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Abstract Leafhoppers comprise over 20,000 plant‐sap feeding species, many of which are important agricultural pests. Most species rely on two ancestral bacterial symbionts,SulciaandNasuia, for essential nutrition lacking in their phloem and xylem plant sap diets. To understand how pest leafhopper genomes evolve and are shaped by microbial symbioses, we completed a chromosomal‐level assembly of the aster leafhopper's genome (ALF;Macrosteles quadrilineatus). We compared ALF's genome to three other pest leafhoppers,Nephotettix cincticeps,Homalodisca vitripennis, andEmpoasca onukii, which have distinct ecologies and symbiotic relationships. Despite diverging ~155 million years ago, leafhoppers have high levels of chromosomal synteny and gene family conservation. Conserved genes include those involved in plant chemical detoxification, resistance to various insecticides, and defence against environmental stress. Positive selection acting upon these genes further points to ongoing adaptive evolution in response to agricultural environments. In relation to leafhoppers' general dependence on symbionts, species that retain the ancestral symbiont,Sulcia, displayed gene enrichment of metabolic processes in their genomes. Leafhoppers with bothSulciaand its ancient partner,Nasuia, showed genomic enrichment in genes related to microbial population regulation and immune responses. Finally, horizontally transferred genes (HTGs) associated with symbiont support ofSulciaandNasuiaare only observed in leafhoppers that maintain symbionts. In contrast, HTGs involved in non‐symbiotic functions are conserved across all species. The high‐quality ALF genome provides deep insights into how host ecology and symbioses shape genome evolution and a wealth of genetic resources for pest control targets. 

Abstract A collection of quaternary, high-MgO (≤13.4 wt%) basanite and minette cinder and lava cones, with an enhanced arc geochemical signature, are located along the northern margin of the N–S Colima rift in western Mexico. The Colima rift overlies the lithospheric suture between the Jalisco block and Guerrero terrane, as well as the tear between the Rivera and Cocos subducting oceanic plates. From the literature, volatile analyses of olivine-hosted melt inclusions in the Colima cone samples document notably high concentrations of dissolved H2O in the melt (≤ 7.0 wt%) as well as degassing-induced phenocryst growth over a range of depths ≤25 km. In this study, it is shown that the high-MgO character of the Colima suite reflects liquid compositions, consistent with evidence for their rapid transit to the surface, without stalling in a crustal magma chamber. The most Mg-rich olivine analyzed in each sample matches the equilibrium composition at the liquidus based on olivine-melt Mn–Mg and Fe2+–Mg exchange coefficients. Application of both a Mg- and Ni-based olivine-melt thermometer, calibrated on the same experimental data set, to the Colima cone suite provides the temperature and dissolved H2O content at the liquidus. Because the Ni thermometer is insensitive to dissolved H2O in the melt, it gives the actual temperature at the onset of olivine phenocryst growth. For the nine Colima samples that range from 13.4–9.2 wt% MgO, resulting temperatures range from 1221°C to 1056°C (± 6–11°C). In contrast, the Mg thermometer is sensitive to dissolved H2O in the melt, and its application (without a correction of H2O) gives the temperature of olivine crystallization under anhydrous conditions. When the Mg- and Ni-based temperatures are paired, the depression of the liquidus (∆T = TMg–TNi) due to dissolved H2O can be obtained. For the high-MgO (>9 wt%) Colima samples, ∆T values range from 188°C to 109°C. Corrections for the effect of pressure (i.e. evidence that phenocryst growth began at ~700 MPa), increase ∆T by ~21°C. An updated model calibration (on experiments from the literature) that relates ∆T with dissolved H2O in the melt shows that the best fit (R2 = 0.95) is linear, wt% H2O = 0.047*∆T, with a standard error of ±0.5 wt%. Although the experimental data set spans a wide range of melt composition (e.g. 47–58 wt% SiO2, 4.4–10.2 wt% MgO, 1.3–4.9 wt% Na2O, 0.1–5.0 wt% K2O, 0.3–5.3 wt% H2O), no dependence on anhydrous melt composition is resolved. Application of this updated model to the Colima suite gives H2O contents of 5.1–8.8 wt% H2O, consistent with those analyzed in olivine-hosted MIs from the literature. When the thermometry and hygrometry results for the Colima cone suite are compared to those for the adjacent calc–alkaline basalts from the Tancítaro Volcanic Field (TVF) in Michoacán, two distinct linear trends in a plot of wt% H2O vs. temperature are found, indicative of different mantle sources. It is proposed that the high-MgO (>11 wt%) Colima cone melts were derived from a phlogopite-bearing harzburgitic mantle at the base of the Jalisco block lithosphere, whereas both TVF and Colima melts with ≤10 wt% MgO were derived from the asthenosphere (i.e. arc mantle wedge). In both mantle sources, slab-derived fluids were an important source of H2O. 

Abstract Planthoppers in the family Cixiidae (Hemiptera: Auchenorrhyncha: Fulgoromorpha) harbor a diverse set of obligate bacterial endosymbionts that provision essential amino acids and vitamins that are missing from their plant-sap diet. “Candidatus Sulcia muelleri” and “Ca. Vidania fulgoroidea” have been associated with cixiid planthoppers since their origin within the Auchenorrhyncha, whereas “Ca. Purcelliella pentastirinorum” is a more recent endosymbiotic acquisition. Hawaiian cixiid planthoppers occupy diverse habitats including lava tube caves and shrubby surface landscapes, which offer different nutritional resources and environmental constraints. Genomic studies have focused on understanding the nutritional provisioning roles of cixiid endosymbionts more broadly, yet it is still unclear how selection pressures on endosymbiont genes might differ between cixiid host species inhabiting such diverse landscapes, or how variation in selection might impact symbiont evolution. In this study, we sequenced the genomes of Sulcia, Vidania, and Purcelliella isolated from both surface and cave-adapted planthopper hosts from the genus Oliarus. We found that nutritional biosynthesis genes were conserved in Sulcia and Vidania genomes in inter- and intra-host species comparisons. In contrast, Purcelliella genomes retain different essential nutritional biosynthesis genes between surface- and cave-adapted planthopper species. Finally, we see the variation in selection pressures on symbiont genes both within and between host species, suggesting that strong coevolution between host and endosymbiont is associated with different patterns of molecular evolution on a fine scale that may be associated with the host diet. 

Odor stimuli consist of thousands of possible molecules, each molecule with many different properties, each property a dimension of the stimulus. Processing these high dimensional stimuli would appear to require many stages in the brain to reach odor perception, yet, in mammals, after the sensory receptors this is accomplished through only two regions, the olfactory bulb and olfactory cortex. We take a first step toward a fundamental understanding by identifying the sequence of local operations carried out by microcircuits in the pathway. Parallel research provided strong evidence that processed odor information is spatial representations of odor molecules that constitute odor images in the olfactory bulb and odor objects in olfactory cortex. Paleontology provides a unique advantage with evolutionary insights providing evidence that the basic architecture of the olfactory pathway almost from the start ∼330 million years ago (mya) has included an overwhelming input from olfactory sensory neurons combined with a large olfactory bulb and olfactory cortex to process that input, driven by olfactory receptor gene duplications. We identify a sequence of over 20 microcircuits that are involved, and expand on results of research on several microcircuits that give the best insights thus far into the nature of the high dimensional processing. 

Coevolution—reciprocal evolutionary change between interacting lineages (Thompson, 1994; see Glossary)—is thought to have played a profound role in the evolution of Life on Earth. From similar patterns across the wings of unrelated lineages of butterflies (Hoyal Cuthill and Charleston, 2015), egg mimicry of “cheating” brood parasites (Davies, 2010), to the role of animal pollinators in driving the diversification of flowering plants (Kay and Sargent, 2009), to the ubiquity of sexual reproduction and sexual conflicts (Hamilton, 2002; Arnqvist and Rowe, 2005; King et al., 2009), the formation of the eukaryotic cell (Martin et al., 2015; Imachi et al., 2020), and even the origin of living organisms themselves (Mizuuchi and Ichihashi, 2018), evolutionary changes among interacting lineages have played profound and important roles in the history of Life. This Grand Challenges inaugural contribution encompasses eclectic opinions of the editorial board as to what are the next frontiers of coevolution research in the 21st century. Coevolutionary biology is a field that has garnered a lot of attention in recent years, in part as a result of technical advances in nucleotide sequencing and bioinformatics in the burgeoning field of host–microbial interactions. Many seminal studies of coevolution examined reciprocal evolutionary change between two or a few interacting macroscopic species that imposed selective pressures on one another (e.g., insect or bird pollinators and their flowering host plants). Understanding the contexts under which coevolution occurs, as opposed to scenarios in which each partner adapts independently to a particular environment (Darwin, 1862; Stiles, 1978) is important to elucidate coevolutionary processes. A whole spectrum of organismal interactions has been examined under the lens of coevolution, providing additional context, and nuance to ecological strategies traditionally categorized as ranging from beneficial to detrimental for participating species (Figure 1). In particular, a coevolutionary perspective has revealed that even “mutualisms” are not always fully beneficial or cooperative for the partners involved. Instead, the tendency to “cheat” permeates across symbiotic partnerships (Perez-Lamarque et al., 2020). Conversely, recent evidence suggests that non-lethal predation by co-evolved predators, which has traditionally been assumed to be entirely antagonistic, may provide sessile prey with some indirect benefit through enhanced opportunities to acquire beneficial symbiotic microorganisms (Grupstra et al., 2021). Herein, we discuss some of the recent areas of active research in coevolution, restricting our focus to coevolution between interacting species. 

Abstract Despite the f₀(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark ($${{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}$) meson, a tetraquark ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}q\overline{q}$) exotic state, a kaon-antikaon ($${{\rm{K}}}\overline{{{\rm{K}}}}$$ $K\overline{K}$) molecule, or a quark-antiquark-gluon ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{g}}}$$ $q\overline{q}g$) hybrid. This paper reports strong evidence that the f₀(980) state is an ordinary$${{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}$meson, inferred from the scaling of elliptic anisotropies (v₂) with the number of constituent quarks (n_q), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f₀(980) state is reconstructed via its dominant decay channel f₀(980) →π⁺π⁻, in proton-lead collisions recorded by the CMS experiment at the LHC, and itsv₂is measured as a function of transverse momentum (p_T). It is found that then_q= 2 ($${{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}$state) hypothesis is favored overn_q= 4 ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}q\overline{q}$or$${{\rm{K}}}\overline{{{\rm{K}}}}$$ $K\overline{K}$states) by 7.7, 6.3, or 3.1 standard deviations in thep_T< 10, 8, or 6 GeV/cranges, respectively, and overn_q= 3 ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{g}}}$$ $q\overline{q}g$hybrid state) by 3.5 standard deviations in thep_T< 8 GeV/crange. This result represents the first determination of the quark content of the f₀(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates.