查看更多>>摘要：The angiosperm family Elaeagnaceae comprises three genera and ca.100 species distributed mainly in Eurasia and North America.Little family-wide phylogenetic and biogeographic research on Elaeagnaceae has been conducted,limiting the application and preservation of natural genetic resources.Here,we reconstructed a strongly supported phylogenetic framework of Elaeagnaceae to better understand inter-and intrageneric relationships,as well as the origin and biogeographical history of the family.For this purpose,we used both nuclear and plastid sequences from Hyb-Seq and genome skimming approaches to reconstruct a well-supported phylogeny and,along with current distributional data,infer historical biogeographical processes.Our phylogenetic analyses of both nuclear and plastid data strongly support the monophyly of Elaeagnaceae and each of the three genera.Elaeagnus was resolved as sister to the well-supported clade of Hippophae and Shepherdia.The intrageneric relationships of Elaeagnus and Hippophae were also well resolved.High levels of nuclear gene tree conflict and cytonuclear discordance were detected within Elaeagnus,and our analyses suggest putative ancient and recent hybridization.We inferred that Elaeagnaceae originated at ca.90.48 Ma(95％CI=89.91-91.05 Ma),and long-distance dispersal likely played a major role in shaping its intercontinentally disjunct distribution.This work presents the most comprehensive phylogenetic framework for Elaeagnaceae to date,offers new insights into previously unresolved relationships in Elaeagnus,and provides a foundation for further studies on classification,evolution,biogeography,and conservation of Elaeagnaceae.
查看更多>>摘要：The Indo-Burma Biodiversity Hotspot is renowned for its rich biodiversity,including that of vascular plants.However,the fern diversity and its endemism in this hotspot have not been well understood and so far,the diversity of very few groups of ferns in this region has been explored using combined mo-lecular and morphological approaches.Here,we updated the plastid phylogeny of the Java fern genus Leptochilus with 226(115％increase of the latest sampling)samples across the distribution range,spe-cifically those of three phylogenetically significant species,Leptochilus ovatus,L.pedunculatus,and L.pothifolius.We also reconstructed the first nuclear phylogeny of the genus based on pgiC gene data.Based on molecular and morphological evidence,we identified three new major clades and six new subclades,redefined three existing species,discovered a number of cryptic species of the genus,and elucidated the evolution of the three most variable characters.Our divergence time analyses and ancestral area reconstruction showed that Leptochilus originated in the Oligocene and diversified from early Miocene and 15 dispersal events from lower to higher latitudes are identified.The evolution of three most important morphological characters is analyzed in a context of the new phylogeny.Our analysis showed that 30(59％of total 51)species of Leptochilus occur in Indo-Burma hotspot,24(80％of the 30 species)of which are endemic to this hotspot.We argue that the Indo-Burma hotspot should be recognized as a diversity hotspot for ferns.
查看更多>>摘要：Genome skimming has dramatically extended DNA barcoding from short DNA fragments to next gen-eration barcodes in plants.However,conserved DNA barcoding markers,including complete plastid genome and nuclear ribosomal DNA(nrDNA)sequences,are inadequate for accurate species identifi-cation.Skmer,a recently proposed approach that estimates genetic distances among species based on unassembled genome skims,has been proposed to effectively improve species discrimination rate.In this study,we used Skmer to identify species based on genomic skims of 47 individuals representing 10 out of 13 species of Schima(Theaceae)from China.The unassembled reads identified six species,with a species identification rate of 60％,twice as high as previous efforts that used plastid genomes(27.27％).In addition,Skmer was able to identify Schima species with only 0.5 × sequencing depth,as six species were well-supported with unassembled data sizes as small as 0.5 Gb.These findings demonstrate the potential for Skmer approach in species identification,where nuclear genomic data plays a crucial role.For taxonomically difficult taxa such as Schima,which have diverged recently and have low levels of genetic variation,Skmer is a promising alternative to next generation barcodes.
查看更多>>摘要：Phylogenetic niche conservatism posits that species tend to retain ancestral ecological traits and dis-tributions,which has been broadly tested for lineages originating in tropical climates but has been rarely tested for lineages that originated and diversified in temperate climates.Liverworts are thought to originate in temperate climates.Mean lineage age reflects evolutionary history of biological commu-nities.Here,using regional liverwort floras across a long latitudinal gradient from tropical to arctic cli-mates in North America,we test the age-component of the temperate niche conservatism hypothesis.Mean genus age(MGA)was estimated for each of 76 regional floras of liverworts.We related MGA to climatic variables for North America as a whole and for its eastern and western parts separately,and used variation partitioning analysis to assess the relative importance of temperature-versus precipitation-related variables and of climate extremes versus seasonality on MGA.We found that older genera of liverworts tend to concentrate in humid regions of intermediate temperatures in the range of 10 ℃-20 ℃,from which liverworts have adapted to and diversified into more arid,colder,and hotter regions,supporting the temperate niche conservatism hypothesis.We also found that across North America the MGA of liverwort assemblages is more strongly affected by precipitation-related variables than by temperature-related variables,and is more strongly affected by climate extremes than by climate sea-sonality.Geographic patterns of the MGA of liverworts are consistent with the temperate niche conservatism hypothesis,rather than the tropical niche conservatism hypothesis,the latter of which is broadly supported by angiosperms.
José Luiz Alves SilvaAlexandre SouzaAngela Pierre Vitória
732-743页
查看更多>>摘要：Functional diversity(FD)reflects within-and between-site variation of species traits(α-and β-FD,respectively).Understanding how much data types(occurrence-based vs.abundance-weighted)and spatial scales(sites vs.regions)change FD and ultimately interfere with the detection of underlying geoclimatic filters is still debated.To contribute to this debate,we explored the occurrence of 1690 species in 690 sites,abundances of 1198 species in 343 sites,and seven functional traits of the Atlantic Forest woody flora in South America.All FD indices were sensitive and dependent on the data type at both scales,with occurrence particularly increasing α richness and dispersion(occurrence＞abundance in 80％of the sites)while abundance increased β total,β replacement,and α evenness(abundance＞occurrence in 60％of the sites).Furthermore,detecting the effect of geoclimatic filters depended on the data type and was scale-dependent.At the site scale,precipitation seasonality and soil depth had weak effects on α-and β-FD(max.R2=0.11).However,regional-scale patterns of α richness,dispersion,and evenness strongly mirrored the variation in precipitation seasonality,soil depth,forest stability over the last 120 kyr,and cation exchange capacity(correlations＞0.80),suggesting that geo-climatic filters manifest stronger effects at the regional scale.Also,the role of edaphic gradients expands the idea of biogeographical filters beyond climate.Our findings caution functional biogeographic studies to consider the effect of data type and spatial scale before designing and reaching ecological conclusions about the complex nature of FD.
查看更多>>摘要：Grasslands account for about a quarter of the Earth's land area and are one of the major terrestrial ecosystems,with significant ecological and economic values.The influence of environmental factors and management types on grassland biodiversity has garnered considerable attention.This study investi-gated how patterns of species richness are influenced by geographical distance,environmental gradients,and management type in the moist mountain grasslands of northeastern Yunnan,China.We used structural equation modeling to disentangle the impacts of environment and management on phylo-genetic community structure,and using partial Mantel tests estimated the roles of dispersal limitation and environmental filtering on taxonomic and phylogenetic beta diversity of three types of grasslands.Our results show that taxonomic alpha diversity increased in grazed grasslands and decreased in mowed grasslands,compared with protected grasslands.However,the phylogenetic structure of both grazed and mowed grassland communities was clustered,whereas that of protected communities was random.Moreover,both grazing and mowing significantly reduced the taxonomic and phylogenetic beta diversity of grasslands,with the lowest values observed in mowed grasslands.Both taxonomic and phylogenetic beta diversity were dominated by species turnover under different management types.The taxonomic and phylogenetic beta diversities of protected and grazed grasslands were simultaneously affected by environmental filtering and dispersal limitation,with the later playing a stronger role.In addition,mowing and following management measures had a stronger filtering effect on grassland community structure,as reflected by changes in community composition.
查看更多>>摘要：As the core of leaf functional traits,the trade-off relationship between the petiole and lamina expresses the plant's adaptability to the environment in terms of support structure and photosynthesis.We investigated the proportions of allometric growth in the relationship between the petiole and the lamina of broadleaf woody plants in temperate highland Tianshan Mountains montane forests through three dimensions(length,area,and mass),including the length of the lamina(LL)and the length of the petiole(PL),and the area of the lamina(LA)and petiole cross sectional area(PCA)versus the mass of the lamina(LM)and the mass of the petiole(PM),as well as exploring the characteristics of the variance in response to seasonal changes.We found that the functional traits in all three dimensions showed a clear convergent evolution as the seasons progressed,that is,a"seasonal effect"of increasing and then decreasing.The effect of the petiole-lamina relationship under spring was minimal in the area dimension;the effects of the three-dimensional relationships of the traits were all highest in summer,and the effect of the petiole-lamina relationship was lower in autumn.We also found that petiole traits are simultaneously and multiply affected by lamina traits,with LA and LM having additional effects on the length/mass and area dimensions,respectively.Compared to tree species,shrub species significantly require more light intensity and support capacity.Compound-leaved plants would invest more in pho-toluminescence,increasing leaf light capture efficiency and static load and dynamic resistance.Our re-sults suggest that plants have rather complex trade-off mechanisms at the leaf level influencing their ability to adapt to the environment,emphasize the need for leaf-level studies on the relationships be-tween functional traits in plants,and illustrate the importance of the season as a distinct time scale for plant trade-off mechanisms.
查看更多>>摘要：Descriptions of floral traits based on the visual capabilities of pollinators would advance our under-standing of flower evolution and plant-pollinator relationships.One such trait is the contrasting UV bullseye color pattern,which is invisible to human eyes but can be perceived by bee pollinators.How-ever,it remains largely unknown how UV bullseye size affects male and female reproductive fitness.We examined UV bullseye patterns in the dioecious Herpetospermum pedunculosum,and quantified the ef-fects of UV bullseye size on male and female fitness.Both UV bullseye size and flower size were larger in male flowers than in female flowers.The dominant pollinators of H.pedunculosum were bees,which could perceive the UV bullseye pattern.Bee pollinators exhibited a preference for male flowers with nectar rewards,and visited a greater number of male flowers on plants with a larger UV bullseye.Male reproductive fitness was found to decrease in plants with larger UV bullseyes,likely due to the high rate of intra-plant pollen transfer.Rewardless female flowers were less attractive to bee pollinators,resulting in pollen limitation of seed production.Female flowers with moderate UV bullseye size produced more seeds.Our results suggest that UV bullseye is subject to different selection via male and female fitness of H.pedunculosum with deceptive pollination,and large UV bullseye is generally not favored.This research is the first to examine the relationship between UV bullseye size and plant reproductive success,high-lighting that floral evolution should be investigated from the pollinator's eye in future research.
查看更多>>摘要：Flowering phenology of plants,which is important for reproductive growth,has been shown to be influenced by climate change.Understanding how flowering phenology responds to climate change and exploring the variation of this response across plant groups can help predict structural and functional changes in plant communities in response to ongoing climate change.Here,we used long-term collec-tions of 33 flowering plant species from the Gongga Mountains(Mt.Gongga hereafter),a biodiversity hotspot,to investigate how plant flowering phenology changed over the past 70 years in response to climate change.We found that mean flowering times in Mt.Gongga were delayed in all vegetation types and elevations over the last 70 years.Furthermore,flowering time was delayed more in lowlands than at high elevations.Interestingly,we observed that spring-flowering plants show earlier flowering times whereas summer/autumn plants show delayed flowering times.Non-synchronous flowering phenology across species was mainly driven by changes in temperature and precipitation.We also found that the flowering phenology of 78.8％plant species was delayed in response to warming temperatures.Our findings also indicate that the magnitude and direction of variation in plant flowering times vary significantly among species along elevation gradients.Shifts in flowering time might cause trophic mismatches with co-occurring and related species,affecting both forest ecosystem structure and function.
查看更多>>摘要：Andromonoecy is a rare sexual system in plants.The function of additional male flowers in andromo-noecious species has been widely discussed;however,few studies have taken offspring fitness into ac-count.In addition,little is known about the mechanisms that maintain andromonoecy in autogamous species.In this study,we compared morphology,pollinator preference,pollen production and export,siring ability,natural siring success,hundred seed dry weight,and seed germination rates between male and hermaphroditic flowers in an endangered autogamous andromonoecious species,Sagittaria guaya-nensis.Male flowers,which are larger than hermaphroditic flowers,required fewer resources to produce.Pollinators visited male flowers more frequently than they visited hermaphroditic flowers.In addition,pollen production and export were higher in male flowers.Hand pollination demonstrated that siring ability did not differ between flower type.However,the natural siring success of male flowers was triple that of hermaphroditic flowers.The seeds sired by male flowers performed better than those sired by hermaphroditic flowers,with greater dry weight and higher germination rate.In conclusion,male flowers may be superior pollen donors for outcrossing.The maintenance of andromonoecy in S.guayanensis may result from the better performance of male flowers in male function compared to that of hermaphroditic flowers.
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