, or has been exchanged among taxa is currently unknown. Using comparative genome-wide association study (GWAS) and population genomic analyses, we placed the genetic basis of Alba in time-calibrated phylogenomic framework, revealing that Alba evolved once near the base of the genus and has been subsequently maintained via introgression and balancing selection. CRISPR-Cas9 mutagenesis was then used to verify a putative cis-regulatory region of Alba, which we identified using phylogenetic foot printing. We hypothesize that this cis-regulatory region acts as a modular enhancer for the induction of the Alba ALHS, which has likely facilitated its long evolutionary persistence.

We present the first dated molecular phylogeny of the Cerurinae moths (Notodontidae), based on sequence data for 666 loci generated by anchored hybrid enrichment. Monophyly of Cerurinae is corroborated, which includes the following genera: Pararethona Janse, Pseudorethona Janse, Oreocerura Kiriakoff, stat. rev., Cerurella Kiriakoff, Notocerura Kiriakoff, Hampsonita Kiriakoff, Afrocerura Kiriakoff, Cerurina Kiriakoff, Neoharpyia Daniel, Furcula Lamarck, Neocerura Matsumura, Americerura St Laurent and Goldstein, gen. nov., Cerura Schrank, and Kamalia Koçak & Kemal. The type species of the Neotropical genus Tecmessa Burmeister, T. annulipes (Berg), which had been incorrectly assigned to Cerurinae, is recovered in Heterocampinae; and Americeruragen. nov. is proposed to receive 17 unambiguously cerurine species transferred from Tecmessa. Divergence time estimates recover a crown age of Notodontidae roughly coincident with the K-Pg boundary, and a late-Oligocene crown age for Cerurinae. An African origin is inferred for Cerurinae, followed by colonization of the Palearctic, the Americas, Indomalaya, and Australasia during the Miocene. At least three independent colonizations of the Americas are inferred, one in the mid-Miocene associated with ancestral Americeruragen. nov. and two in the Pliocene and Pleistocene within Furcula. We hypothesize that the global spread of Cerurinae was enabled by that of its primary caterpillar foodplants in the Salicaceae. State-dependent diversification analyses suggest that cerurines diversified most rapidly in temperate climates.

Espeland, Marianne, Nakahara, Shinichi, Zacca, Thamara, Barbosa, Eduardo P., Huertas, Blanca, Marín, Mario A., Lamas, Gerardo, Benmesbah, Mohamed, Brévignon, Christian, Casagrande, Mirna M., Fåhraeus, Christer, Grishin, Nick, Kawahara, Akito Y., Mielke, Olaf H. H., Miller, Jacqueline Y., Nakamura, Ichiro, Navas, Vanessa, Patrusky, Brooke, Pyrcz, Tomasz W., Richards, Lindsay, Tan, Denise, Tyler, Stephanie, Viloria, Angel, Warren, Andrew D., Xiao, Lei, Freitas, André V. L., Willmott, Keith R. (2023): Combining target enrichment and Sanger sequencing data to clarify the systematics of the diverse Neotropical butterfly subtribe Euptychiina (Nymphalidae, Satyrinae). Zoological Research 2023: 1-73, DOI: 10.1111/syen.12590

Traits are often caught in a dynamic tension of countervailing evolutionary pressures. Trade-offs can be imposed by predators evolutionarily curtailing the conspicuousness of a sexually selected trait, or acting in opposition to another natural selection pressure, for instance, a different predator with a divergent hunting strategy. Some moon moths (Saturniidae) have long hindwing tails that thwart echolocating bat attacks at night, allowing the moth to escape. These long tails may come at a cost, however, if they make the moth's roosting form more conspicuous to visually foraging predators during the day. To test this potential trade-off, we offered wild-caught Carolina wrens ( Thryothorus ludovicianus ) pastry dough models with real Actias luna wings that were either intact or had tails experimentally removed. We video recorded wrens foraging on models and found that moth models with tails did not experience increased detection and attack by birds. Thus, this elaborate trait, while obvious to human observers, does not seem to come at a cost of increased avian predator attention. The evolution of long hindwing tails, likely driven by echolocating predators at night, does not seem to be limited by opposing diurnal constraints. This study demonstrates the importance of testing presumed trade-offs and provides hypotheses for future testing.

One of the key objectives in biological research is understanding how evolutionary processes have produced Earth’s diversity. A critical step toward revealing these processes is an investigation of evolutionary tradeoffs—that is, the opposing pressures of multiple selective forces. For millennia, nocturnal moths have had to balance successful flight, as they search for mates or host plants, with evading bat predators. However, the potential for evolutionary trade-offs between wing shape and body size are poorly understood. In this study, we used phylogenomics and geometric morphometrics to examine the evolution of wing shape in the wild silkmoth subfamily Arsenurinae (Saturniidae) and evaluate potential evolutionary relationships between body size and wing shape. The phylogeny was inferred based on 782 loci from target capture data of 42 arsenurine species representing all 10 recognized genera. After detecting in our data one of the most vexing problems in phylogenetic inference—a region of a tree that possesses short branches and no “support” for relationships (i.e., a polytomy), we looked for hidden phylogenomic signal (i.e., inspecting differing phylogenetic inferences, alternative support values, quartets, and phylogenetic networks) to better illuminate the most probable generic relationships within the subfamily. We found there are putative evolutionary trade-offs between wing shape, body size, and the interaction of fore- and hindwing (HW) shape. Namely, body size tends to decrease with increasing HW length but increases as forewing (FW) shape becomes more complex. Additionally, the type of HW (i.e., tail or no tail) a lineage possesses has a significant effect on the complexity of FW shape. We outline possible selective forces driving the complex HW shapes that make Arsenurinae, and silkmoths as a whole, so charismatic. [Anchored hybrid enrichment; Arsenurinae; geometric morphometrics; Lepidoptera; phylogenomics; Saturniidae.]

Lepidoptera are a highly diverse group of herbivorous insects; however, some superfamilies have relatively few species. Two alternative hypotheses for drivers of Lepidoptera diversity are shifts in food plant use or shifts from concealed to external feeding as larvae. Many studies address the former hypothesis but with bias toward externally feeding taxa. One of the most striking examples of species disparity between sister lineages in Lepidoptera is between the concealed-feeding sack-bearer moths (Mimallonoidea), which contain about 300 species, and externally feeding Macroheterocera, which have over 74,000 species. We provide the first dated tree of Mimallonidae to understand the diversification dynamics of these moths in order to fill a knowledge gap pertaining to drivers of diversity within an important concealed-feeding clade. We find that Mimallonidae is an ancient Lepidoptera lineage that originated in the Cretaceous ∼105 million years ago and has had a close association with the plant order Myrtales for the past 40 million years. Diversification dynamics are tightly linked with food plant usage in this group. Reliance on Myrtales may have influenced diversification of Mimallonidae because clades that shifted away from the ancestral condition of feeding on Myrtales have the highest speciation rates in the family.

Butterflies are a diverse and charismatic insect group that are thought to have evolved with plants and dispersed throughout the world in response to key geological events. However, these hypotheses have not been extensively tested because a comprehensive phylogenetic framework and datasets for butterfly larval hosts and global distributions are lacking. We sequenced 391 genes from nearly 2,300 butterfly species, sampled from 90 countries and 28 specimen collections, to reconstruct a new phylogenomic tree of butterflies representing 92% of all genera. Our phylogeny has strong support for nearly all nodes and demonstrates that at least 36 butterfly tribes require reclassification. Divergence time analyses imply an origin ~100 million years ago for butterflies and indicate that all but one family were present before the K/Pg extinction event. We aggregated larval host datasets and global distribution records and found that butterflies are likely to have first fed on Fabaceae and originated in what is now the Americas. Soon after the Cretaceous Thermal Maximum, butterflies crossed Beringia and diversified in the Palaeotropics. Our results also reveal that most butterfly species are specialists that feed on only one larval host plant family. However, generalist butterflies that consume two or more plant families usually feed on closely related plants., Funding came from the US National Science Foundation (NSF) GoLife ‘ButterflyNet’ collaborative grant (DEB-1541500, 1541557, 1541560) to A.Y.K., R.P.G., D.J.L. and N.E.P. Specimen collection and preservation was funded by NSF DBI-1349345, 1601369, DEB-1557007 and IOS-1920895 (A.Y.K.), NSF DEB-1120380 (D.J.L.), grants 9285-13 and WW-227R-17 from the National Geographic Society (D.J.L.), NSF DBI-1256742 (A.Y.K. and K.R.W.), NSF DEB-0639861 (K.R.W.) and NSF SES-0750480, DEB-0447244 and DEB-9615760 (N.E.P.). M.E. was supported by the Research Council of Norway (no. 204308) and the Hintelmann Scientific Award for Zoological Systematics. F.L.C. was supported by the European Research Council under the European Union’s Horizon 2020 research and innovation programme (project GAIA, no. 851188). M.P.B. was supported by the Swedish Research Council (IPG no. 2020‐06422). R.V. was supported by the Spanish Ministry of Science and Innovation grant PID2019-107078GB-I00/AEI/10.13039/501100011033. G.T. was supported by the Spanish Ministry of Science and Innovation (grants PID2020-117739GA-I00/AEI/10.13039/501100011033 and RYC2018-025335-I). V.L. was supported by the Russian Science Foundation (grant 19-14-00202) and by the Ministry of Science and Higher Education of the Russian Federation (grant 075-15-2021-1069). M.Y. was supported by MEXT KAKENHI no. 19916010 and JSPS KAKENHI grants 13010131, 23570111, 26440207, 17K07528 and 21H02215. A.B.B.M., H.P.R. and N.O.M. were supported by CNPQ grants proc 563332/2010-7 and 304273/2014-7., Main Results and discussion Methods Data availability Code availability References Acknowledgements Author information Ethics declarations Peer review Additional information Supplementary information Rights and permissions About this article

Arthropod silk is vital to the evolutionary success of hundreds of thousands of species. The primary proteins in silks are often encoded by long, repetitive gene sequences. Until recently, sequencing and assembling these complex gene sequences has proven intractable given their repetitive structure. Here, using high-quality long-read sequencing, we show that there is extensive variation—both in terms of length and repeat motif order—between alleles of silk genes within individual arthropods. Further, this variation exists across two deep, independent origins of silk which diverged more than 500 million years ago—(1) the insect clade containing caddisflies and butterflies and (2) spiders. This remarkable convergence in previously overlooked patterns of allelic variation across multiple origins of silk suggests mechanisms for the generation and maintenance of structural protein-coding genes. Future genomic efforts to connect genotypes to phenotypes should account for such allelic variation.

Lepidopteran silks are produced during the larval stage and are used for mobility and protection from predators, parasitoids, and pathogens. Our knowledge of silk structure and production in Lepidoptera is based largely on the biology of the domestic silk moth (Bombyx mori), but recent comparative evidence suggests that silk production and structure vary widely across moth taxa. Some species like the Indian meal moth (Plodia interpunctella) are becoming important biological models to study silk for its potential application to materials science and medicine, but many aspects of silk production in this species remain unknown. Here we characterize the silk ofP. interpunctellaby measuring the width of wandering and pupal silk strands and find that pupal silk is significantly thicker than the latter. We then report individual variation in pupal silk production in our lab-reared colony with a very small number of individuals forgoing pupal silk (< 4%) and find that overcrowding had no effect on this, whereas exposure to elevated temperatures reduced rates of pupal silk production.

Temperature is thought to be a key variable explaining global patterns of species richness. However, to investigate this relationship carefully, it is necessary to study clades with broad geographic ranges that are comprised of species inhabiting diverse biomes with well- characterized species ranges. In the present study, we investigate the link between temperature and diversification in the butterfly family Pieridae (sulfurs and whites) by combining Next Generation sequences and published molecular data with fine-grained distribution information. After building the most comprehensive phylogeny of the group, with almost 600 species and all higher taxa (subfamilies, tribes and subtribes), we found strong support for the following relationships within the family: Dismorphiinae + (Coliadinae + (Pseudopontiinae + Pierinae)). With a curated distribution dataset of over 800,000 occurrences, we conducted multiple comparative phylogenetic analyses that provided strong evidence that species in environments with more stable daily temperatures or with cooler maximum temperatures in the warm seasons have higher diversification rates. We also found a positive correlation between speciation and extinction with paleotemperature: as global temperature decreased through geological time, so did diversification rates. Although many studies demonstrate higher diversity in the tropics, we have been able to identify specific climate variables associated with changes in diversification, while also inferring the most robust and well sampled phylogenomic framework for Pieridae to date.

Butterflies and moths (Lepidoptera) are one of the most studied, diverse, and widespread animal groups, making them an ideal model for climate change research. They are a particularly informative model for studying the effects of climate change on species ecology because they are ectotherms that thermoregulate with a suite of physiological, behavioural, and phenotypic traits. While some species have been negatively impacted by climatic disturbances, others have prospered, largely in accordance with their diversity in life‐history traits. Here we take advantage of a large repertoire of studies on butterflies and moths to provide a review of the many ways in which climate change is impacting insects, animals, and ecosystems. By studying these climate‐based impacts on ecological processes of Lepidoptera, we propose appropriate strategies for species conservation and habitat management broadly across animals.

Warning signals are well known in the visual system, but rare in other modalities. Some moths produce ultrasonic sounds to warn bats of noxious taste or to mimic unpalatable models. Here, we report results from a long-term study across the globe, assaying moth response to playback of bat echolocation. We tested 252 genera, spanning most families of large-bodied moths, and document anti-bat ultrasound production in 52 genera, with eight subfamily origins described. Based on acoustic analysis of ultrasonic emissions and palatability experiments with bats, it seems that acoustic warning and mimicry are the raison d'être for sound production in most moths. However, some moths use high-duty-cycle ultrasound capable of jamming bat sonar. In fact, we find preliminary evidence of independent origins of sonar jamming in at least six subfamilies. Palatability data indicate that jamming and warning are not mutually exclusive strategies. To explore the possible organization of anti-bat warning sounds into acoustic mimicry rings, we intensively studied a community of moths in Ecuador and, using machine-learning approaches, found five distinct acoustic clusters. While these data represent an early understanding of acoustic aposematism and mimicry across this megadiverse insect order, it is likely that ultrasonically signaling moths comprise one of the largest mimicry complexes on earth.

Butterflies are a diverse and charismatic insect group that are thought to have diversified via coevolution with plants and in response to dispersals following key geological events. These hypotheses have been poorly tested at the macroevolutionary scale because a comprehensive phylogenetic framework and datasets on global distributions and larval hosts of butterflies are lacking. We sequenced 391 genes from nearly 2,000 butterfly species to construct a new, phylogenomic tree of butterflies representing 92% of all genera and aggregated global distribution records and larval host datasets. We found that butterflies likely originated in what is now the Americas, ∼100 Ma, shortly before the Cretaceous Thermal Maximum, then crossed Beringia and diversified in the Paleotropics. The ancestor of modern butterflies likely fed on Fabaceae, and most extant families were present before the K/Pg extinction. The majority of butterfly dispersals occurred from the tropics (especially the Neotropics) to temperate zones, largely supporting a “cradle” pattern of diversification. Surprisingly, host breadth changes and shifts to novel host plants had only modest impacts.