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bioRxiv2026

Urban green space exposure reduces subjective stress and physiological arousal

Stress is a major risk factor for mental disorders, and urban living is a key environmental contributor. Nature exposure may promote stress recovery and mental health, but how physiological arousal and subjective stress change across green versus gray space during naturalistic urban mobility is poorly understood. This preregistered study (https://doi.org/10.17605/OSF.IO/HF4RW) employed geolocation-based ambulatory assessment to examine psychophysiological arousal and subjective stress during transitions between urban green and gray environments. Thirty-six healthy urban residents completed a counterbalanced circular walking route in Cologne, Germany, with continuous GPS, cardiovascular, and electrodermal recording alongside ecological momentary assessment of subjective stress, affect, and exertion. Green compared to gray spaces were associated with lower subjective stress and higher affective well-being, with cardiac indices reflecting reduced autonomic arousal during green space exposure. Autonomic changes surrounding environmental transitions persisted beyond the immediate transition window, suggesting that physiological benefits of green space exposure extend into subsequent gray environments. These findings underscore the public health potential of urban green infrastructure for preventing stress-related mental health conditions.

physiology↗

bioRxiv2026

The ribosomal DNA landscape of mammalian muscle during acute and chronic physiological stress

Ribosomal DNA (rDNA) is a highly repetitive and complex locus within the mammalian genome that exhibits substantial inter-individual variation in number of rDNA copies and epigenetic regulation. Nonetheless, our understanding of rDNA biology in skeletal muscle during periods of physiological stress is limited. Using publicly available whole genome and reduced representative bisulfite sequencing data sets, we identify a concurrent reduction in both the number of rDNA copies and the methylation profile of the rDNA in aged vs young mice, supported by large effect sizes and permutation testing, with significant reductions in methylation of the 18S coding unit in aged, compared to young controls (p = 0.024). We found a strong positive correlation between rDNA copy number and 18S methylation across both young and aged mice (p = 0.004; Spearman rho = 0.842). After analysing publicly available muscle (skeletal and cardiac) data sets following acute insult (endurance exercise, cancer cachexia, spinal cord injury), we do not observe a similarly coordinated epi-genetic modification in rDNA biology but uncover tissue and sex-specific differences in rDNA copy number or methylation status, in isolation. These findings suggest ageing as a unique physiological insult in which coordinated epi-genomic remodelling of the rDNA region appears, representing a previously underappreciated feature of the muscle ageing trajectory.

physiology↗

bioRxiv2026

Distinct patterns of skeletal muscle wasting and mitochondrial changes following hypoxia and inflammation: associations with physiological phenotype

Skeletal muscle demonstrates a high degree of plasticity that may enable mitochondrial and protein turnover adaptations to environmental stressors such as hypoxia and inflammation. However, the effects of these stressors on skeletal muscle mitochondrial function and proteostatic pathways remain incompletely understood and may depend on muscle phenotype. Given the potential heterogeneity in skeletal muscle responses to these stressors, this study investigated their independent and combined effects on mitochondrial function and protein turnover pathways in oxidative soleus and glycolytic plantaris and assessed the consistency of these responses by comparison with a previous cohort. Adult male Wistar rats were exposed for four weeks to normobaric hypoxia and/or lipopolysaccharide-induced pulmonary inflammation. Mitochondrial respiration, enzymatic activities, markers of mitochondrial function and protein turnover and spontaneous locomotor activity (SLA) were assessed. Pulmonary inflammation predominantly affected soleus, triggering atrophy alongside impaired CI-dependent mitochondrial function, without changes in mitochondrial density. In contrast, plantaris exhibited only atrophy with no mitochondrial alterations in response to inflammation. Hypoxia induced atrophy selectively in plantaris. Notably, the changes following exposure to inflammation and/or hypoxia occurred independently of SLA alterations while the combination of these two stressors did not produce additive effects for most parameters. Comparison with our previous cohort revealed divergent responses that may have been influenced by differences in several physiological characteristics between the two cohorts. These findings demonstrate that hypoxia and pulmonary inflammation induce muscle-specific adaptations and suggest that physiological heterogeneity may contribute to variability in skeletal muscle vulnerability to chronic stress.

physiology↗

bioRxiv2016

Physiological reason for ceasing growth of unfertilized eggs produced by unmated queens in the subterranean termite Reticulitermes chinensis

In Reticulitermes chinensis, a close relative of R. speratus with asexual queen succession, unfertilized eggs can be produced but are not incubated. To explain this phenomenon, we analysed the physiological differences between unfertilized eggs/unmated queens and fertilized eggs/mated queens. Fertilized eggs consumed significantly larger quantities of five amino acids (Cys, Met, Ile, Leu and Tyr), Ca, protein and cholesterol during incubation. The higher levels of four trace elements (Na, K, Zn and Fe) in fertilized eggs and their lower levels in mated queens indicated that mated queens might transfer these trace elements to fertilized eggs to complete incubation. The higher levels of Mn, triglycerides and serotonin in mated queens and higher levels of Mn and glucose in fertilized eggs suggested that these substances are very important for normal ovarian and embryonic growth. The different expression of three reproductive genes (vtgl, rabil and JHE1) suggested that they might be involved in the regulation of ovarian and embryonic growth. Overall, changes in these physiological indices may substantially affect ovarian and embryonic growth and prohibit the incubation of unfertilized eggs in R. chinensis.

Zoology↗

bioRxiv2016

When the Good Guy Becomes the Bad Boy: Social Information Modulates the Neural, Physiological and Subjective Responses to Emotional Facial Expressions

In the past decade, different studies have suggested that high-order factors could influence the perceptual processing of emotional stimuli. In this study, we aimed to evaluate the effect of congruent vs. incongruent social information (positive, negative or no information related to the character of the target) on subjective (perceived and felt valence and arousal), physiological (facial mimicry) as well as on neural (P100 and N170) responses to dynamic emotoional facial expressions (EFE) that varied from neutral to one of the six basic emotions. Across three studies, the results showed (1) reduced valence and arousal evaluation of EFE when associated with incongruent social information (Study 1), (2) increased electromyographical responses (Study 2) and significant modulation of P100 and N170 components (Study 3) when EFE were associated with social (positive and negative) information (vs. no information). These studies revealed that positive or negative social information reduced subjective responses to incongruent EFE and produces a similar neural and physiological boost of the early perceptual processing of EFE irrespective of their congruency. In conclusion, this study suggested that social context (positive or negative) enhances the necessity to be alert to any subsequent cues.

Neuroscience↗

bioRxiv2016

A unified coarse-grained theory of bacterial physiology explains the relationship between cell size, growth rate and proteome composition under various growth limitations

Universal observations in Biology are sometimes described as "laws". In E. coli, experimental studies performed over the past six decades have revealed major growth laws relating ribosomal mass fraction and cell size to the growth rate. Because they formalize complex emerging principles in biology, growth laws have been instrumental in shaping our understanding of bacterial physiology. Here, we discovered a novel size law that connects cell size to the inverse of the metabolic proteome mass fraction and the active fraction of ribosomes. We used a simple whole-cell coarse-grained model of cell physiology that combines the proteome allocation theory and the structural model of cell division. The model captures all available experimental data connecting the cell proteome composition, ribosome activity, division size and growth rate in response to nutrient quality, antibiotic treatment and increased protein burden. Finally, a stochastic extension of the model explains non-trivial correlations observed in single cell experiments including the adder principle. This work provides a simple and robust theoretical framework for studying the fundamental principles of cell size determination in unicellular organisms.

Biophysics↗

bioRxiv2017

The collective influence of 1, 25-dihydroxyvitamin D3 with physiological fluid shear stress on osteoblasts

1, 25-dihydroxyvitamin D3 (1, 25 (OH)2 D3) and mechanical stimuli in physiological environment play an important role in the pathogenesis of osteoporosis. The effects of 1, 25-dihydroxyvitamin D3 alone and mechanical stimuli alone on osteoblasts have been widely investigated. This study reports the collective influences of 1, 25-dihydroxyvitamin D3 and flow shear stress (FSS) on biological functions of osteoblasts. 1, 25 (OH)2 D3 were constructed in various kinds of concentration (0, 1, 10, 100 nmmol/L), while physiological fluid shear stress (12 dynes/cm2) were produced by using a parallel-plate fluid flow system. 1, 25 (OH)2 D3 affects the responses of ROBs to FSS, including the inhibition of NO releases and cell proliferation as well as the promotion of PGE2 releases and cell differentiation. These findings provide a possible mechanism by which 1, 25(OH)2 D3 influences osteoblasts responses to FSS and may provide guidance for the selection of 1, 25(OH)2 D3 concentration and mechanical loading in order to in vitro produce functional bone tissues.

cell biology↗

bioRxiv2019

Morphologically and physiologically diverse fruits of two Lepidium species differ in allocation of glucosinolates into immature and mature seed and pericarp

The morphology and physiology of diaspores play crucial roles in determining the fate of seeds in unpredictable habitats. In some genera of the Brassicaceae different types of diaspores can be found. Lepidium appelianum produces non-dormant seeds within indehiscent fruits while in L. campestre dormant seeds are released from dehiscent fruits. These different diaspore types offer an excellent model system to analyse the allocation of relevant defence compounds into different tissues, which may maximise diaspore fitness. Total glucosinolate concentration and composition were analysed in immature and mature seeds and pericarps of L. appelianum and L. campestre using high-performance liquid chromatography. Moreover, transgenic RNAi L. campestre lines were used for comparison that produce indehiscent fruits due to silencing of LcINDEHISCENCE, the INDEHISCENCE ortholog of L. campestre. Total glucosinolate concentrations were lower in green compared to mature seeds in all studied Lepidium species and transgenic lines. In contrast, indehiscent fruits of L. appelianum maintained their total glucosinolate concentration in mature pericarps compared to green ones, while in dehiscent L. campestre and in indehiscent RNAi-LcIND L. campestre a significant decrease in total glucosinolate concentrations from green to mature pericarps could be detected. Regarding the distribution of glucosinolate classes, high concentrations of 4-methoxyindol-3-ylmethyl glucosinolate were found in mature seeds of L. appelianum, while no indole glucosinolates were detected in mature diaspores of L. campestre. The diaspores of the latter species may rather depend on aliphatic and aromatic glucosinolates for long-term protection. The allocation patterns of glucosinolates correlate with the morpho-physiologically distinct fruits of L. appelianum and L. campestre and may be explained by the distinct dispersal strategies and the dormancy status of both species.

plant biology↗

bioRxiv2020

Granular Transcriptomic Signatures Derived from Independent Component Analysis of Bulk Nervous Tissue for Studying Labile Brain Physiologies

Multicellular organisms employ concurrent gene regulatory programs to control development and physiology of cells and tissues. The Drosophila melanogaster model system has a remarkable history of revealing the genes and mechanisms underlying fundamental biology yet much remains unclear. In particular, brain xenobiotic protection and endobiotic regulatory systems that require transcriptional coordination across different cell types, operating in parallel with the primary nervous system and metabolic functions of each cell type, are still poorly understood. Here we use the unsupervised machine learning method independent component analysis (ICA) on majority fresh-frozen, bulk tissue microarrays to define biologically pertinent gene expression signatures which are sparse, i.e. each involving only a fraction of all fly genes. We optimize the gene expression signature definitions partly through repeated application of a stochastic ICA algorithm to a compendium of 3,346 microarrays from 221 experiments provided by the Drosophila research community. Our optimized ICA model of pan fly gene expression consists of 850 modules of co-regulated genes that map to tissue developmental stages, disease states, cell-autonomous pathways and presumably novel processes. Importantly, we show biologically relevant gene modules expressed at varying amplitudes in whole brain and isolated adult blood-brain barrier cell levels. Thus, whole tissue derived ICA transcriptional signatures that transcend single cell type boundaries provide a window into the transcriptional states of difficult to isolate cell ensembles maintaining delicate brain physiologies. We believe the fly ICA gene expression signatures set, by virtue of the success of ICA at inferring robust often low amplitude patterns across large datasets and the quality of the input samples, to be an important asset for analyzing compendium and newly generated microarray or RNA-seq expression datasets.

bioinformatics↗

bioRxiv2020

A Physiological Characterization in Controlled Bioreactors Reveals a Novel Survival Strategy for Debaryomyces hansenii at High Salinity and Confirms its Halophilic Behavior

Debaryomyces hansenii is traditionally described as a halotolerant non-conventional yeast, being the model organism for the study of osmo- and salt tolerance mechanisms in eukaryotic systems for the past 30 years. However, unravelling of D. hanseniis biotechnological potential has always been difficult due to the persistent limitations in the availability of efficient molecular tools described for this yeast. Additionally, there is a lack of consensus and contradictory information along the recent years that limits a comprehensive understanding of its central carbon metabolism, mainly due to a lack of physiological studies in controlled and monitored environments. Moreover, there is controversy about the diversity in the culture conditions (media composition, temperature and pH among others) used by different groups, which makes it complicated when trying to get significant conclusions and behavioural patterns. In this work, we present for the first time a physiological characterization of D. hansenii in batch cultivations using highly instrumented and controlled lab-scale bioreactors. Our findings contribute to a more complete picture of the central carbon metabolism and the external pH influence on the yeast ability to tolerate high Na+ and K+ concentrations. Finally, the controversial halophilic/halotolerant character of this yeast is further clarified.

microbiology↗

bioRxiv2020

A standardized head-fixation system for performing large-scale, in-vivo physiological recordings in mice

BACKGROUNDThe Allen Institute recently built a set of high-throughput experimental pipelines to collect comprehensive in vivo surveys of physiological activity in the visual cortex of awake, head-fixed mice. Developing these large-scale, industrial-like pipelines posed many scientific, operational, and engineering challenges. NEW METHODOur strategies for creating a cross-platform reference space to which all pipeline datasets were mapped required development of 1) a robust headframe, 2) a reproducible clamping system, and 3) data-collection systems that are built, and maintained, around precise alignment with a reference artifact. RESULTSWhen paired with our pipeline clamping system, our headframe exceeded deflection and reproducibility requirements. By leveraging our headframe and clamping system we were able to create a cross-platform reference space to which multi-modal imaging datasets could be mapped. COMPARISON WITH EXISTING METHODSTogether, the Allen Brain Observatory headframe, surgical tooling, clamping system, and system registration strategy create a unique system for collecting large amounts of standardized in vivo datasets over long periods of time. Moreover, the integrated approach to cross-platform registration allows for multi-modal datasets to be collected within a shared reference space. CONCLUSIONSHere we report the engineering strategies that we implemented when creating the Allen Brain Observatory physiology pipelines. All of the documentation related to headframe, surgical tooling, and clamp design has been made freely available and can be readily manufactured or procured. The engineering strategy, or components of the strategy, described in this report can be tailored and applied by external researchers to improve data standardization and stability.

neuroscience↗

bioRxiv2020

Alterations in neuronal physiology, development, and function associated with a common duplication of chromosome 15 involving CHRNA7

BackgroundCopy number variants at chromosome 15q13.3 contribute to liability for multiple intellectual and developmental disabilities including Autism Spectrum Disorder (ASD). Individuals with duplications of this interval, which includes the gene CHRNA7, have multiple psychiatric disorders with widely variable penetrance. However, the basis of such differential affectation remains uncharacterized. MethodsInduced pluripotent stem cell (iPSC) models were generated from two first degree relatives with the same 15q13.3 duplication, a boy with distinct features of autism and emotional dysregulation (the affected proband, AP) and his clinically unaffected mother (the UM). These models were compared to unrelated control subjects lacking this duplication (UC, male and female). iPSC-derived neural progenitors and cortical neuroids consisting of cortical excitatory and inhibitory neurons were used to model potential contributors to neuropsychiatric impairment. ResultsThe AP-derived model uniquely exhibited disruptions of cellular physiology and neurodevelopment not observed in either the UM or the unrelated male and female controls. These included enhanced neural progenitor proliferation but impaired neuronal differentiation, maturation, and migration, and increased endoplasmic reticulum (ER) stress. Both the AP models neuronal migration deficit and elevated ER stress could be selectively rescued by different pharmacologic agents. Neuronal gene expression was also specifically dysregulated in the AP, including reduced expression of genes related to behavior, psychological disorders, neuritogenesis, neuronal migration, and WNT, axonal guidance, and GABA receptor signaling. Interestingly, the UM model exhibited upregulated expression of genes in many of these same pathways, by comparison with both the AP and UC models, suggesting that cell intrinsic molecular compensation could have contributed to the lack of neurodevelopmental phenotypes in the UM model. However, by contrast with the AP-specific neurodevelopmental phenotypes, both the AP- and UM-derived neurons exhibited shared alterations of neuronal function, including increased action potential firing and elevated cholinergic activity, consistent with increased homomeric CHRNA7 channel activity. ConclusionTogether, these data define both affectation-specific phenotypes seen only in the AP, as well as abnormalities observed in both individuals with CHRNA7 duplication, the AP and UM, but not in UC-derived neurons. This is, to our knowledge, the first study to use a human stem cell-based platform to study the basis of variable affectation in cases of 15q13.3 duplication at the cellular, molecular, and functional levels. This work suggests potential approaches for suppressing abnormal neurodevelopment or physiology that may contribute to severity of affectation. Some of these AP-specific neurodevelopmental anomalies, or the functional anomalies observed in both 15q13.3 duplication carriers (the AP and UM), could also contribute to the variable phenotypic penetrance seen in other individuals with 15q13.3 duplication.

developmental biology↗

bioRxiv2020

Measuring nucleus mechanics within a living multicellular organism: Physical decoupling and attenuated recovery rate are physiological protective mechanisms of the cell nucleus under high mechanical load

Nuclei within cells are constantly subjected to compressive, tensile and shear forces, which regulate nucleoskeletal and cytoskeletal remodeling, activate signaling pathways and direct cell-fate decisions. Multiple rheological methods have been adapted for characterizing the response to applied forces of isolated nuclei and nuclei within intact cells. However, in vitro measurements fail to capture the viscoelastic modulation of nuclear stress-strain relationships by the physiological tethering to the surrounding cytoskeleton, extracellular matrix and cells, and tissue-level architectures. Using an equiaxial stretching apparatus, we applied a step stress and measured nucleus deformation dynamics within living C. elegans nematodes. Nuclei deformed non-monotonically under constant load. Non-monotonic deformation was conserved across tissues and robust to nucleoskeletal and cytoskeletal perturbations, but it required intact Linker of Nucleoskeleton and Cytoskeleton (LINC) complex attachments. The transition from creep to strain recovery fits a tensile-compressive linear viscoelastic model that is indicative of nucleoskeletal-cytoskeletal decoupling under high load. Ce-lamin (lmn-1) knockdown softened the nucleus whereas nematode ageing stiffened equilibrium elasticity and decreased deformation recovery rate. Recovery lasted minutes due to physiological damping of the released mechanical energy thus protecting nuclear integrity and preventing chromatin damage.

cell biology↗

bioRxiv2020

Altered spike timing-dependent plasticity rules in physiological calcium

Like many forms of long-term synaptic plasticity, spike-timing-dependent plasticity (STDP) depends on intracellular Ca2+ signaling for its induction. Yet, all in vitro studies devoted to STDP used abnormally high external Ca2+ concentration. We measured STDP at the CA3-CA1 hippocampal synapses under different extracellular Ca2+ concentrations and found that the sign, shape and magnitude of plasticity strongly depend on Ca2+. A pre-post protocol that results in robust LTP in high Ca2+, yielded only LTD or no plasticity in the physiological Ca2+ range. LTP could be restored by either increasing the number of post-synaptic spikes or increasing the pairing frequency. A calcium-based plasticity model in which depression and potentiation depend on post-synaptic Ca2+ transients was found to fit quantitatively all the data, provided NMDA receptor-mediated non-linearities were implemented. In conclusion, STDP rule is profoundly altered in physiological Ca2+ but specific activity regimes restore a classical STDP profile.

neuroscience↗

bioRxiv2020

Revealing 29 sets of independently modulated genes in Staphylococcus aureus, their regulators and role in key physiological responses

The ability of Staphylococcus aureus to infect many different tissue sites is enabled, in part, by its Transcriptional Regulatory Network (TRN) that coordinates its gene expression to respond to different environments. We elucidated the organization and activity of this TRN by applying Independent Component Analysis (ICA) to a compendium of 108 RNAseq expression profiles from two S. aureus clinical strains (TCH1516 and LAC). ICA decomposed the S. aureus transcriptome into 29 independently modulated sets of genes (i-modulons) that revealed (1) high confidence associations between 21 i-modulons and known regulators; (2) an association between an i-modulon and {sigma}S, whose regulatory role was previously undefined; (3) the regulatory organization of 65 virulence factors in the form of three i-modulons associated with AgrR, SaeR and Vim-3, (4) the roles of three key transcription factors (codY, Fur and ccpA) in coordinating the metabolic and regulatory networks; and (5) a low dimensional representation, involving the function of few transcription factors, of changes in gene expression between two laboratory media (RPMI, CAMHB) and two physiological media (blood and serum). This representation of the TRN covers 842 genes representing 76% of the variance in gene expression that provides a quantitative reconstruction of transcriptional modules in S. aureus, and a platform enabling its full elucidation. Significance StatementStaphylococcus aureus infections impose an immense burden on the healthcare system. To establish a successful infection in a hostile host environment, S. aureus must coordinate its gene expression to respond to a wide array of challenges. This balancing act is largely orchestrated by the Transcriptional Regulatory Network (TRN). Here, we present a model of 29 independently modulated sets of genes that form the basis for a segment of the TRN in clinical USA300 strains of S. aureus. Using this model, we demonstrate the concerted role of various cellular systems (e.g. metabolism, virulence and stress response) underlying key physiological responses, including response during blood infection.

microbiology↗

bioRxiv2020

Varietas delectat: groups with diverse personalities mitigate physiological stress in a songbird

Social groups often consist of diverse phenotypes, including personality types, and this diversity is known to affect the functioning of the group as a whole. Social selection theory proposes that group composition (i.e. social environment) also influences the performance of individual group members. However, the effect of group behavioural composition on group members remains largely unexplored, and it is still contentious whether individuals benefit more in a social environment with homogeneous or diverse behavioural composition. We experimentally formed groups of house sparrows Passer domesticus with high and low diversity of personality (exploratory behaviour), and found that their physiological state (body condition, physiological stress and oxidative damage) improved with increasing group-level diversity of personality. These findings demonstrate that group personality composition affects the condition of group members and individuals benefit from social heterosis (i.e. associating with a diverse set of behavioural types). This aspect of the social life can play a key role in affiliation rules of social animals and might explain the evolutionary coexistence of different personalities in nature.

ecology↗

bioRxiv2020

Big dairy data to disentangle the effect of geo-environmental, physiological and morphological factors on milk production of mountain-pastured Braunvieh cows

1. SummaryThe transhumance system, which consists in moving animals to high mountain pastures during summer, plays a considerable role in preserving both local biodiversity and traditions, as well as protecting against natural hazard. In cows, particularly, milk production is observed to decline as a response to food shortage and climatic stress, leading to atypical lactation curves that are barely described by current lactation models. Here, we relied on five million monthly milk records from over 200,000 Braunvieh and Original Braunvieh cows to devise a new model accounting for transhumance, and test the influence of environmental, physiological, and morphological factors on cattle productivity. Counter to expectations, environmental conditions in the mountain showed a globally limited impact on milk production during transhumance, with cows in favourable conditions producing only 10% less compared to cows living in adverse conditions, and with precipitation in spring and altitude revealing to be the most production-affecting variables. Conversely, physiological factors as lactation number and pregnancy stage presented an important impact over the whole lactation cycle with 20% difference in milk production, and may therefore alter the way animals respond to transhumance. Finally, the considered morphological factors (cow height and foot angle) presented a smaller impact during the whole lactation cycle (10% difference in milk production). The present findings can help farmers to establish sustainable strategies for alleviating the negative effects of transhumance on productivity and preserving this important livestock practice.Competing Interest StatementThe authors have declared no competing interest.View Full Text

zoology↗

bioRxiv2020

Physiological diversity enhanced by recurrent divergence and secondary gene flow within a grass species

O_LIC4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this single species encompasses C4 and non-C4 populations. C_LIO_LIUsing phylogenomics and population genomics, we infer the history of dispersal and secondary exchanges before, during, and after photosynthetic divergence in A. semialata. We further establish the genetic origins of polyploids in this species. C_LIO_LIOrganelle phylogenies indicate limited seed dispersal within the Central Zambezian region of Africa, where the species originated [~] 2-3 Ma. Outside this region, the species spread rapidly across the paleotropics to Australia. Comparison of nuclear and organelle phylogenies and analyses of whole genomes reveal extensive secondary gene flow. In particular, the genomic group corresponding to the C4 trait was swept into seeds from distinct geographic regions. Multiple segmental allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. C_LIO_LILimited dispersal and isolation allowed lineage divergence, while episodic secondary exchanges led to the pollen-mediated, rapid spread of the derived C4 physiology. Overall, our study suggests that local adaptation followed by recurrent secondary gene flow promoted physiological diversification in this grass species. C_LI

evolutionary biology↗