Sex ratio plays a critical role in population survival. Dioecious plants may simultaneously display sexual dimorphism and deviations from the equilibrium expectation of 1:1 sex ratio in populations, that is, biased sex ratio. However, whether biased sex ratios can be attributed to sexual dimorphism has not been well investigated. Here, we conducted experiments using a three-water-depth gradient to examine sexual dimorphism performance and population sex ratios for Vallisneria natans, and investigated the variations in natural population sex ratios for it and two other congeners V. spinulosa and V. denseserrulata along water depth changes. Females of V. natans had higher reproductive investment than males, and the degree of sexual dimorphism increased with increasing water depth. At greater water depths, increased reproductive expenditure led to higher mortality in females, resulting in a male-biased sex ratio. The sex ratios of natural V. natans and V. spinulosa populations did not significantly deviate from 1:1. In contrast, populations of V. denseserrulata exhibited markedly a female-biased sex ratio, which may be attributed to female plants producing more clonal ramets. Furthermore, no evidence was found for variation in sex ratios along water depth gradients in natural populations of any of the three species. These findings highlight the plasticity both of sexual dimorphism and sex ratios in dioecious plants, indicating that sex ratios are species-specific and depend on sex-specific life-history strategy shaped by their growth environments.

East Asia has been hypothesized to be separated into distinct northern and southern regions by a climatic barrier, which is an east–west-oriented arid zone at approximately 40° N in eastern China. However, the impacts of climate change and local environmental selection on widespread species in this area are still poorly understood. In this study, we generated extensive genomic data for the crop pest Aelia fieberi (Hemiptera: Pentatomidae), which was sampled across its entire distribution in China, and we used these data in combination with niche analyses to investigate its phylogeographic pattern and examine the impact of climate change on its population structure and demographic history. We found that A. fieberi comprised two genetic lineages (southern and northern) that diverged during the middle Pleistocene, leading to a distinct “south–north” genetic pattern; this divergence was probably triggered by Pleistocene climate change in the arid belt. The two lineages of A. fieberi both experienced population expansion after the Last Interglacial (LIG) until the Last Glacial Maximum (LGM) and experienced secondary contact in the late Pleistocene. Local environmental adaptation may play an important role in maintaining and/or reinforcing the south–north divergence. Our study provides a detailed example of how climatic barriers and local environmental selection collaborate to facilitate adaptation to heterogeneous landscapes in East Asia from a phylogeographic perspective.

Ectomycorrhizal (ECM) fungi form symbiotic relationships with woody plants, completing their life cyclesthrough mutualistic associations. The evolution of this symbiosis involves genomic adaptations including gene gain andloss. However, how these genomic characteristics reflect speciation and adaptation throughout the evolutionaryhistory of ECM fungi remains unclear. In the present study, we explored speciation and host adaptation in Tricholoma species, an ecologically relevant clade of ECM basidiomycetes. We compared the genomes of three species, Tricholoma matsutake, T. populinum, and T. bakamatsutake, which despite their close phylogenetic relationships, have different tree hosts. A phylogenetic tree constructed using single‐copy orthologous genes estimated the divergence time of T. populinum to be approximately 28.48 Mya, coinciding with the diversification of subg. Eupopulus in East Asia. The split between T. matsutake and T. bakamatsutake was estimated at around 8.08 Mya, corresponding to the diversification period of evergreen broadleaved forests in East Asia. In this study, we identified 19, 13, and 13 positively selected genes in the genomes of T. bakamatsutake, T. matsutake, and T. populinum, respectively. Additionally, 2983, 2783, and 1548 genes have undergone rapid evolution in their genomes. Gene ontology enrichment analysis revealed the functions of these rapidly evolving genes, including those associated with cell cycle, cytoplasmic components, and GTPase mediation. Gene flow analysis indicated unidirectional migration from the ancestor of T. populinum to T. matsutake and T. bakamatsutake, whereas bidirectional gene flow was observed in the ancestors of T. matsutake and T. bakamatsutake. This study suggested that host‐induced immigrant unviability in symbiotic fungi is the primary causeof prezygotic isolation. The combination of ecology‐based genomic evidence and gene flow analysis offers new insightinto the speciation and evolutionary mechanisms of symbiotic fungi.

The genetic structure and population history of ethno-linguistically diverse populations from the Yunnan–Guizhou Plateau remain underrepresented in human genomic research. We analyzed genome-wide data from 239 individuals in Guizhou, combined with modern and ancient datasets, to investigate their fine-scale genetic structure, demographic events, and functional consequences of adaptive genomic signatures. Our findings revealed three genetically distinct groups corresponding to linguistic categories, shaped by differential gene flow from ancient millet farmers and southern Chinese populations. We identified population-specific adaptive candidate genomic regions associated with immune, metabolic, and hematological functions. Additionally, we detected clinically relevant variants with implications for disease risk prediction and precision medicine. These findings underscore the importance of genetic diversity in understanding human adaptation and health disparities, offering a framework for equitable genomic research in underrepresented populations.

The maintenance of species boundaries between widespread and narrow endemic congeneric species in sympatric sites remains a fundamental question in ecology and evolutionary biology. For plants with specialized pollination mechanisms, pre- and postpollination isolation mechanisms likely play distinct roles in reproductive isolation and species integrity. Parnassia (Celastraceae) is characterized by one-by-one stamen movement and has its distribution center in southwest China, where many widespread and local endemic species coexist. To quantify pre- and postpollination barriers and their relative roles in maintaining species boundaries, we conducted field experiments with the widespread Parnassia wightiana Wall. ex Wight & Arn. and the local endemic Parnassia amoena Diels over two separate years at Jinfo Mountain, southwest China. We examined four prepollination barriers (ecogeography, blooming phenology, stamen movement, and pollinator type) and three postpollination barriers (fruit set, seed production, and seed viability). Our findings indicate that prepollination barriers played a more significant role in reproductive isolation than postpollination barriers. For the widely distributed P. wightiana, ecogeographical isolation was the primary barrier, followed by phenology and pollinator type isolation. In the narrow endemic P. amoena, which exhibits slower stamen movement, this feature contributed significantly to isolation, with phenological isolation being the second most important factor. Among postpollination barriers, seed viability was the most significant for both species. Our results indicate that prepollination barriers are the predominant isolation mechanism for these two sympatric Parnassia species, and stamen movement may serve as a novel type of prepollination barrier, particularly for the narrow endemic species.

Floral color and odor serve as attractants for pollinators. It remains unclear how changes in these traits in color-change species interact with pollinators and impact a plant's reproductive success. Lonicera calcarata flowers change from white (Night 1 [N1] and Day 1 [D1]) through yellow (Night 2 [N2]) and orange (Day 2 [D2]) to orange-red (Night 3 [N3] and Day 3 [D3]). Our research showed that floral characters, stigma activity, nectar production and floral spectral reflectance decreased through the flowering phases. Floral odor mainly comprised fatty acids, aldehydes, monoterpenes and alcohols, especially n-hexadecanoic acid, hexadecanal and 3-carene. Floral odor peaked on N1 and N3, largely due to the presence of fatty acids. The emission of n-hexadecanoic acid was higher on N1 and N3 compared with other phases, while hexadecanal emission remained constant throughout the flowering stages. The emission of 3-carene was highest on N1. Lonicera calcarata was mainly pollinated by the moth Chorodna strixaria, the butterfly Acosmeryx naga and three bumblebees (Bombus melanurus, B. eximius, B. sonani) and they all preferred to visit white (younger) flowers. Moths had a preference for 3-carene and no significant preference for n-hexadecanoic acid and hexadecanal. Seed sets of nocturnal pollination and control treatments were not significantly different. Lonicera calcarata could produce seeds by self-pollination; cross-pollination significantly increased the seed set. Floral color guides pollinators to visit younger flowers with more floral rewards and higher stigma activity. Different chemical compounds in floral odor may not only attract pollinators but also avoid herbivore damage.

An underlying assumption for the size-dependent sex allocation (SDS) hypothesis is that the plasticity of bisexual investments in hermaphrodites would be larger in female than in male allocation, but it has rarely been critically evaluated. Among five sexual morphs in a sexually polymorphic desert herb Geranium transversale, gynomonoecious individuals were the largest, and males were the smallest, while hermaphroditic and andromonoecious plants and females did not differ significantly in plant size. The total number of flowers increased with plant size in all five sexual morphs; in gynomonoecious and andromonoecious plants this was due to an increase in the number of perfect flowers rather than pistillate or staminate flowers. Flower size increased with plant size in hermaphroditic and gynomonoecious plants (due to an increase in the size of perfect but not of unisexual flowers). The sizes of staminate flowers in andromonoecious and male plants, and pistillate flowers in gynomonoecious plants did not increase with plant size, and pistil mass increased but stamen mass decreased with plant size. The coefficient of variation (CV) in pistil and stamen mass among 210 plants in four of the sexual morphs (excluding female plants) indicated that variation in resource allocation among individuals was higher in female than male functions. Both flower number and flower size generally increased with plant size in G. transversale, supporting the SDS hypothesis. The relatively higher plasticity (CV) in female than male allocation has not been reported before, providing a cue for understanding why the female-biased allocation associated with plant size is popular in flowering plants.

Allopolyploidy, involving whole genome duplication (WGD) of interspecific hybrids, is a driving force in the evolution of angiosperms, and has provided favored substrates for the domestication of major agricultural crops. This suggests allopolyploidy is a rich source of genetic variation amenable to natural and artificial selection. While allopolyploidy-induced chromosomal variation is common, its immediate phenotypic effects are challenging to delineate due to the confounding influence of postpolyploidy evolution. Newly constructed allopolyploids, having not yet undergone evolution, present suitable systems to address this issue. In this study, we synthesized five sets of allotetraploids, each with a unique genome constitution of S*S*DD, comprising a common paternal (DD) but distinct maternal (S*S*) parental diploid species of Aegilops. We observed that, except for one sterile synthetic allotetraploid, the remaining four allotetraploids exhibited high fertility, enabling the establishment of sexual lineages through selfing. Chromosomal variation in both number and structure occurred extensively, demonstrating moderate (though variable) effects on key morphological traits related to growth, development, and reproductive fitness of the nascent allotetraploids. All four sets of fertile allotetraploids can be crossed with bread wheat to generate pentaploid F1 hybrids, which as maternal parents can be further backcrossed to bread wheat. This approach promises a feasible strategy for the concomitant introgression of the vast repertoire of genetic variation from the D- and each of the four S* genome-containing species to bread wheat.

Gene loss is a widespread phenomenon in species evolution, yet the evolutionary significance of large-scale gene loss—whether arising through neutral processes or adaptive evolution—remains a subject of ongoing debate. Agaricus bisporus, a globally distributed macrofungus, serves as an ideal model to investigate this phenomenon. Utilizing the “map-to-pan” method, we constructed a high-resolution pangenome comprising 30 793 genes and 143 Mb of additional sequences, including 21 370 genes absent in the reference genome. Phylogenetic and admixture analyses identified four genetic lineages: the globally distributed MIX and region-specific European, America, and Highland lineages. Core gene analyses revealed a substantially lower genetic load in MIX lineage, accompanied by a marked reduction in the frequency of deleterious mutations compared with other lineages. Presence–absence variation (PAV) analyses further demonstrated extensive gene loss in MIX lineage, with functional enrichment analyses associating these PAVs with DNA damage repair pathways. This finding suggests that gene loss could enhance tolerance to DNA damage, thereby mitigating mutation accumulation. A significantly higher proportion of lost PAVs in MIX lineage was under selective pressure, supporting gene loss as an adaptive strategy. Our findings highlight two key mechanisms facilitating the MIX lineage's broad distribution: (1) the reduction of deleterious mutations, thereby lowering genetic load, and (2) the selective loss of redundant, non-essential genes, enhancing adaptability across diverse environments. This study not only underscores the adaptive significance of large-scale gene loss in the evolution of A. bisporus but also offers a broader framework for understanding how gene loss events shape the evolutionary trajectories of other fungal species.

Organisms exhibit diverse responses when exposed to novel environments, and successful adaptation depends on aligning evolutionary histories with these new conditions. Reusing standing genetic variation is a critical mechanism for this adaptation process. Using an extended Fisher's geometric model, we conducted simulations of evolving populations to investigate how evolutionary histories influence adaptation to novel environments. Our results highlight that distinct evolutionary histories produce varying patterns of genetic variance within populations. When organisms return to previously experienced environments, they exhibit enhanced performance and rapid adaptation. This supports the validity of the strategy commonly employed in ecological restoration to revert habitats to their original state. Moreover, small deviations of the greatest genetic variance direction from the optimum are beneficial for both fitness and fitness increase. A small genetic variance size is advantageous for fitness but impedes fitness increase. A short distance to the optimum and a sharp genetic variance shape are beneficial for fitness but have no significant effects on fitness increase. Our findings underscore the crucial role of evolutionary histories in shaping genetic variance and evolutionary potential when adapting to a new optimum. These results contribute to an evolutionary understanding of the factors underlying the disparate responses of phenotypically similar species to environmental change.

Coping with increasing global temperatures due to climate change may be especially challenging for trees with long generation times as changes might happen too quickly for successful adaptation. Juniperus przewalskii Komarov is an arid tolerant key species of forest ecosystems on the northeastern Qinghai–Tibet Plateau. Target capture sequencing was utilized to survey genetic variation and population structure, and to infer the evolutionary history of this species by analyzing 170 individuals from 23 populations. This approach provided valuable information on how local adaptation influences the genetic background of this species, as well as potential predictions regarding the species' response to global climate change. Our results revealed a new fine‐scale genetic structure and high levels of genetic diversity as well as local adaptations despite gene flow. Redundancy analysis showed that climate contributed the most to the genetic variation of J. przewalskii. Analysis of gradient forest and risk of nonadaptedness indicated that, for the variables examined and the majority of locations sampled, it is improbable that J. przewalskii will need significant alterations in allele frequencies to endure the forecasted climate shifts. We also identified the most at‐risk populations for preservation and numerous candidate genes that may be valuable for upcoming climate change. The significance of combining genetic and environmental information to forecast the resilience of a key tree species to global warming is underscored in our results, particularly in areas susceptible to climate fluctuations.

Taihangia rupestris Yu & Li, an early spring flowering plant of the Rosaceae family, is classified as a second-level protected species in China. Endemic to the cliff faces of the Taihang Mountains in central China, this rare species requires a comprehensive understanding and conservation approach. In this study, we analyzed population-level genetic variations in both chloroplast and nuclear genomes. Taihangia rupestris var. ciliata exhibited higher genetic diversity than T. rupestris var. rupestris in both genome types. All individuals of T. rupestris var. rupestris formed a single cluster, while individuals of T. rupestris var. ciliata were grouped into three distinct clusters. Approximately 29.82 Ma, T. rupestris diverged from its closely related species. Taihangia rupestris var. ciliata appeared first, followed by the differentiation of T. rupestris var. rupestris, which adapted to the climate of the southern Taihang Mountains, around 3.55 Ma. Additionally, our study identified several chloroplast genes potentially involved in variety adaptive differentiation. These findings enhance our understanding of environmental adaptation and differentiation in the two T. rupestris varieties, providing valuable genetic insights for the conservation and utilization of this species.

A full understanding of local adaptation at the genomic level will help to elucidate its role in the differentiation between closely related species. This study focused on rice seed bugs sister species (Leptocorisa chinensis and Leptocorisa oratoria), which are native to East Asia and are notorious pests targeting growing rice spikelets. East Asia is a region where diverse geology and fluctuating climate are known to have profound impacts on organisms. In this study, single nucleotide polymorphisms (SNPs) from double-digest restriction site-associated DNA sequencing and geographic distribution information were used to investigate phylogeography and assess the environmental contribution to genetic variation. We found clear genetic differentiation between sister species, but a lack of genetic structure within species because of their long-distance dispersal ability. The demographic model involved a scenario in which divergence in isolation (~0.6 Ma) was followed by secondary contact (~7 kya). The initial divergence may have been caused by the intensification of the East Asian monsoon during the Pleistocene climate oscillation. The historical demography indicated that the effective population size (N_e) showed an evident increase from 9 to 7 kya, which may be related to rice domestication and extensive human cultivation during the Holocene. We also detected a significant correlation between genetic and environmental distance, and the niche difference occupied between them. Temperature-related variables were ranked as the main factors for the difference, and 410 selective SNPs involved in adaptation were identified. The Nanling Mountains in southern China serve as a geographical boundary between them and act as an ecological barrier belt that promotes local environmental adaptation. Our study demonstrates that historical climate change and local adaptation by climate-imposed selection shape the phylogeographical patterns of sister species.

Speciation events often occur with adaptive radiation. The factors that promote these adaptive radiating species diversity patterns have intrigued biologists for more than a century. In the present study, we used the adaptive radiated genus Ligustrum to evaluate the relative contributions of the environment, species interactions, phylogenetic diversity, and diversification rates in generating extant species diversity patterns. Using complete chloroplast genome data, we reconstructed the highly supported and dated backbone phylogenetic relationships of Ligustrum. Biogeographic results indicated that Ligustrum originated in Southwest China during the Oligocene and spread to suitable areas that were warm and humid via 18 dispersal events. For the overlapping ranges of species pairs, a smaller phylogenetic distance was detected in high species overlap than in low species overlap, which is consistent with no significant difference in niche among the different species. We found that the phylogenetic diversity and interspecies competition induced by insignificant niche divergence shaped the global pattern of Ligustrum diversity.

Rhododendron is a significant plant genus, with over 600 identified species in China. The subgenus Hymenanthes holds the largest number of Rhododendron germplasms and showcases strong environmental adaptability. However, there remains a lack of understanding regarding Rhododendron's evolution and environmental adaptations. Rhododendron bailiense Y.P.Ma, C.Q.Zhang & D.F.Chamb., an exceedingly rare species, thrives in the alkaline karst landforms of Guizhou, southwest China, different from the typical growing environment of other Rhododendron species. In this study, we present a chromosome-level genome assembly of R. bailiense, revealing a genome size of 923.3 Mb, a contig N50 of 24.5 Mb, and a total of 47 567 predicted genes. An evolutionary analysis indicated that R. bailiense diverged from its ancestors prior to the other subgenus Hymenanthes rhododendrons, with the expanded and contracted genes being notably enriched in “stress response” and “growth,” respectively. Rhododendron bailiense is predominantly found on limestone soil in the mountains of Guizhou, with only two wild populations known. The genome of R. bailiense contained a high copy number of ankyrin repeat (ANK) and Ca²⁺-ATPase (CAP) genes, primarily involved in Ca²⁺ transport, shedding light on how R. bailiense copes with karst high-calcium stress. In contrast, the structures of the ANKs displayed unique characteristics, while the CAPs showed conservatism. The R. bailiense genome provides new insights into the adaptation and evolutionary history of Rhododendron plants in karst environments, potentially offering valuable information for adaptive breeding and ecological enhancement in such challenging settings.

Adaptive radiation is usually triggered by great in situ or ex situ environmental changes. How an adaptive radiation occurs on lands and how species richness relates to morphodisparity have been a major focus of evolutionary biology. Petrocodon, diversified in the southeastern Qinghai–Tibet Plateau (QTP), represents an ideal model to address these questions. To elucidate the dynamics of adaptive radiation of Petrocodon, we took an integrative approach, including phylogenetic, dating, disparity versus diversity, pollination, and gene expression analyses. Petrocodon with six clades has experienced radiation following the QTP uplift. Multiple modes of floral morphodisparity versus species diversity occur in the radiation process that are directly linked to their colonizing new environments and diversification with geographic expansion. Pollination and gene expression analyses suggest that accelerated emergence of de novo mutations might be relevant to the multiplex floral disparity and pollinator shifts in Petrocodon. For the first time in plants, we report that decreased genetic constraints on floral architecture triggered by QTP uplift might have generated abundant floral morphological variants, which were further targeted by selection for ecological divergence. The multiple modes of floral disparity versus species diversity may be attributed to accelerated mutations in colonizing new environments and repeated modifications of the already evolved traits in subsequent diversification and geographic expansion in Petrocodon. Our findings shed novel light on the interplay of ecological, developmental and evolutionary dynamics of disparity versus diversity in relation to trajectory changes of floral architecture in responses to environmental disturbance in a terrestrial plant group.

In the Mountains of Southwest China (MSC), accelerated diversification triggered by mountain uplift and monsoon intensification in the Miocene is widely revealed, but less is known about the stage after the Pliocene. Thus, the tempo‐spatial evolution of the endemism of Gaoligong Shan (GLGS), a young and isolated mountain with the highest biodiversity in the MSC, was determined. Temporal patterns were inferred by the stem ages of the endemic species and spatial patterns were inferred through ancestral area reconstructions and the distributions of the sister taxa. Temporally, the calibrated origin times of 114 phylogenetically well resolved endemic species (75 plants, 33 animals and six fungi) ranged from the early Miocene to the Holecene. Spatially, 82 centric origin species (mean = 3.08 Ma) were significantly younger than 32 eccentric origin species (6.84 Ma). Eccentric origins accumulated smoothly while centric origins burst after the late Pliocene, especially after the Pleistocene (n = 52). In centric origins, most of the sister taxa showed sympatric (n = 47) or allopatric (n = 23) distributions in the GLGS. The eccentric origins were mainly dispersed from the southern lower latitude region (n = 20). Principle component analysis indicated that niche conservatism exerted greater contribution to the speciation of the endemic species. Uplift of the GLGS and monsoon intensification during the late Pliocene accelerated the formation of its endemism. The “Species pump” effect of the Pleistocene climatic fluctuations is further revealed. Speciation triggered by geological isolation by mountain and river barriers through niche conservatism exceeds adaptive evolution.

Plants exhibiting different growth forms possess different capabilities in adapting to their respective environments, consequently displaying distinct geographical patterns of phylogenetic relatedness across a broad environmental gradient. Here, we compare the geographical patterns of phylogenetic relatedness between woody and herbaceous angiosperms in China, based on three phylogenetic relatedness metrics, namely, the standardized effect sizes of phylogenetic diversity (PD_ses), mean pairwise distance (MPD_ses), and mean nearest taxon distance (MNTD_ses). Additionally, we explore the effects of three categories of environmental variables (current climate, historical climate change, and environmental heterogeneity) on the geographical patterns of phylogenetic relatedness of both plant groups. Our results indicate that the geographical patterns of phylogenetic relatedness of herbaceous and woody plants are inconsistent, and the deviations of phylogenetic relatedness between woody and herbaceous angiosperms have geographical patterns and vary along environmental gradients. Our study found that environmental variables have a greater influence on the phylogenetic relatedness of herbaceous plants than on that of woody plants, emphasizing that environmental variables, especially current climatic variables, are the primary drivers of the deviations of phylogenetic relatedness between woody and herbaceous angiosperms. In summary, we illustrate the distinct differences in phylogenetic relatedness among plants of different growth forms, providing valuable insights into the driving factors of species coexistence at various spatial scales.

Jujube (Ziziphus jujuba Mill.), renowned for its nutritional value and health benefits, is believed to have originated in the middle and lower reaches of the Yellow River in China, where it underwent domestication from wild jujube. Nonetheless, the evolutionary trajectory and species differentiation between wild jujube and cultivated jujube still require further elucidation. The chloroplast genome (plastome), characterized by its relatively lower mutation rate compared to the nuclear genome, serves as an excellent model for evolutionary and comparative genomic research. In this study, we analyzed 326 nonredundant plastomes, encompassing 133 jujube cultivars and 193 wild jujube genotypes distributed throughout China. Noteworthy variations in the large single copy region primarily account for the size differences among these plastomes, impacting the evolution from wild jujube to cultivated varieties. Horizontal gene transfer (HGT) unveiled a unique chloroplast-to-nucleus transfer event, with transferred fragments predominantly influencing the evolution of the nuclear genome while leaving the plastome relatively unaffected. Population genetics analysis revealed two distinct evolutionary pathways from wild jujube to cultivated jujube: one driven by natural selection with minimal human interference, and the other resulting from human domestication and cultivation. Molecular dating, based on phylogenetic analysis, supported the likelihood that wild jujube and cultivated jujube fall within the same taxonomic category, Z. jujuba. In summary, our study comprehensively examined jujube plastome structures and HGT events, simultaneously contributing novel insights into the intricate processes that govern the evolution and domestication of jujube species.

Elucidating how plant species respond to variable light conditions is essential to understanding the ecological adaptation to heterogeneous environments. Plant performance and gene regulatory network underpinning the adaptation have been well documented in heliophytic species. However, it remains largely unclear how the sciophytic plants respond to distinct light conditions. We measured phenotypic and transcriptomic features of four sciophytic (Fatsia japonica, Metapanax delavayi, Heptapleurum arboricola, and Heptapleurum delavayi) and one heliophytic woody species (Tetrapanax papyrifer) of the Araliaceae family under distinct light conditions. Our phenotypic comparisons demonstrate that the four sciophytic species maintain similar photosynthesis efficiency between high light and low light conditions. However, a significantly decreased photosynthesis rate was observed under the low light conditions of the heliophytic species compared with the high light conditions. In addition, our leaf anatomical analyses revealed that, while all five species showed different anatomical structures under distinct light conditions, the sciophytic species possessed a lower degree of phenotypic plasticity relative to the heliophytic species. Further comparisons of the transcriptome profiling showed that differentially expressed genes identified in the five species were functionally related to photosynthesis, secondary metabolites, and other basic metabolisms. In particular, differential regulation of the photosynthesis-related and photomorphogenesis-related genes were potentially correlated with the phenotypic responses to the distinct light conditions of the five species. Our study provides evolutionary and ecological perspectives on how the heliophytic and sciophytic woody species respond to shade and sunlight environments.

Rubisco is assembled from large subunits (encoded by chloroplast gene rbcL) and small subunits (encoded by the nuclear rbcS multigene family), which are involved in the processes of carbon dioxide fixation in the Calvin cycle of photosynthesis. Although Rubisco has been studied in many plants, the evolutionary divergences among the different rbcS genes are still largely unknown. Here, using a rice closely related wild species, Oryza punctata Kotschy ex Steud, we investigated the differential properties of the rbcS genes in the species. We identified five rbcS genes (OprbcS1 through OprbcS5), OprbcS1 showed a different evolutionary pattern from the remaining four genes in terms of chromosome location, gene structure, and sequence homology. Phylogenetic analysis revealed that plant rbcS1 and other non-rbcS1 genes originated from a common ancient duplication event that occurred at least in seed plants ancestor. RbcS1 was then retained in a few plant lineages, including Oryza, whereas non-rbcS1 was mainly amplified in angiosperms. OprbcS1, OprbcS2–OprbcS4, and OprbcS5 were prominently expressed in stems and seeds, young leaves, and mature leaves, respectively. The yeast two-hybrid assay detected a significant decrease in the interaction between OprbcS1 and OprbcL compared to the other four pairs of proteins (OprbcS2–OprbcS5 and OprbcL). We propose that OprbcS1 might be assigned a divergent function that was predominantly specific to nonphotosynthetic organs, whereas OprbcS2–OprbcS5, having different affinity in the assembly process of Rubisco, might be subfunctionalized in photosynthetic organs. This study not only deepens our understanding of the fine assembly of Rubisco, but also sheds some light on future de novo domestication of wild rice.

Both hybridization and intraspecific morphological variation across environmental gradients complicate species delineation. We aimed to discern both possibilities that may blur species boundaries in the Carpinus viminea-Carpinus laxiflora-Carpinus londoniana species complex. We conducted statistical analyses on 535 specimens encompassing the entire distribution of this species complex to identify phenotypic clusters. Additionally, we analyzed genetic divergence and probable hybridization between clusters using 76 individuals from 37 populations. Based on phenotypic and genetic clusters, we tentatively recognized four species: C. viminea, C. fargesii, C. laxiflora, and C. londoniana. Except for rare overlapping distributions between C. fargesii and C. londoniana, the redefined four species are mostly allopatric to each another based on their distributions. The morphological delimitation, species boundary and distribution of each species differ distinctly from past taxonomic treatments. For example, specimens previously identified under C. viminea, in fact, belong to three different species. Hybrids between C. fargesii and C. londoniana exhibit morphological traits similar to C. viminea, thereby contributing to difficulties in determining species boundaries and outlining species distributions. These findings suggest that local selection and geographical isolation may together have promoted both phenotypic and genetic divergences within this species complex. However, interspecific hybridization blurs species boundaries by producing hybrids with phenotypic similarity in addition to intraspecific variation. This study emphasizes the importance of statistical analyses of population-level morphological and genetic variations across major distributional ranges for an integrative delimitation of species boundaries and the identification of hybridization and hybrids.

The soil-nitrogen condition, which differs greatly between paddy fields (mainly in the form of ammonium, NH₄⁺) and dry fields (mainly in the form of nitrate, NO₃^-), is a main environmental factor that drives the adaptive differentiation between upland and lowland rice ecotypes. However, the adaptive differentiation in terms of the nitrogen use efficiency (NUE) between upland and lowland rice has not been well addressed. In this study, we evaluated NUE-related traits among rice landraces as well as the genetic differentiation between NUE- associated genes and quantitative trait loci (QTLs). The japonica upland and lowland rice ecotypes showed large differences in their NUE-related traits such as the absorption ability for NH₄⁺ and NO₃^-. The indica upland and lowland rice exhibited similar performances when cultivated in solutions containing NH₄⁺ or NO₃^- or when planted in paddy or dry fields. However, the indica upland rice possessed a greater ability to absorb NO₃^-. We identified 76 QTLs for 25 measured traits using genome-wide association analysis. The highly differentiated NUE- associated genes or QTLs between ecotypes were rarely shared by japonica and indica subspecies, indicating an independent genetic basis for their soil-nitrogen adaptations. We suggested four genes in three QTLs as the candidates contributing to rice NUE during the ecotypic differentiation. In summary, the soil-nitrogen condition drives the adaptive differentiation of NUE between upland and lowland rice independently within the japonica and indica subspecies. These findings can strengthen our understanding of rice adaptation to divergent soil-nitrogen conditions and have implications for the improvement of NUE.

Dietary specialization stands as a major factor in the study of adaptive evolution and the field of conservation biology among animals. Although bats show unparalleled dietary diversification among mammals, specialized carnivory remains relatively rare within this group. Consequently, our comprehension of the genetic and conservation aspects associated with this specific dietary niche in bats has largely remained uncharted. To investigate molecular adaptations and conservation genetics in carnivorous bats, we produced a new draft genome assembly for the carnivorous bat Vampyrum spectrum. Furthermore, we utilized this genome alongside another distantly related carnivorous bat Megaderma lyra, to conduct genome-wide comparative analyses with other bat species. Our findings unveil that genes linked to lipid metabolism exhibit signatures of positive selection and convergent molecular adaptation in the two divergent lineages of carnivorous bats. Intriguingly, we have uncovered that the evolution of dietary specialization in carnivorous bats is accompanied by molecular adaptations acting on genes in the peroxisome proliferator-activated receptors pathways, which are crucial in regulating plasma lipid metabolism and sustaining lipid homeostasis. Additionally, our genomic analyses also reveal low genetic diversity in both carnivorous bat species. This pattern is attributed to their continuously declining population sizes and low levels of heterozygosity, signaling their vulnerability and emphasizing the pressing need for conservation efforts. These genomic discoveries advance our understanding of genetic underpinnings of carnivory in bats and underscore substantial conservation concerns associated with carnivorous bat species.

Gymnurid rays are found in tropical, subtropical, and temperate regions around the world, where they are associated with sandy or muddy bottoms in coastal areas, being easily distinguished from other rays by the width of the disc. In recent years, the systematics of this family have been revised extensively. However, there has been no comprehensive molecular review of the family based on an adequate sample of species and localities, which may have obscured the presence of distinct evolutionary lineages. The present study was based on samples of 12 of the 13 valid species of the genus Gymnura, which were used for a multilocus reconstruction of the evolutionary history of the family Gymnuridae. Our results indicate the existence of several cryptic gymnurid lineages, within the species Gymnura micrura, Gymnura lessae, Gymnura altavela, and Gymnura poecilura. Also, we indicate that only half of the species that compose the genus are known, as well their conservation status. The analyses also indicate that the gymnurids originated during the Paleocene, with events of dispersal and vicariance occurring through the formation of oceanographic barriers, and species diversification peaking during the Oligocene and Miocene. The results of the present study reinforce the need for a comprehensive revision of the systematics of the family, in particular, the widely distributed species that are considered valid taxa, but may, in fact, represent different cryptic species. The inadequate classification of this cryptic diversity may have negative implications for the development of effective conservation measures.

Understanding the driving forces of speciation is a central question in evolutionary biology. Cycas bifida (Dyer) K. D. Hill and Cycas micholitzii Dyer are two morphologically similar Cycas (Cycadaceae) species with deeply pectinate megasporophylls and dichotomously divided leaflets. Geographically, they are isolated by the Red River Fault Zone (RRFZ), which acts as a biogeographical barrier for many Cycas species. In this study, we investigated the divergence, genetic diversity, genetic structure, and demographic history of C. bifida and C. micholitzii to uncover the speciation mechanisms for the two endangered species. Results revealed high historical gene flow but low contemporary gene flow between the two species, with a deep divergence occurring in the Late Miocene. The long-term geographical isolation and ecological niche differentiation were identified as important factors in driving the divergence of the two species, supported by significant isolation by distance testing, barrier analysis, and niche consistency detection. Geographical isolation by the RRFZ played a pivotal role in facilitating their divergence by constraining gene flow. Conservation genetic analyses indicated high genetic diversity within both species, coupled with disparate responses to Pleistocene climate fluctuations: C. micholitzii experienced population expansion, while C. bifida displayed a mild bottleneck effect. To ensure the protection and long-term sustainability of two threatened species, relevant conservation guidelines were proposed based on the assessment of their genetic diversity and structure. This study furnishes valuable insights into the mechanisms underpinning species divergence and delivers actionable recommendations for cycad conservation.

Many examples of phenotypic modifications resulting from high-elevation adaptation have been documented, however, the underlying processes responsible for these modifications and whether the continuity of the adaptation process remain elusive, particularly in plants. The alpine plants distributed along wide elevational gradients provide an ideal system to address this question. Here, we collected transcriptomes from multiple tissues of three species with different elevations (~1500, ~2500, and ~3600 m in the Hengduan Mountains, Southwest China) in two genera Fargesia and Yushania of alpine bamboos, respectively, and conducted evolutionary and expressional analyses. Results showed that high-elevation adaptation emerged earlier in the evolutionary history of both genera and evolved continuously as the elevation increased. Moreover, convergence of genetic changes was observed in the two genera, with amounts of candidate genes responsible for high-elevation adaptation identified under positive selection. Overall, our study provides an empirical example and valuable genetic resource for further investigation of high-elevation adaptation in plants and sheds new light on how plants adapting to high-elevation environments in a biodiversity hotspot.

Evolutionary theory suggests the hypothesis that among genetically isolated populations, phenotypic variation should be smaller in populations with smaller ratios of nonsynonymous to synonymous substitutions (dN/dS) because smaller dN/dS ratios occur under greater purification selections. Two distinct lineages (JPN₁ and JPN₂) of panarctic Daphnia cf. pulex sensu Hebert (1995), invaded independently into Japan from North America, provide an excellent opportunity to test this hypothesis because the earlier invader JPN₁ has a lower dN/dS ratio than JPN₂. Therefore, we examined phenotypic variations in fitness-related traits, including digestive, life-history, and morphological traits, among several genotypes within these two lineages. We found that phenotypic variations were smaller within the JPN₁ lineage than within the JPN₂ lineage. Furthermore, within-lineage variation of the phenotypic plasticity to changing food levels was smaller in the JPN₁ lineage than in the JPN₂ lineage. These results support the hypothesis that the JPN₁ lineage has been more efficiently subjected to negative selection. However, the magnitude of the phenotypic plasticity of these traits was, on average, at the same level between the JPN₁ and JPN₂ lineages and its direction differed among genotypes of these lineages, suggesting that the JPN₂ genotypes might have exploited niches that were different from those of the JPN₁ genotypes.

The adaptive significance of phenotypic differences between females and males can provide insights into sex-specific selection and the evolution of sexual dimorphism. Dioecious plants commonly exhibit sexual dimorphism in height, although its ecological and evolutionary significance have rarely been examined experimentally. Here, we investigate the functional consequences of the temporal reversal of height dimorphism for pollen and seed dispersal in dioecious Rumex hastatulus Baldw., a species in which males are taller than females at flowering and the reverse pattern occurs at fruiting. Populations of this colonizing weed are wind-pollinated and seeds are wind-dispersed. In a glasshouse experiment we manipulated the height of pollen donors and using sex-specific genetic markers compared the paternal success of males of contrasting height and investigated whether seed families showed evidence of sexual dimorphism in early life-history traits. In a second glasshouse experiment using fruiting plants we also examined how female height influenced the distance that seeds were dispersed. We found that taller males had significantly higher siring success than males of equivalent height to flowering females. Similarly, taller females dispersed fruit to greater distances than shorter females. Female seeds were significantly heavier than male seeds and germinated more rapidly, although early seedling growth was greater in males. Our study suggests that the striking sex reversal of height in R. hastatulus likely functions to optimize the contrasting reproductive functions of the sexes by promoting increased pollen and seed dispersal distances. Improved dispersal quality could limit inbreeding and reduce local mate and resource competition within populations.

The genus Impatiens comprises more than 1000 species and displays enormous morphological diversity. As a taxon that is notoriously difficult to classify morphologically, the taxonomic significance of pollen morphology has been discussed in previous studies. However, there was only limited study on the evolution of palynological and macroscopic character in this genus before. In this paper, we observed pollen of 143 species of Impatiens, including all representatives of infrageneric groups and discussed their taxonomic value. Meanwhile, based on the reconstructed phylogenetic framework, we selected five pollen traits, and nine macroscopic traits including both vegetative and reproductive organs for evolutionary analysis. The character reconstruction showed that the morphology and number of aperture, granules in lumina, seed number of per capsule, number of sepals, lateral united petals connate, spur length, and phyllotaxy could be identified as unambiguous, while other characters were ambiguous in the last common ancestor of Impatiens. The results of comprehensively macroscopic characters and palynological evidence suggest that these traits experienced a complicated evolution, exhibit high levels of instability and variability and occur character multiple reversals in the evolutionary processes of Impatiens due to different selection pressures. In addition, we found that there is an evident mosaic evolution in this genus. Pollen and macroscopic character are conserved with a slower evolutionary rate in the I. subgen. Clavicarpa, however, these characters showed higher diversity with a rapid rate of evolution in the I. subgen. Impatiens. Furthermore, the relationship between floral morphology and pollinators was discussed.

Quantifying the relative strength of isolating barriers is a major focus of research on plant speciation. Contrasting life histories and mating systems have the potential to limit gene exchange between closely related populations growing in sympatry. However, few studies have quantified reproductive isolating barriers between conspecific annual and perennial populations and their contributions to total reproductive isolation (RI). Incarvillea sinensis Lam. (Bignoniaceae) is an insect-pollinated herb with largely allopatric annual and perennial populations that differ in mating systems. The perennial populations are primarily outcrossing whereas annual populations are predominantly selfing. At a rare sympatric site in northern China we estimated prezygotic and postzygotic barriers to gene exchange between annual and perennial plants and found complete RI between the two life histories. Annuals exhibited significantly higher ecogeographic isolation than perennials whereas perennials experienced more isolation through pollen–pistil interactions than annuals. Crosses between annuals and perennials demonstrated that postzygotic barriers influencing fruit and seed formation, F₁ germination and survival were negligible for annuals but played a small role for perennials. However, F₁ hybrids of crosses between annuals and perennials produced no pollen and their ovules were largely sterile. Our study provides insight into the relative importance of prezygotic and postzygotic isolating barriers between closely related annual and perennial populations of I. sinensis and some of these barriers could have been involved with speciation. Annuals and perennials of I. sinensis represent two biological species and thus deserve to be recognized as distinct taxonomic species.

Transposable elements (TEs) are prevalent components of diverse genomes, and play an important role on the genomic stability and expression regulation of their adjacent genes. It is interesting to know the variation of TE expression and the effects of the presence/absence of TEs on gene expression after hybridization. Here we assessed the expression variation of TEs and the impacts of TEs on expression of nearby genes after hybridization based on comparisons of three pairs of reciprocal F₁ hybrids and four parents in Capsella rubella. Of the 480 TE families expressed in all the four parents and six F₁ hybrids, 7–23 (1.5%–4.2%) TE families were significantly differentially expressed between in silico and real F₁ hybrids, indicating the expression levels of these TE families were affected during hybridization. In particular, there was a Copia TE superfamily and a non-long terminal repeat (non-LTR) TE differentially expressed between the reciprocal F₁ hybrids of 879 and 86IT1, indicating maternal effects may have impacts on expression of TEs in these F₁ hybrids. Besides the impacts on the expression of TE families of the hybridization, genes adjacent to polymorphic TEs tended to show a higher proportion (24.83%) of allele-specific expression (ASE) in F₁ hybrids. Overall, our results highlight the impacts of hybridization on the expression level variation of TEs, and the effects of TEs on ASE after hybridization.

We represent a comparative analysis of GBSS1 gene fragment sequences for a number of species related to Elymus caninus: Elymus prokudinii, Elymus viridiglumis, Elymus goloskokovii, as well as a number of morphologically deviating biotypes, inhabiting Russia and Kazakhstan. Microevolutionary relationships between species were assessed from dendrograms derived from sequences of exons and introns. In all taxa, the St subgenome was represented by St₂ variants, rather typical of the North American ancestral line of Pseudoroegneria spicata than of the Asian line descending from Pseudoroegneria strigosa. All putative relatives of E. caninus had H₁ subgenome variants linked around the Asian diploid carrier of the H genome from Hordeum jubatum and were divided into two subclades. One of them (H_1-1) contained most of the closely related E. caninus clones, including Elymus uralensis. Another subclade (H_1-2) consisted of five variants phylogenetically related to Elymus mutabilis. We have also studied reproductive relationships between species E. goloskokovii, E. prokudinii, and E. viridiglumis and the degree of their integration into the E. caninus complex. Biotypes included in sexual hybridization formed a single recombination gene pool, within which slight differences in reproductive compatibility were observed. A comprehensive study of microevolutionary differentiation of taxa showed the expediency of taxonomic revision. The species mentioned should probably be relegated to the infraspecific rank within E. caninus s. l.

A fundamental question in speciation genomics is how evolutionary processes shape the genomic landscape of differentiation between species. Regions of elevated differentiation, referred to as genomic islands, could be shared among closely related species (shared islands) or specific to a lineage (lineage-specific islands). Shared islands are typically assumed to result from background selection. However, simulations and empirical studies have suggested that positive selection contributes to both shared and lineage-specific islands. Here, we utilized comparative population genomics to examine the contributions of different evolutionary processes to patterns of genetic differentiation when gene flow and incomplete lineage sorting are minimal. We used whole-genome resequencing data for 135 individuals from four oak species, including two independent species pairs, Quercus variabilis Blume and Quercus acutissima Carruth. in the subgenus Cerris, and Quercus dentata Thunb. and Quercus griffithii Hook.f. & Thomson ex Miq. in the subgenus Quercus. We found that both shared and subgenus-specific islands were caused by positive selection, including selective sweeps in current populations and in their most recent common ancestors. Moreover, the recombination rate was a better predictor of genomic differentiation than gene density. Overall, our results reveal that recombination and positive selection impacted genomic differentiation considerably and provide a more precise grasp of how genomic islands formed in Quercus.