Mimetic seeds attract birds to disperse seeds mainly by mimicking fleshy fruits or arillate seeds, however, they provide little nutritive reward for bird dispersers. The key characteristics of mimetic seeds are conspicuous seed color, hard seed coat, certain toxic secondary metabolites, and perhaps smooth waxy layer. In this review, we discuss the global distribution of mimetic seeds, the interaction of mimetic seeds with bird dispersers, and secondary metabolites that underlie key characteristics of mimetic seeds. Mimetic-seed species mainly occur in the tropics, with large numbers distributed along coastal areas. The interaction between mimetic-seed species and bird dispersers can be antagonistic, mutualistic, or both. These interactions are generally established by conspicuous visual cues and hard tactile cues from mimetic seeds. The formation and variation of key characteristics of mimetic seeds may contribute to the metabolism of several kind of secondary compounds. Here, we also discuss mimetic-seed dispersal in the context of an evolutionary game, and propose several aspects of mimetic-seed dispersal that remain unstudied. While this review is based on preliminary findings and does not account for other potential influencing factors such as climate, it is expected to contribute to an improved understanding of mimetic-seed dispersal.

The genus Salix is a common component of the Northern Hemisphere dendroflora with important ecological and economic value. However, taxonomy and systematics of Salix is extremely difficult and relationships between main lineages, especially deep phylogenies, remain largely unresolved. In this study, we used genome-skimming, plastome assembly, and single-copy orthologs (SCOs) from 66 Salix accessions, along with publicly available plastome and sequence read archive (SRA) datasets to obtain a robust backbone phylogeny of Salix, clarify relationships between its main lineages, and gain a more precise understanding of the origin and diversification of this species-rich genus. The plastome and SCO datasets resolved Salix into two robust clades, with plastome-based phylogenies lacking inner resolution and SCO offering fully resolved phylogenies. Our results support the classification of Salix into five subgenera: Salix, Urbaniana, Triandrae, Longifoliae and Vetrix. We observed a significant acceleration in the diversification rate within the Chamaetia-Vetrix clade, while Salix exhibited increased rates of diversification spanning from the early Oligocene to the late Miocene. These changes coincided with contemporaneous tectonic and climate change events. Our results provide a foundation for future systematic and evolutionary studies of Salix. Additionally, we showed that genome skimming data is an efficient, rapid, and reliable approach for obtaining extensive genomic data for phylogenomic studies, enabling the comprehensive elucidation of Salix relationships.

Species boundaries are dynamic and constantly challenged by gene flow. Understanding the strategies different lineages adopt to maintain ecological and genetic distinctiveness requires employing an integrative species concept that incorporates data from a variety of sources. In this study, we incorporated genetic, ecological, and environmental evidence to assess the extent of speciation or evolutionary divergence within a monophyletic yet dimorphic group (i.e., clade Leucolirion consisting of six species) within the genus Lilium. This clade consists of two lineages that exhibit unexpectedly distinct perianth appearances: whitish trumpet (funnel form, encompassing four species) and orange recurved (reflex form, including two species), respectively, which are separated by completely different pollination syndromes. Transcriptome-based nuclear and plastome datasets indicate that these two lineages are isolated, with only weak ancient gene flow between them. Within each lineage, several taxa with incomplete isolation have diverged, as indicated by weak genetic structure, strong gene flow, and conflicts between nuclear and chloroplast phylogenies, especially in the trumpet lineage. Although these taxa are not entirely independent, our evidence indicates that they are diverging, with recent gene flow disappearing and multiple isolation strategies emerging, such as differences in flowering time and niche specialization. Taken together, our findings suggest that species divergence and maintenance in Lilium are driven by a combination of adaptive and non-adaptive processes, highlighting the complex interplay of historical climate changes, ecological adaptation, and gene flow in shaping biodiversity within this genus.

The black wolfberry (Lycium ruthenicum; 2n = 2x = 24) is an important medicinal plant with ecological and economic value. Its fruits have numerous beneficial pharmacological activities, especially those of anthocyanins, polysaccharides, and alkaloids, and have high nutritional value. However, the lack of available genomic resources for this species has hindered research on its medicinal and evolutionary mechanisms. In this study, we developed the telomere-to-telomere (T2T) nearly gapless genome of L. ruthenicum (2.26 Gb) by integrating PacBio HiFi, Nanopore Ultra-Long, and Hi-C technologies. The assembled genome comprised 12 chromosomes with 37,149 protein-coding genes functionally annotated. Approximately 80% of the repetitive sequences were identified, of which long terminal repeats (LTRs) were the most abundant, accounting for 73.01%. The abundance of LTRs might be the main reason for the larger genome of this species compared to that of other Lycium species. The species-specific genes of L. ruthenicum were related to defense mechanisms, salt tolerance, drought resistance, and oxidative stress, further demonstrating their superior adaptability to arid environments. Based on the assembled genome and fruit transcriptome data, we further constructed an anthocyanin biosynthesis pathway and identified 19 candidate structural genes and seven transcription factors that regulate anthocyanin biosynthesis in the fruit developmental stage of L. ruthenicum, most of which were highly expressed at a later stage in fruit development. Furthermore, 154 potential disease resistance-related nucleotide-binding genes have been identified in the L. ruthenicum genome. The whole-genome and proximal, dispersed, and tandem duplication genes in the L. ruthenicum genome enriched the number of genes involved in anthocyanin synthesis and resistance-related pathways. These results provide an important genetic basis for understanding genome evolution and biosynthesis of pharmacologically active components in the Lycium genus.

Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress, while hexaploid wild Camellia oleifera shows strong freezing tolerance. As a valuable genetic resource of woody oil crop C. oleifera, wild C. oleifera can serve as a case for studying the molecular bases of adaptive evolution to freezing stress. Here, 47 wild C. oleifera from 11 natural distribution sites in China and 4 relative species of C. oleifera were selected for genome sequencing. “Min Temperature of Coldest Month” (BIO6) had the highest comprehensive contribution to wild C. oleifera distribution. The population genetic structure of wild C. oleifera could be divided into two groups: in cold winter (BIO6 ≤ 0 °C) and warm winter (BIO6 > 0 °C) areas. Wild C. oleifera in cold winter areas might have experienced stronger selection pressures and population bottlenecks with lower N_e than those in warm winter areas. 155 single-nucleotide polymorphisms (SNPs) were significantly correlated with the key bioclimatic variables (106 SNPs significantly correlated with BIO6). Twenty key SNPs and 15 key copy number variation regions (CNVRs) were found with genotype differentiation > 50% between the two groups of wild C. oleifera. Key SNPs in cis-regulatory elements might affect the expression of key genes associated with freezing tolerance, and they were also found within a CNVR suggesting interactions between them. Some key CNVRs in the exon regions were closely related to the differentially expressed genes under freezing stress. The findings suggest that rich SNPs and CNVRs in polyploid trees may contribute to the adaptive evolution to freezing stress.

Integrative data from plastid and nuclear loci are increasingly utilized to resolve species boundaries and phylogenetic relationships within major angiosperm clades. Debregeasia (Urticaceae), an economically important genus, presents challenges in species delimitation due to its overlapping morphological traits and unstable taxonomic assignments. Here, we analyzed 14 morphological traits and generated 12 data matrices from the plastomes and nrDNA using genome skimming from the nine recognized morphospecies to clarify species boundaries and assess barcode performance in Debregeasia. We also used a universal set of 353 nuclear genes to explore reticulate evolution and biogeographic history of Debregeasia. Plastomes of Debregeasia exhibited the typical quadripartite structure with conserved gene content and marginal independent variations in the SC/IR boundary at inter- and intra-specific levels. Three Debregeasia species were non-monophyletic and could not be discerned by any barcode; however, ultra-barcodes identified the remaining six (67%), outperforming standard barcodes (56%). Our phylogenetic analyses placed Debregeasia wallichiana outside the genus and suggested six monophyletic clades in Debregeasia, although the placement between Debregeasia hekouensis and Debregeasia libera varied. There was extensive trait overlap in key morphologically diagnostic characters, with reticulation analysis showing potentially pervasive hybridization, likely influenced by speciation patterns and overlaps between species ranges. We inferred that Debregeasia crown diversification began at ca. 12.82 Ma (95% HPD: 11.54-14.63 Ma) in the mid-Miocene within Australia, followed by vicariance and later long-distance dispersal, mainly out of southern China. Our findings highlight the utility of genomic data with integrative lines of evidence to refine species delimitation and explore evolutionary relationships in complex plant lineages.

The utilization of palynological data for plant diversity reconstructions offers notable advantages in addressing the discontinuity of plant fossils in the stratigraphic record. However, additional studies of modern processes are required to validate or refine the accuracy of diversity results obtained from palynological data. In this study, we used a modern pollen dataset of China to compare the accuracy of plant diversity reconstructions using five different palynological diversity indices (i.e., the pollen species number, Berger–Parker index, Simpson diversity index, Hill index, and Shannon–Wiener index) over a large spatial scale. We then identified climate factors that are most strongly correlated with these patterns of plant diversity. We found that the index that most accurately reflects plant diversity is the Shannon–Wiener index. Our analyses indicated that the most effective indices at reflecting plant diversity are the Shannon–Wiener index and Berger–Parker index. Numerical analysis revealed that palynological diversity (measured using the Shannon–Wiener index) was strongly correlated with climatic parameters, in particular average temperature in the coldest month and annual precipitation, suggesting these factors may be primary determinants of plant diversity distribution. We also found that a threshold value of the normalized Shannon–Wiener index (NH = 0.4) approximately aligns with the contour line specifying 400 mm annual precipitation, serving as a rudimentary indicator for assessing plant diversity in arid versus humid climates. This study suggests that pollen diversity indices have remarkable potential for quantitatively reconstructing paleoclimatic parameters.

The future distribution of invading species depends on the climate space available and certain life history traits that facilitate invasion. Here, to predict the spread potential of plant species introduced in North America north of Mexico (NAM), we compiled distribution and life history data (i.e., seed size, life form, and photosynthetic pathways) for 3021 exotic plant species introduced to NAM. We comparatively examined the species’ range size and climate space in both native and exotic regions and the role of key life history traits. We found that large climate space for most exotic plants is still available in NAM. The range sizes in global exotic regions could better predict the current range sizes in NAM than those in global native regions or global native plus exotic regions. C3 species had larger ranges on average than C4 and CAM plants, and herbaceous species consistently showed stronger relationships in range size between native and exotic regions than woody species, as was the case within the C3 species group. Seed size was negatively related to range size both in native regions and in NAM. However, seed size surprisingly showed a positive correlation with global exotic range size and no correlation with the current actual global (native plus exotic) range size. Our findings underline the importance of species’ native distribution and life history traits in predicting the spread of exotic species. Future studies should continue to identify potential climate space and use underappreciated species traits to better predict species invasions under changing climate.

Understanding how and why assemblage dissimilarity changes along spatial gradient is a great challenge in ecology, because answers to these questions depend on the analytical types, dimensions, and components of beta diversity we concerned. To obtain a comprehensive understanding of assemblage dissimilarity and its implications for biodiversity conservation in the Himalayas, we explored the elevational patterns and determinants of beta diversity and its turnover and nestedness components of pairwise and multiple types and taxonomic and phylogenetic dimensions simultaneously. Patterns of beta diversity and their components of different types and dimensions were calculated based on 96 sampling quadrats along an 1800-5400 m elevational gradient. We examined whether and how these patterns differed from random expectations using null models. Furthermore, we used random forest methods to quantify the role of environmental variables representing climate, topography, and human disturbance in determining these patterns. We found that beta diversity and its turnover component, regardless of its types and dimensions, shown a hump-shaped elevational patterns. Both pairwise and multiple phylogenetic beta diversity were remarkably lower than their taxonomic counterpart. These patterns were significantly less than random expectation and were mostly associated with climate variables. In summary, our results suggested that assemblage dissimilarity of seed plants was mostly originate from the replacement of closely related species determined by climate-driven environmental filtering. Accordingly, conservation efforts should better cover elevations with different climate types to maximalize biodiversity conservation, rather than only focus on elevations with highest species richness. Our study demonstrated that comparisons of beta diversity of different types, dimensions, and components could be conductive to consensus on the origin and mechanism of assemblage dissimilarity.

Studies on plant diversity are usually based on the total number of species in a community. However, few studies have examined species richness (SR) of different plant life forms in a community along large-scale environmental gradients. Particularly, the relative importance (RIV) of different plant life forms in a community and how they vary with environmental variables are still unclear. To fill these gaps, we determined plant diversity of ephemeral plants, annual herbs, perennial herbs, and woody plants from 187 sites across drylands in China. The SR patterns of herbaceous plants, especially perennial herbs, and their RIV in plant communities increased with increasing precipitation and soil nutrient content; however, the RIV of annual herbs was not altered along these gradients. The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality. The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments. An obvious shift emerged in plant community composition, SR and their critical impact factors at 238.5 mm of mean annual precipitation (MAP). In mesic regions (> 238.5 mm), herbs were the dominant species, and the SR displayed a relatively slow decreasing rate with increasing aridity, which was mediated mainly by MAP and soil nutrients. In arid regions (< 238.5 mm), woody plants were the dominant species, and the SR displayed a relatively fast decreasing rate with increasing aridity, which was mediated mainly by climate variables, especially precipitation. Our findings highlight the importance of comparative life form studies in community structure and biodiversity, as their responses to gradients differed substantially on a large scale.

Herbaceous plants are an essential component of forest diversity and driver of ecosystem processes. However, because the growth forms and life-history strategies of herbaceous plants differ from those of woody plants, it is unclear whether the mechanisms that drive patterns plant diversity and community structure in these two plant groups are the same. In this study, we determined whether herb and woody plant communities have similar patterns and drivers of alpha- and beta-diversity. We compared species richness, distribution, and abundance of herbs to woody seedlings in a 20-ha Donglingshan warm-temperate forest (Donglingshan FDP), China. We also determined whether variation in patterns of species richness and composition are better explained by environmental or spatial variables. Herbaceous plants accounted for 72% of all species (81 herbaceous, 31 woody) recorded. Alpha- and beta-diversity were higher in herbs than in woody seedlings. Although alpha-diversity of herbs and woody seedlings was not correlated across the site, the local-site contributions to beta-diversity for herbs and woody seedlings were negatively correlated. Habitat type explained slightly more variation in herb community composition than in woody seedling composition, with the highest diversity in the low-elevation slope. Environmental variables explained the variation in species richness and composition more in herbaceous plants than in woody seedlings. Our results indicate that different mechanisms drive variation in the herb and woody seedling communities, with herbs exhibiting greater environmental sensitivity and habitat dependence. These findings contribute to the better understanding of herbaceous plant diversity and composition in forest communities.

Root anatomical traits play an important role in understanding the link between root physiological function and ecological process. To determine how plants change root anatomical traits to adapt to distinct environments, we measured four key root anatomical traits—stele diameter (SD), cortex thickness (CT), root diameter (RD), and the stele to root diameter ratio (SDRD)—of first-order roots of 82 species collected from different vegetation zones along a 2000 m altitudinal gradient on the northern slope of Taibai Mountain. Compared with other altitudes, plants located in temperate birch and fir forests had thinner SD, CT, RD, and SDRD. We found that elevational variation in root anatomical traits could largely be explained by phylogenetic taxonomy (clade). In addition, changes in SD were driven by soil bulk density, whereas variations in CT and RD were influenced by soil available nitrogen. When phylogenetic factors were removed from our analysis, allometric relationships between RD and root anatomical traits (SD and CT) were observed across different altitudes. Our study reveals the influence of phylogeny and environment on the elevational variation in root anatomical traits and further supports the allometric relationship between root anatomical traits (SD and CT) and RD. These findings enhance our understanding of the evolutionary and adaptive mechanisms of root anatomical structures, providing a basis for predicting how root anatomical traits respond to global changes.

The island rule, a general pattern of dwarfism in large species to gigantism in small species on islands relative to mainland, is typically seen as a macroevolutionary phenomenon. However, whether the ecological processes associated with abiotic and biotic factors generate a pattern of plant size variation similar to the island rule remains unknown. We measured plant height for 29,623 individuals of 50 common woody plant species across 43 islands in the Zhoushan Archipelago (8500 years old and yet to undergo major evolutionary adaptation) and the adjacent mainlands in China. We found pronounced variations in plant height, similar to those of the island rule. Interestingly, islands with low resource availability, such as low soil organic matter content and low precipitation, had a high degree of dwarfism; islands experiencing high environmental stress, such as high soil pH, had a high degree of dwarfism; and islands experiencing less plant–plant competition had a high degree of gigantism. The magnitude of plant dwarfism was higher on small and remote islands than on larger and nearer islands. These results highlight the importance of ecological processes associated with abiotic and biotic conditions in shaping the island rule-like patterns of plant size variation. Since our studied archipelago is too young to undergo major evolution, ecological processes likely played a prominent role in generating the observed pattern, challenging the notion that the evolutionary process is the dominant factor underlying the island rule. Future studies on the island rule need to perform experiments to disentangle evolutionary from ecological mechanisms.

The global rise in animal protein consumption has significantly amplified the demand for fodder. A comprehensive understanding of the diversity and characteristics of existing fodder resources is essential for balanced nutritional fodder production. This study investigates the diversity and composition of fodder plants and identifies key species for cattle in Zhaotong City, Yunnan, China, while documenting indigenous knowledge on their usage and selection criteria. Ethnobotanical surveys were conducted in 19 villages across seven townships with 140 informants. Data were collected through semi-structured interviews, free listing, and participatory observation, and analyzed using Relative Frequency Citation. A total of 125 taxa (including 106 wild and 19 cultivated) were reported. The most cited family is Poaceae (27 taxa, 21.43%), followed by Asteraceae (17 taxa, 13.49%), Fabaceae (14 taxa, 11.11%), Polygonaceae (9 taxa, 7.14%) and Lamiaceae (4 taxa, 3.17%). The whole plant (66.04%) and herbaceous plants (84.80%) were the most used parts and life forms. The most cited species were Zea mays, Brassica rapa, Solanum tuberosum, Eragrostis nigra, and Artemisia dubia. Usage of diverse fodder resources reflects local wisdom in managing resource availability and achieving balanced nutrition while coping with environmental and climatic risks. Preferences for certain taxonomic groups are due to their quality as premier fodder resources. To promote integrated crop-livestock farming, we suggest further research into highly preferred fodder species, focusing on nutritional assessment, digestibility, meat quality impacts, and potential as antibiotic alternatives. Establishing germplasm and gene banks for fodder resources is also recommended.

Mating patterns in angiosperms are typically nonrandom, yet the mechanisms driving nonrandom mating remain unclear, especially regarding the effects of quantitative floral traits on plant mating success across male and female functions. In this study, we investigated how variation in spur length and flower number per plant influences mating patterns in Aquilegia rockii within a natural population. Using marker-based paternity analyses and manipulative experiments, we assessed the role of these traits in mating success across both sexual functions. We found significant variation in the mate composition between male and female function, with spur-length frequency positively associated with female outcrossing rate and mate number, but not with male outcrossing or mate number. Most mating events occurred within 10 m, and spur-length frequency positively correlated with mating distance. Regardless of selfing, there was evidence for assortative mating for spur length. Although spur length did not correlate with pollinator visitation, plants with mid-length spurs had higher seed set than those with shorter or longer spurs when autonomous selfing was excluded. Flowers number per plant was only associated with mating distance and female outcrossing rate. Our results suggest that spur length plays a key role in nonrandom mating by frequency-dependent mating, with implications for stabilizing selection and maintenance of genetic diversity. This study advances our understanding of floral diversity by dissecting the role of quantitative floral traits in plant mating through both female and male functions.