Search

Aim: The equator‐to‐poles decline in the number of species, namely the latitudinal diversity gradient (LDG), is the most conspicuous pattern in biology, yet the underlying mechanisms of this pattern remain controversial. Species dispersal could have strong effects on large‐scale species distributions but has rarely been considered in understanding the LDG. Here we sought to examine how dispersal ability may influence the latitudinal phylogenetic patterns of woody angiosperm assemblages. Location: China. Taxon: Woody angiosperms. Methods: Based on a highly supported mega‐phylogeny constructed from plastid genomes, we assessed the patterns of phylogenetic relatedness and dissimilarity of 1184 trees with three different seed dispersal modes (i.e. zoochory, anemochory and autochory) in 12 permanent forest dynamic plots covering tropical, subtropical and temperate zones in China. Results: We found that, compared with zoochorous and anemochorous species, the less vagile autochorous trees exhibited a much weaker latitudinal pattern in phylogenetic relatedness and higher phylogenetic dissimilarity among plots. The phylogenetic dissimilarity pattern of autochorous trees was explained more by geographic distance than environmental factors, consistent with a dominant role for dispersal limitation. Main Conclusions: Our study, for the first time, demonstrates that seed dispersal mode strongly influences the latitudinal phylogenetic patterns of woody angiosperm assemblages in China and highlights the importance of interaction between dispersal limitation and environmental filtering in determining the large‐scale distribution of forest biodiversity. [ABSTRACT FROM AUTHOR]

Soil biota, as legacy effects of previous species in natural ecosystems, profoundly affects plant performance in new habitats and, in turn, plant community. However, how soil biota, as legacy effects of agricultural crops, affects the likelihood of establishment of exotic and native plants in newly abandoned farmland remains poorly understood, which may hinder effective management of agricultural weeds. Here, we grew 58 plant species (28 exotic species and 30 native species) common in Central China in sterilized vs. nonsterilized soils collected from a newly abandoned maize field. We (i) estimated the effects of soil biota on plant shoot, root and total mass, (ii) explored the dependence of soil effects on the plants' phylogenetic distance to maize, origin (native vs. exotic) and life history (annual vs. perennial) and (iii) tested which plant traits could predict soil effects. Soil biota, in general, decreased plant mass, suggesting a dominant role of enemies. The effect of the soil biota on plant total mass was unrelated to the phylogenetic distance of the plants to maize and decreased linearly with increasing plant intrinsic growth ability. Moreover, the soil biota on average had greater negative impacts on the total mass of exotic plants, particularly perennial species, than on that of native plants. Our results suggest that plant intrinsic growth ability, rather than phylogenetic relatedness, is a reliable predictor of soil effects. Additionally, native plants can benefit from plant–soil interactions in competing with exotic perennial plants when initially established in newly abandoned farmlands. [ABSTRACT FROM AUTHOR]

Changes in the amount and timing of precipitation may affect plant species coexistence. However, little is known about how these changes in precipitation structure plant communities. Here, we conducted a 6-year field precipitation manipulation experiment in the semi-arid steppe of Inner Mongolia, China, to assess the importance of species extinction and colonization in community assembly by incorporating information on phylogenetic and functional relatedness. Our results demonstrated that the decline in plant species richness under decreasing precipitation in the late and entire growing season could be attributed to a decrease in species colonization and an increase in species loss, respectively. The increase in species richness under increasing precipitation in the late growing season was mainly caused by increases in colonizing species. The loss of species that were more closely related to other residents under decreasing precipitation in the late growing season did not alter patterns of phylogenetic overdispersion, and the colonization of species that were more distantly related to residents under increasing precipitation in the late growing season shifted functional relatedness from clustering to randomness. Increasing precipitation may weaken the strength of environmental filtering induced by water stress in this semi-arid steppe and thus increase the probability of successful colonization of functionally dissimilar species relative to residents. Our study suggests that incorporating information on the functional and phylogenetic relatedness of locally lost resident species and the colonization of new species into analyses of community assembly processes can provide new insights into the general responses of plant communities to global change. [ABSTRACT FROM AUTHOR]

Aim: We test (1) whether invasive angiosperm (flowering plant) species are a phylogenetically clustered subset of all naturalized angiosperm species within an angiosperm assemblage, (2) whether more harmful invasive species are more strongly, or less strongly, related to each other, (3) whether the result of the first test is consistent with those for geographic regions distributed in substantially different climatic conditions, and (4) whether patterns of phylogenetic relatedness for invasive species in regions across climatic gradients are consistent with those for overall naturalized species. Location: China. Time period: Current. Taxon: Angiosperms (flowering plants). Methods: We recognized 28 province‐level regions in China and collated naturalized and invasive species lists of angiosperms for each region. Two phylogenetic metrics (i.e., net relatedness index and nearest taxon index), which represent different depths of evolutionary history, were used to quantify phylogenetic relatedness of angiosperms in China and in each region. Values of the metrics of phylogenetic relatedness were related to temperature and precipitation. Results: At the national scale, invasive assemblage is a phylogenetically clustered subset of the naturalized species pool. More harmful invasive species are more strongly clustered. At the regional scale, both naturalized and invasive species are phylogenetically clustered subsets of the national naturalized species pool. Furthermore, invasive species in regional floras are also phylogenetically clustered subsets of their respective regional naturalized species pools. Main conclusions Invasive angiosperm species are a phylogenetically clustered subset of naturalized angiosperm species. More harmful invasive species are more strongly clustered with respect to their naturalized species pools, compared to less harmful invasive species. Our findings have significant implications to predicting and controlling invasive species based on phylogenetic relatedness among naturalized species. [ABSTRACT FROM AUTHOR]

The neighborhood effect has become an important framework with which to study the mechanisms that maintain the coexistence of tree species. Phylogenetic relatedness among neighboring plants directly affects species coexistence and the maintenance of tree diversity. And some studies have reported that seedling performance is negatively correlated with phylogenetic relatedness, which termed phylogenetic negative density dependence. Soil-borne fungal pathogens affected seedling performance of phylogenetically related host species, i.e., phylogenetic Janzen-Connell effect. Seedlings may be particularly vulnerable to habitat and neighbor characteristics. Although previous studies have demonstrated the influence of neighborhood effects, phylogenetic relatedness, and habitat filtering on seedling survival, growth, and mortality, the effect of variation in these factors on seedling abundance remains unclear. To address this question, we used a 4-ha (200 m × 200 m) and monitored four-year (2020-2023) seedling dataset from a mid-montane humid evergreen broad-leaved subtropical forest in the Gaoligong Mountains, Yunnan, Southwestern China, and which consisted of 916 seedlings belonging to 56 species. The results of generalized linear mixed models showed no significant effect of conspecific adult neighbors on seedling abundance at any of the intervals evaluated. In contrast, we found evidence of phylogenetic distance density dependence in the forests of the Gaoligong Mountains. Specifically, there was a significant positive effect of the relative average phylogenetic distance between heterospecific adult neighbors and focal seedlings on focal seedling abundance in 2020; however, the relative average phylogenetic distance between heterospecific seedling neighbors and focal seedlings had a significant negative effect on seedling abundance over the four-year period (2020-2023). Among the habitat factors, only light (canopy opening) had a negative effect on seedling abundance in all four years. Light resources may be a limiting factor for seedlings, and determine seedling dynamics in subtropical forests. Overall, our results demonstrated that phylogenetic density dependence and habitat filtering affected subtropical seedling abundance. Our findings provide new evidence of the impact of phylogenetic density dependence on seedling abundance in a subtropical mid-montane humid evergreen broad-leaved forest and highlight the need to incorporate the neighborhood effect, phylogenetic relatedness, and habitat factors in models assessing seedling abundance., (© 2024. The Author(s).)

Background and Aims: Latitudinal diversity gradients have been intimately linked to the tropical niche conservatism hypothesis, which posits that there has been a strong filter due to the challenges faced by ancestral tropical lineages to adapt to low temperatures and colonize extra-tropical regions. In liverworts, species richness is higher towards the tropics, but the centres of diversity of the basal lineages are distributed across extra-tropical regions, pointing to the colonization of tropical regions by phylogenetically clustered assemblages of species of temperate origin. Here, we test this hypothesis through analyses of the relationship between macroclimatic variation and phylogenetic diversity in Chinese liverworts., Methods: Phylogenetic diversity metrics and their standardized effect sizes for liverworts in each of the 28 regional floras at the province level in China were related to latitude and six climate variables using regression analysis. We conducted variation partitioning analyses to determine the relative importance of each group of climatic variables., Key Results: We find that the number of species decreases with latitude, whereas phylogenetic diversity shows the reverse pattern, and that phylogenetic diversity is more strongly correlated with temperature-related variables compared with precipitation-related variables., Conclusions: We interpret the opposite patterns observed in phylogenetic diversity and species richness in terms of a more recent origin of tropical diversity coupled with higher extinctions in temperate regions., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Although campylobacteriosis is a zoonotic foodborne illness, high-risk isolates from animal sources are rarely characterized, and the pathogenic potential of zoonotic strains remains an obstacle to effective intervention against human infection. HS19 has been acknowledged as a maker serotype represented by Campylobacter jejuni (C. jejuni) isolates from patients with post-infection Guillain-Barré syndrome (GBS), which is circulation in developed countries. However, a previous serotype epidemiological study of C. jejuni isolates in an animal population revealed that HS19 was also prevalent in isolates from cattle in China. In this study, to investigate the hazardous potential of zoonotic strains, 14 HS19 isolates from cattle were systematically characterized both by genotype and phenotype. The results showed that all of these cattle isolates belonged to the ST-22 complex, a high-risk lineage represented by 77.2% HS19 clinical isolates from patients worldwide in the PubMLST database, indicating that the ST-22 complex is the prominent clonal complex of HS19 isolates, as well as the possibility of clonal spread of HS19 isolates across different regions and hosts. Nevertheless, these cattle strains clustered closely with the HS19 isolates from patients, suggesting a remarkable phylogenetic relatedness and genomic similarity. Importantly, both tetracycline genes tet(O) and gyrA (T86I) reached a higher proportional representation among the cattle isolates than among the human clinical isolates. A worrying level of multidrug resistance (MDR) was observed in all the cattle isolates, and two MDR profiles of the cattle isolates also existed in human clinical isolates. Notably, although shared with the same serotype HS19 and sequence type ST-22, 35.7% of cattle isolates induced severe gastrointestinal pathology in the IL-10–/– C57BL/6 mice model, indicating that some bacteria could change due to host adaptation to induce a disease epidemic, thus the associated genetic elements deserve further investigation. In this study, HS19 isolates from cattle were first characterized by a systematic evaluation of bacterial genomics and in vitro virulence, which improved our understanding of the potential zoonotic hazard from food animal isolates with high-risk serotypes, and provided critical information for the development of targeted C. jejuni mitigation strategies. [ABSTRACT FROM AUTHOR]

Aim: Previous studies have found strikingly different geographical patterns of phylogenetic diversity of gymnosperms and angiosperms, which have been suggested to result, in part, from the greater age of the former. To assess the effects of clade age on phylogenetic structure, we assessed phylodiversity patterns of pteridophytes (lycophytes and ferns), which combine ancient and modern lineages, across China. Location: China. Time period: Present day. Taxon: Pteridophytes. Methods: We divided China into 66 regions and collated species lists of pteridophytes for each region. We then related taxonomic and phylogenetic diversity, and their related metrics, to six climatic variables for pteridophytes as a whole and for different evolutionary clades. We examined the effect of spatial autocorrelation among regional floras on the results. Results: We found that when all pteridophytes or ferns were considered, the patterns resembled those of gymnosperms, presumably reflecting the effects of several ancient global mass extinctions and the relict distribution of old families. In contrast, when we considered only the modern Polypodiales radiation, which accounts for three‐quarters of current fern diversity and is about as old as the angiosperm radiation, we found a pattern similar to that of angiosperms. This pattern is consistent with the tropical niche conservatism hypothesis and suggests that both major groups of land plants have a broadly similar evolutionary trajectory, with most families originating in tropical conditions and few families adapting to cold and arid conditions. Main conclusions: Our study shows that the phylogenetic structures of more recently evolved and diversified clades of pteridophytes are fairly consistent with the tropical niche conservatism hypothesis, suggesting that the age of the taxon, its physiological adaptations and the global climatic changes that it experienced during its evolutionary history are reflected in the composition of current plant assemblages. [ABSTRACT FROM AUTHOR]

Strong correlations between species diversity and climate have been widely observed, but the mechanism underlying this relationship is unclear. Here, we explored the causes of the richness–climate relationships among passerine birds in China by integrating tropical conservatism and diversification rate hypotheses using path models. We found that assemblages with higher species richness southwest of the Salween–Mekong–Pearl River Divide are phylogenetically overdispersed and have shorter mean root distances (MRDs), while species-rich regions northeast of this divide (e.g. north Hengduan Mountains–south Qinling Mountains) are phylogenetically clustered and have longer MRDs. The results of the path analyses showed that the direct effect of climatic factors on species richness was stronger than their indirect effects on species richness via phylogenetic relatedness, indicating that neither tropical conservatism nor diversification rate hypotheses can well explain the richness–climate relationship among passerines in China. However, when path analyses were conducted within subregions separately, we found that the tropical conservatism hypothesis was well supported in the southwestern Salween–Mekong–Pearl River Divide, while the diversification rate hypothesis could explain the richness–climate relationship well in the northeastern divide. We conclude that the diversity patterns of passerines in different subregions of the Eastern Himalayas-Mountains of Southwest China may be shaped by different evolutionary processes related to geological and climatic histories, which explains why the tropical conservatism or diversification rate hypothesis alone cannot fully explain the richness–climate relationships. [ABSTRACT FROM AUTHOR]

Phaeocystis globosa blooms are recognized as playing an essential role in shaping the structure of the marine community and its functions in marine ecosystems. In this study, we observed variation in the alpha diversity and composition of marine free-living bacteria during P. globosa blooms and identified key microbial community assembly patterns during the blooms. The results showed that the Shannon index was higher before the blooming of P. globosa in the subtropical bay. Marinobacterium (γ-proteobacteria), Erythrobacter (α-proteobacteria), and Persicobacter (Cytophagales) were defined as the most important genera, and they were more correlated with environmental factors at the terminal stage of P. globosa blooms. Furthermore, different community assembly processes were observed. Both the mean nearest relatedness index (NRI) and nearest taxon index (NTI) revealed the dominance of deterministic factors in the non-blooming and blooming periods of P. globosa , while the bacterial communities in marine waters after the blooms tended to be controlled by stochastic factors. Our findings revealed that the assembly of the bacterial community in marine P. globosa blooms is a complex process with mixture effects of marine microbiomes and environmental parameters. [ABSTRACT FROM AUTHOR]

Species assemble into communities through ecological and evolutionary processes. Phylogenetic niche conservatism--the tendency of species to retain ancestral ecological distributions--is thought to influence which species from a regional species pool can persist in a particular environment. We analyzed data for seed plants in China to test hypotheses about the distribution of species within regional floras. Of 16 environmental variables, actual evapotranspiration, minimum temperature of the coldest month, and annual precipitation most strongly influenced regional species richness, phylogenetic dispersion, and phylogenetic diversity for both gymnosperms (cone-bearing plants) and angiosperms (flowering plants). For most evolutionary clades at, and above, the family level, the relationships between metrics of phylogenetic dispersion (i.e., average phylogenetic distance among species), or phylogenetic diversity, and the 3 environmental variables were consistent with the tropical niche conservatism hypothesis, which predicts closer phylogenetic relatedness and reduced phylogenetic diversity with increasing environmental stress. The slopes of the relationships between phylogenetic relatedness and the 3 environmental drivers identified in this analysis were steeper for primarily tropical clades, implying greater niche conservatism, than for primarily temperate clades. These observations suggest that the distributions of seed plants across large-scale environmental gradients in China are constrained by conserved adaptations to the physical environment, i.e., phylogenetic niche conservatism. [ABSTRACT FROM AUTHOR]

Factors that control individual survival dynamics are pivotal determinants of forest diversity. Numerous studies have examined the relative importance of habitat variables and neighborhood effects on individual survival, while few studies have examined this importance in different forest types that largely vary topography. We examined the role of conspecific negative density dependence (CNDD), phylogenetic negative density dependence (PNDD) and habitat variables across life stages in two temperate old-growth forests in Northeast China. Using generalized linear mixed models (GLMMs), we tested whether individual survival is related to neighborhood effects and habitat variables. Our results showed that the relative importance of neighborhood effects and habitat variables to focal individual survival varied among life stages and sites. However, the best-fit models for three life stages (with the exception of seedling stage in the BKPF) at both sites all included habitat variables, indicating that these variables contribute to the patterns of focal individual survival. We found evidence of a CNDD effect, and the strength of this effect decreased as the life stages progressed and varied from a negative effect at the seedling stage to a positive one at the adult stage. This result confirms that the importance of CNDD-based survival at the seedling stage plays a particularly significant role in promoting the coexistence of tree species and maintaining forest diversity. We found evidence of PNDD in our forest, and the impact of heterospecific phylogenetic relatedness on focal individual survival was significantly negative; the strength of PNDD increased as the life stages progressed. The CNDD and PNDD widely varied among species, indicating the importance of including the relative abundance, life history strategies and functional traits of species when determining the factors that affect species sensitivity to neighborhood effects. The results of our study demonstrated that CNDD, PNDD and habitat variables all influence the individual survival of these temperate old-growth forests, but the relative importance of these factors vary among life stages and species. Our results highlight the importance of combining multiple species, life stages, functional traits and large-scale studies for investigating elements that affect species coexistence in tree communities. [ABSTRACT FROM AUTHOR]

Climate change has impacted the distribution and abundance of numerous plant and animal species during the last century. Orchidaceae is one of the largest yet most threatened families of flowering plants. However, how the geographical distribution of orchids will respond to climate change is largely unknown. Habenaria and Calanthe are among the largest terrestrial orchid genera in China and around the world. In this paper, we modeled the potential distribution of eight Habenaria species and ten Calanthe species in China under the near-current period (1970-2000) and the future period (2081-2100) to test the following two hypotheses: 1) narrow-ranged species are more vulnerable to climate change than wide-ranged species; 2) niche overlap between species is positively correlated with their phylogenetic relatedness. Our results showed that most Habenaria species will expand their ranges, although the climatic space at the southern edge will be lost for most Habenaria species. In contrast, most Calanthe species will shrink their ranges dramatically. Contrasting range changes between Habenaria and Calanthe species may be explained by their differences in climate-adaptive traits such as underground storage organs and evergreen/deciduous habits. Habenaria species are predicted to generally shift northwards and to higher elevations in the future, while Calanthe species are predicted to shift westwards and to higher elevations. The mean niche overlap among Calanthe species was higher than that of Habenaria species. No significant relationship between niche overlap and phylogenetic distance was detected for both Habenaria and Calanthe species. Species range changes in the future was also not correlated with their near current range sizes for both Habenaria and Calanthe. The results of this study suggest that the current conservation status of both Habenaria and Calanthe species should be adjusted. Our study highlights the importance of considering climate-adaptive traits in understanding the responses of orchid taxa to future climate change., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Species assemble into communities through ecological and evolutionary processes. Phylogenetic niche conservatism-the tendency of species to retain ancestral ecological distributions-is thought to influence which species from a regional species pool can persist in a particular environment. We analyzed data for seed plants in China to test hypotheses about the distribution of species within regional floras. Of 16 environmental variables, actual evapotranspiration, minimum temperature of the coldest month, and annual precipitation most strongly influenced regional species richness, phylogenetic dispersion, and phylogenetic diversity for both gymnosperms (cone-bearing plants) and angiosperms (flowering plants). For most evolutionary clades at, and above, the family level, the relationships between metrics of phylogenetic dispersion (i.e., average phylogenetic distance among species), or phylogenetic diversity, and the 3 environmental variables were consistent with the tropical niche conservatism hypothesis, which predicts closer phylogenetic relatedness and reduced phylogenetic diversity with increasing environmental stress. The slopes of the relationships between phylogenetic relatedness and the 3 environmental drivers identified in this analysis were steeper for primarily tropical clades, implying greater niche conservatism, than for primarily temperate clades. These observations suggest that the distributions of seed plants across large-scale environmental gradients in China are constrained by conserved adaptations to the physical environment, i.e., phylogenetic niche conservatism., Competing Interests: The authors declare no competing interest.