A common explanation for bats being a conspicuous source of zoonotic viruses is their purported ability to coexist with viruses without suffering overt disease. Widespread acceptance of the idea that bats have unusual antiviral traits has catalyzed the discovery of unique features of bat immune systems which may have translational value as broad-spectrum antivirals, particularly if they evolved as a byproduct of bats' unique life history rather than through conventional co-evolutionary processes. Surprisingly, whether bats compared to other host groups suffer less disease from co-evolved viruses or from viruses generally has not been formally assessed. Here, synthesizing 86 years of experimental infections, involving 54 viruses, 85 host species, and over 5,600 animals, we document disease in bats following inoculation by taxonomically diverse viruses, including ones that are relatively benign in humans. The occurrence of overt disease, the likelihood of mortality, and the severity of disease in bats were indistinguishable from those experienced by rodents, another group associated with many zoonotic viruses. These patterns were consistent when considering only bat-associated viruses inoculated into bats and rodent-associated viruses inoculated into rodents and among inoculations which lacked shared co-evolutionary history. Instead, disease outcomes following infection were shaped by experimental design, viral host range, and evolutionary context. Unexceptional disease in bats from novel or co-evolved infections suggests that order-level host life history traits such as flight have inconsistent consequences for antiviral immunity and highlights the need to evaluate the functional properties of putatively unique features of bat immunity in vivo. While these results do not exclude the possibility of developing broader-acting or more potent antivirals from bat immune systems or diminish the potential value of mechanistic insights into bat immunity, they suggest that bat immune systems were shaped by conventional co-evolutionary processes rather than through unique circumstances that endow exceptional antiviral defenses.

The study of evolution in organisms with high mutation rates requires detailed data on the genomic composition of the population. Here we report on an innovative use of high-throughput sequencing technology combined with rapid experimental evolution that allowed us to follow the genetic diversification of four independent bacteriophage populations for 412 generations in extraordinary detail. One of our goals was to assess phylodynamic methods that use genetic information to infer key parameters of the population history. Because phylodynamic methods assume neutral evolution, we did not actively impose any selection pressures in our evolution experiment (in addition to those inherent in the bacterial cell environment). Tracing over 80'000 bacteriophage genomes, representing 884 distinct genotypes, we find that the patterns of viral diversification result in largely non-congruent genotype distributions, but also document multiple instances of parallel evolution. Unlike previous observations of parallelism in viral evolution, we do not just see the parallel evolution of mutations at single sites, but on the level of full-length genomes. Computer simulations that recapitulate our experiments in great detail show that this degree of parallelism is inconsistent with neutral evolution. We further show that the observed extent of parallel evolution biases phylodynamic analysis of migration rates, and wrongly estimates significant migration between the independent evolution lines. Our approach is applicable to many other viruses and paves the way to advanced population genetic investigations that aim to shed light on phenomena that relate to genetic linkage across the genome.

Goal-directed behavior requires sensory information to be transformed into motor commands, yet the precise temporal structure of communication between sensory and motor cortices during this process remains poorly understood. By simultaneously recording spiking activity from primary somatosensory cortex (S1) and secondary motor cortex (M2) in mice performing a tactile delayed go/no-go task, we identified a brief, stimulus-triggered communication window that predicted behavioral success. Time-shifted canonical correlation analysis revealed a sharp, feedforward surge in S1 → M2 coupling peaking at a short latency, as expected for a potentially direct transmission pathway. This transient interaction conveyed stimulus-selective information such that the S1 → M2 communication subspace aligned with stimulus-coding axes in both regions. In contrast, M2 → S1 feedback interactions were weaker and delayed. Brief optogenetic suppression of S1 reduced both M2 stimulus selectivity and behavioral discriminability, consistent with a functional role of the transient S1 → M2 coupling. These findings demonstrate that sensorimotor transformation is supported not by sustained linear coupling along the stimulus- or choice- axis, but by a short-lived and highly selective feedforward communication channel that rapidly transmits reliable sensory representations into motor-planning circuits.

Molecular profiling studies have mapped vascular alterations in Alzheimer's disease, but have not proven a role for them in pathology. Longitudinal studies are needed to link molecular and structural changes to vascular mechanics, hemodynamics, and tissue perfusion.

Bat sarbecoviruses differ in the range of mammalian ACE2 receptors they can use, complicating predictions of spillover risk. Two new studies in PLOS Biology link receptor breadth with antigenic relatedness and reveal conserved spike epitopes targetable by antibodies.

[This corrects the article DOI: 10.1371/journal.pbio.3002841.].

Sexual selection is a central force in evolutionary biology that has been shown to shape phenotypes and population dynamics in animals. While this selective force is increasingly recognized in flowering plants, theory predicts that anisogamy generates sex differences in the fitness benefits of acquiring additional mates-a pattern well supported in animals but with limited tests in plants. Plant studies rely solely on genetic parentage analyses to estimate mate numbers, thereby conflating performance in accessing mates with success in gamete fertilization. Pollinators add an ecological layer, as their behavior and abundance can influence competition for access to mates and their gametes. Here, we disentangle consecutive episodes of sexual selection in the hermaphroditic plant Brassica rapa by combining direct observations of Bombus terrestris movements with genetic paternity analyses in experimental populations, thus providing independent estimates of the observational number of mates acquired and realized fertilization success. Our approach identifies pollen competition for ovules as the primary arena for sexual selection in B. rapa. Competition for access to mates constitutes a secondary force and was found to be stronger in the male compared to the female sex function, as predicted by classic theory. Experimentally reduced pollinator abundance modulated the balance between pre- and post-pollination sexual selection, increasing the opportunity for selection on mate acquisition. Ignoring pollinator movements led to biased estimates of pre-pollination sexual selection. Our findings demonstrate that sexual selection in plants unfolds across multiple, sequential episodes shaped by ecological context.

Male mosquitoes locate females through strong and innate attraction to female flight sounds, the basis of mating in the world's deadliest animal. In contrast, females do not show any sound attraction behaviors. Despite being documented for almost a century, the molecular underpinnings of these behavioral dimorphisms remain unknown. Here, we found that by disrupting the male-specific isoform of fruitless (referred to as fruM) in Aedes aegypti, fruM mutant males show complete abolition of sound attraction behaviors, resulting in failure of mutant males to locate females for mating. We identified strong fruitless expression in control male ears, with the loss of FruM severely disrupting mutant male ability to amplify female flight sounds. fruM mutant male ears also propagate frequency-specific, sound-evoked electrical signals at about one-sixth the magnitude of control males, significantly reducing the amount of auditory information relayed to the brain. fruitless thus plays a significant role in determining proper male peripheral hearing function underlying mating. Transcriptomic analyses of mosquito ears identified essential hearing genes under the transcriptional influence of FruM via direct or indirect actions, thus shaping male-specific hearing cellular machineries that support male attraction to female flight sounds. Our work demonstrates that FruM commands male-specific hearing behaviors involved in mating by directly controlling the earliest stages of auditory organ performance, sound amplification and acoustic signal detection. Our findings show that FruM is essential for male-specific reproductive behaviors in mosquitoes.

Some bacteriophages encode lysis proteins that inhibit essential bacterial processes, and elucidating their mechanisms is valuable for developing antibacterial strategies against drug-resistant pathogens. We determined the cryo-EM structure of the complex between the essential Escherichia coli lipid II flippase MurJ and the phage lysis protein SglPP7. Structural, mutational, and molecular dynamics (MD) simulation analyses revealed that SglPP7 binds along the intramembrane cleft of MurJ and inserts its C-terminal tail into the internal cavity, stabilizing MurJ in an outward-facing conformation. Structural comparison with LysM (SglM) and SglCJ3 showed that these sequence-divergent Sgl proteins stabilize MurJ in the outward-facing conformation through distinct binding modes, consistent with the possibility of convergent evolution toward MurJ inhibition.

Forecasts of whether marine species can evolve fast enough to survive climate change rely largely on single-stage tolerance assays, tacitly assuming that tolerance measured at one developmental stage reflects adaptive capacity across the organism's life cycle. We test this assumption in a common marine bivalve (Mercenaria mercenaria) and find that it fails in sign, not degree: larval and post-metamorphic tolerance to end-century ocean acidification are strongly negatively correlated (r = -0.53, 95% CI [-0.69, -0.33]) across family-level, pedigree-conditioned and animal model estimates, with pervasive rank reversals among the top performers of each stage. A multivariate analysis of the among-family covariance matrix G shows why: under acidification, 57% of the among-family variance collapses onto a single dominant axis that loads positively on every larval trait and negatively on every post-metamorphic trait, whereas under ambient conditions the same families show no cross-stage covariance at all. Acidification therefore does not merely depress performance-it reorganizes the genetic architecture into a cross-stage conflict. Under ramping RCP 8.5 forcing this conflict geometry dictates the direction-not merely the magnitude-of adaptation: only balanced multi-stage selection preserves family diversity, whereas single-stage selection systematically erodes the opposite axis. In complex life cycles, resilience is a geometric property of ontogeny that forecasts cannot compress into a single-stage without inverting the sign of the answer.

The central problem when delivering drugs to the brain is no longer crossing the blood-brain barrier, but delivering therapeutics to the right cells, in the right regions to target neurodegeneration, within a dynamically changing neurovascular unit.

Past climate change has repeatedly reshaped Earth's biomes, yet how their expansion and contraction influence biodiversity patterns through time remains unclear. Competing hypotheses propose that either historical biome area has a strong influence on diversity, or that biodiversity responds rapidly to environmental change, such that present-day biome area and energy are sufficient to explain diversity patterns. Progress in testing these ideas has been limited by sparse and inconsistent proxy data and the coarse resolution of existing paleoclimate models. Here, we reconstructed global biome histories for the Cenozoic (66-0 Ma) by downscaling five different paleoclimate simulations. Estimates of change in biome area through time were generally consistent among alternative climate models and with the empirical proxy record. Accounting for variation among models, we found that present-day area and energy were consistently better predictors of vertebrate diversity than historical measures. These findings suggest biodiversity tracks the ecological limits set by shifting biomes, leaving sparse legacy of past dynamics. Our results highlight the importance of integrating multiple paleoclimate reconstructions when assessing the historical drivers of biodiversity.

Why do hosts and parasites vary so much? A new study in PLOS Biology reveals that infection outcomes strongly depend upon interacting effects of host and parasite genotypes, offering an evolutionary explanation for profound and persistent variability.

How does the human brain represent the meaning of abstract symbols? Some theories postulate the existence of semantic spaces where concepts occupy positions that reflect their conceptual relationships. In the number domain, psychological evidence suggests that integers are represented along a mental number line which, with education, integrates higher-level number concepts such as fractions. To test this hypothesis, we recorded whole-brain 7T fMRI responses to integer and fraction symbols during an active magnitude comparison task designed to engage magnitude processing. Consistent with predictions, we found both behavioral and neural numerical distance effects. Activation vectors in intraparietal, inferior temporal, prefrontal, hippocampal, and parahippocampal cortices formed a two-dimensional semantic space organized by numerical magnitude and domain (fractions versus integers). Gaussian fits revealed a topographic map of numerical preferences in the anterior inferior parietal cortex, common to both domains. Our results suggest that, when educated adults engage in an explicit magnitude comparison task, their brain can construct an ordered representation that integrates fractions and integers, with a topographic organization in the anterior IPS/IPL.

Host-parasite coevolution is expected to generate strong selection for resistance and infectivity that has the potential to erode genetic variation. Despite this, natural populations often retain extensive genetic variation in these traits. Genotype-by-genotype interactions on fitness can generate negative frequency-dependent selection, which helps maintain this variation by preventing any host or pathogen genotype from retaining a permanent advantage. Because these interactions place genetic variance in the interaction term rather than in additive differences among hosts or pathogens, that variance is masked from directional selection and can remain 'cryptic'. Here we combine coevolutionary modelling with large‑scale experimental infection assays to quantify how host-pathogen interactions structure fitness variance in a vertically transmitted virus system, Drosophila melanogaster and sigma virus. Simulations show that coevolution typically erodes additive genetic variance in host and pathogen fitness, concentrating variance in host-virus interaction terms. Consistent with these predictions, experiments spanning 90 host-virus genotype combinations reveal that transmission, viral load, and virulence are overwhelmingly governed by host-virus genetic interactions rather than host or virus main effects. As a result, neither host resistance alleles nor viral genotypes confer consistently higher fitness across genetic backgrounds. Interactions tend to be sex‑specific, further limiting heritable fitness variation. Our results demonstrate that coevolution can substantially mask heritable genetic variation from directional selection by rendering fitness context-dependent. This extensive cryptic genetic variation may be revealed either when ecological or evolutionary conditions shift, or when the process of coevolution itself alters the direction of selection. This demonstrates the need to account for genotype-specific interactions when forecasting evolutionary responses.