Abstract Hybridization between invasive and native species has raised global concern, given the dramatic increase in species range shifts and pest outbreaks due to anthropogenic dispersal. Nevertheless, secondary contact between sister lineages of local and invasive species provides a natural laboratory to understand the factors that determine introgression and the maintenance or loss of species barriers. Here, we characterize the early evolutionary outcomes following secondary contact between invasive Helicoverpa armigera and native H. zea in Brazil. We carried out whole-genome resequencing of Helicoverpa moths from Brazil in two temporal samples: during the outbreak of H. armigera in 2013 and 2017. There is evidence for a burst of hybridization and widespread introgression from local H. zea into invasive H. armigera coinciding with H. armigera expansion in 2013. However, in H. armigera, the admixture proportion and the length of introgressed blocks were significantly reduced between 2013 and 2017, suggesting selection against admixture. In contrast to the genome-wide pattern, there was striking evidence for adaptive introgression of a single region from the invasive H. armigera into local H. zea, including an insecticide resistance allele that increased in frequency over time. In summary, despite extensive gene flow after secondary contact, the species boundaries are largely maintained except for the single introgressed region containing the insecticide-resistant locus. We document the worst-case scenario for an invasive species, in which there are now two pest species instead of one, and the native species has acquired resistance to pyrethroid insecticides through introgression.

Male butterflies in the hyperdiverse tribe Eumaeini possess an unusually complex and diverse repertoire of secondary sexual characteristics involved in pheromone production and dissemination. Maintaining multiple sexually selected traits is likely to be metabolically costly, potentially resulting in trade-offs in the evolution of male signals. However, a phylogenetic framework to test hypotheses regarding the evolution and maintenance of male sexual traits in Eumaeini has been lacking. Here, we infer a comprehensive, time-calibrated phylogeny from 379 loci for 187 species representing 91% of the 87 described genera. Eumaeini is a monophyletic group that originated in the late Oligocene and underwent rapid radiation in the Neotropics. We examined specimens of 818 of the 1096 described species (75%) and found that secondary sexual traits are present in males of 91% of the surveyed species. Scent pads and scent patches on the wings and brush organs associated with the genitalia were probably present in the common ancestor of Eumaeini and are widespread throughout the tribe. Brush organs and scent pads are negatively correlated across the phylogeny, exhibiting a trade-off in which lineages with brush organs are unlikely to regain scent pads and vice versa . In contrast, scent patches seem to facilitate the evolution of scent pads, although they are readily lost once scent pads have evolved. Our results illustrate the complex interplay between natural and sexual selection in the origin and maintenance of multiple male secondary sexual characteristics and highlight the potential role of sexual selection spurring diversification in this lineage.

Color vision has evolved multiple times in both vertebrates and invertebrates and is largely determined by the number and variation in spectral sensitivities of distinct opsin subclasses. However, because of the difficulty of expressing long-wavelength (LW) invertebrate opsins in vitro, our understanding of the molecular basis of functional shifts in opsin spectral sensitivities has been biased toward research primarily in vertebrates. This has restricted our ability to address whether invertebrate Gq protein-coupled opsins function in a novel or convergent way compared to vertebrate Gt opsins. Here we develop a robust heterologous expression system to purify invertebrate rhodopsins, identify specific amino acid changes responsible for adaptive spectral tuning, and pinpoint how molecular variation in invertebrate opsins underlie wavelength sensitivity shifts that enhance visual perception. By combining functional and optophysiological approaches, we disentangle the relative contributions of lateral filtering pigments from red-shifted LW and blue short-wavelength opsins expressed in distinct photoreceptor cells of individual ommatidia. We use in situ hybridization to visualize six ommatidial classes in the compound eye of a lycaenid butterfly with a four-opsin visual system. We show experimentally that certain key tuning residues underlying green spectral shifts in blue opsin paralogs have evolved repeatedly among short-wavelength opsin lineages. Taken together, our results demonstrate the interplay between regulatory and adaptive evolution at multiple Gq opsin loci, as well as how coordinated spectral shifts in LW and blue opsins can act together to enhance insect spectral sensitivity at blue and red wavelengths for visual performance adaptation.

No abstract

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.

1Colour vision is largely mediated by changes in number, expression, and spectral 2 properties of rhodopsins, but the genetic mechanisms underlying adaptive shifts in 3 spectral sensitivity remain largely unexplored. Using in vivo photochemistry, 4 optophysiology, and in vitro functional assays, we link variation in eye spectral sensitivity 5 at long wavelengths to species-specific absorbance spectra for LW opsins in lycaenid 6butterflies. In addition to loci specifying an ancestral green-absorbing rhodopsin with 7 maximum spectral sensitivity (λ max ) at 520-530 nm in Callophrys sheridanii and 8Celastrina ladon, we find a novel form of red-shifted LW rhodopsin at λ max = 565-570 nm 9in Arhopala japonica and Eumaeus atala. Furthermore, we show that Ca. sheridanii and 10Ce. ladon exhibit a smaller bathochromic shift at BRh2 (480-489 nm), and with the 11 ancestral LW rhodopsin, cannot perceive visible red light beyond 600 nm. In contrast, 12 molecular variation at the LW opsin in A. japonica and E. atala is coordinated with tuning 13 of the blue opsin that also shifts sensitivity to longer wavelengths enabling colour 14 discrimination up to 617 nm. We then use E. atala as a model to examine the interplay 15 between red and blue spectral sensitivity. Owing to blue duplicate expression, the spatial 16 distribution of opsin mRNAs within an ommatidium defines an expanded retinal 17 stochastic mosaic of at least six opsin-based photoreceptor classes. Our mutagenesis in 18 vitro assays with BRh1 (λ max = 435 nm) chimeric blue rhodopsins reveal four main 19 residues contributing to the 65 nm bathochromic shift towards BRh2 (λ max = 500 nm). 20Adaptations in this four-opsin visual system are relevant for discrimination of conspecific 21 reflectance spectra in E. atala. Together, these findings illustrate how functional changes 22 at multiple rhodopsins contribute to the evolution of a broader spectral sensitivity and 23 adaptation in visual performance. 24 Keywords 25 molecular evolution, ecological adaptation, visual system/vision, rhodopsin, spectral sensitivity, in vitro (27, 60, 61, but see 62). Red receptors are intriguingly very common in butterflies 126 compared to other insect groups such as bees or beetles (30), raising the possibility that 127 perception of longer wavelengths plays an important role in the context of foraging (31, 128 46, 63), oviposition (64, 65) and mate recognition (25) for species equipped with them. 129Lycaenids comprise the second largest family of butterflies, representing almost 130 thirty percent of all species, and exhibiting considerable ecological and morphological 131 diversity (66, 67). Pioneering work showed that species of Lycaenidae in the genera 132Lycaena and Polyommatus have expanded spectral sensitivity at long wavelengths, and

Here we show that palm divergence ages track dispersal events linked to recent connection of montane segments across densely faulted topographic gaps in the Northern Andes, and not Andean uplift, highlighting the importance of understanding how mountains form in relation to biogeographic events.

Visual opsins of vertebrates and invertebrates diversified independently and converged to detect ultraviolet to long wavelengths (LW) of green or red light. In both groups, colour vision largely derives from opsin number, expression patterns and changes in amino acids interacting with the chromophore. Functional insights regarding invertebrate opsin evolution have lagged behind those for vertebrates because of the disparity in genomic resources and the lack of robust in vitro systems to characterize spectral sensitivities. Here, we review bioinformatic approaches to identify and model functional variation in opsins as well as recently developed assays to measure spectral phenotypes. In particular, we discuss how transgenic lines, cAMP-spectroscopy and sensitive heterologous expression platforms are starting to decouple genotype–phenotype relationships of LW opsins to complement the classical physiological-behavioural-phylogenetic toolbox of invertebrate visual sensory studies. We illustrate the use of one heterologous method by characterizing novel LW Gq opsins from 10 species, including diurnal and nocturnal Lepidoptera, a terrestrial dragonfly and an aquatic crustacean, expressing them in HEK293T cells, and showing that their maximum absorbance spectra ( λ max ) range from 518 to 611 nm. We discuss the advantages of molecular approaches for arthropods with complications such as restricted availability, lateral filters, specialized photochemistry and/or electrophysiological constraints. This article is part of the theme issue ‘Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods’.