Population genetics studies of allopolyploid species lag behind those of diploid species because of practical difficulties in analysis of homeologs-duplicated gene copies originating from hybridized parental species. ...Population genetics studies of allopolyploid species lag behind those of diploid species because of practical difficulties in analysis of homeologs-duplicated gene copies originating from hybridized parental species. Pool-Seq, i.e. massive parallel sequencing of pooled individuals, has high potential for detecting nucleotide polymorphisms within and among multiple populations;however, its use has been limited to diploid species. We applied Pool-Seq to an allopolyploid species by developing a bioinformatic pipeline that assigns reads to each homeolog as well as to each polymorphic allele within each homeolog. We simultaneously sequenced eight genes from twenty individuals from each of 24 populations, and found over 100 polymorphic sites in each homeolog. For two sites, we estimated allele frequencies using the number of reads and then validated these estimations by making individual-based estimations. Pool-Seq using our bioinformatic pipeline allows efficient evaluation of nucleotide polymorphisms in a large number of individuals, even in allopolyploid species.展开更多
Aims Litterfall,as an important link between aboveground and belowground processes,plays a key role in forest ecosystems.Here,we test for effects of tree species richness on litter production and litter quality in sub...Aims Litterfall,as an important link between aboveground and belowground processes,plays a key role in forest ecosystems.Here,we test for effects of tree species richness on litter production and litter quality in subtropical forest.The study further encompasses a factorial gradient of secondary succession that resulted from human exploitation.Given that a large percentage of subtropical forests are in secondary successional stages,understanding the role of biodiversity on forest re-growth after disturbance appears critical.Methods From January 2009 to December 2014,we monitored forest litterfall in 27 Comparative Study Plots that spanned a gradient of tree species richness(3-20 species)and secondary successional ages(~20 to 120 years)in Gutianshan Natural Nature Reserve,Zhejiang Province,China.The experiment is part of the biodiversity-ecosystem functioning research platform‘BEF-China’.Tree litterfall was collected in monthly intervals using litter traps.Samples were separated into leaf and non-leaf components.Leaf litter was further sorted into dominant and other species.Community level monthly leaf litter C and N contents were analysed through a full year.General linear mixed-effects models were applied to test for effects of tree species richness and successional age on litter quantity and leaf litter C/N.Important Findings Litterfall increased with species richness among and within successional age and this effect was consistent across years.Successionally older stands had higher litterfall and this effect was related to increased tree species richness.However,species richness did not change the intra-and inter-annual temporal stability of litterfall.Increasing tree species richness increased leaf litter quality(decreased C/N),while successional age had no effect.Our study indicates that more diverse forest stands produce more leaf litter and that this litter has higher N concentrations,which could promote forest growth through accelerated nutrient re-cycling.展开更多
Leaf nitrogen(N) and phosphorus(P) concentrations are critical for photosynthesis, growth, reproduction and other ecological processes of plants. Previous studies on large-scale biogeographic patterns of leaf N and P ...Leaf nitrogen(N) and phosphorus(P) concentrations are critical for photosynthesis, growth, reproduction and other ecological processes of plants. Previous studies on large-scale biogeographic patterns of leaf N and P stoichiometric relationships were mostly conducted using data pooled across taxa, while family/genus-level analyses are rarely reported. Here, we examined global patterns of family-specific leaf N and P stoichiometry using a global data set of 12,716 paired leaf N and P records which includes 204 families, 1,305 genera, and 3,420 species. After determining the minimum size of samples(i.e., 35 records), we analyzed leaf N and P concentrations, N:P ratios and N^P scaling relationships of plants for 62 families with 11,440 records. The numeric values of leaf N and P stoichiometry varied significantly across families and showed diverse trends along gradients of mean annual temperature(MAT) and mean annual precipitation(MAP). The leaf N and P concentrations and N:P ratios of 62 families ranged from 6.11 to 30.30 mg g–1, 0.27 to 2.17 mg g–1, and 10.20 to 35.40, respectively. Approximately 1/3–1/2 of the families(22–35 of 62) showed a decrease in leaf N and P concentrations and N:P ratios with increasing MAT or MAP, while the remainder either did not show a significant trend or presented the opposite pattern. Family-specific leaf N^P scaling exponents did not converge to a certain empirical value, with a range of 0.307–0.991 for 54 out of 62 families which indicated a significant N^P scaling relationship. Our results for the first time revealed large variation in the family-level leaf N and P stoichiometry of global terrestrial plants and that the stoichiometric relationships for at least one-third of the families were not consistent with the global trends reported previously. The numeric values of the family-specific leaf N and P stoichiometry documented in the current study provide critical synthetic parameters for biogeographic modeling and for further studies on the physiological and ecological mechanisms underlying the nutrient use strategies of plants from different phylogenetic taxa.展开更多
Associating with relatives in social groups can bring benefits such as reduced risk of aggression and increased likelihood of cooperation.Competition among relatives over limited resources,on the other hand,can induce...Associating with relatives in social groups can bring benefits such as reduced risk of aggression and increased likelihood of cooperation.Competition among relatives over limited resources,on the other hand,can induce individuals to alter their patterns of association.Population density might further affect the costs and benefits of associating with relatives by altering resource competition or by changing the structure of social groups;preventing easy association with relatives.Consequently,the overlap between genetic and social structure is expected to decrease with increasing population size,as well as during times of increased breeding activity.Here,we use multi-layer network techniques to quantify the similarity between long-term,high resolution genetic,and behavioral data from a large population of free-ranging house mice(Mus musculus domesticus),studied over 10years.We infer how the benefit of associating with genetically similar individuals might fluctuate in relation to breeding behavior and environmental conditions.We found a clear seasonal effect,with decreased overlap between social and genetic structure during summer months,characterized by high temperatures and high breeding activity.Though the effect of overall population size was relatively weak,we found a clear decrease in the overlap between genetic similarity and social associations within larger groups.As well as longer-term within-group changes,these results reveal population-wide short-term shifts in how individuals associate with relatives.Our study suggests that resource competition modifies the trade-off between the costs and benefits of interacting with relatives.展开更多
The pollution of freshwater ecosystems is threatening freshwater plant species diversity worldwide.Freshwater plants,such as the common duckweed(Lemna minor),are potentially sensitive to novel stressful environments.T...The pollution of freshwater ecosystems is threatening freshwater plant species diversity worldwide.Freshwater plants,such as the common duckweed(Lemna minor),are potentially sensitive to novel stressful environments.To test if ecotype diversity could increase resistance to stressful environments,I used seven L.minor populations and measured their growth rates with and without moderate salt stress across an ecotype diversity gradient.The L.minor populations were grown over 5 months in 92 experimental mesocosms,either in ecotype monocultures or in polyculture with either one or three conspecific ecotypes(23 unique compositions).After growing the duckweed in unperturbed conditions(phase 1),the cultures were subjected to moderate salt stress(50 mmol/L NaCl)for several weeks(phase 2).The experiment was conducted in the presence of the natural epimicrobial community associated with the different ecotypes.In phase 2,a subset of these algae added an unintentional second stressor to the experiment.The ecotypes differed in their growth rates,the fastest growing at twice the rate of others.The diversity context further shaped the ecotype growth rates.Ecotype polycultures showed higher abundances towards the end of the experiment,thus over time,as the environment deteriorated,ecotype diversity gained in importance.These findings show that within-species variation in growth rates can translate to a positive effect of ecotype diversity on population abundance.Exposure of L.minor to moderate salt levels did not significantly impact growth rates,although the effect may have been masked by reduced algal stress in the saline environments.展开更多
The traditional view of the genome was once that it is broadly cooperative, with all genes working together amicably to improve the success of the individual as a whole. Benefits to the individual, after all, benefit ...The traditional view of the genome was once that it is broadly cooperative, with all genes working together amicably to improve the success of the individual as a whole. Benefits to the individual, after all, benefit all the component genes, as fair Mendelian inheritance ensures that all the genes and alleles a parent carries are equally likely to be inherited by an offspring. However, more detailed studies of inheritance have shown that this rosy view of cooperation within the genome is untrue. Instead, many genes act selfishly, manipulating gametogenesis to bias transmission in their favor （Butt and Trivers 2006）. This increases their representation in offspring at a cost to the fitness of the individual and the cooperative genes.展开更多
Aims Ecosystem engineers substantially modify the environment via their impact on abiotic conditions and the biota,resulting in facilitation of associated species that would not otherwise grow.Yet,reciprocal effects a...Aims Ecosystem engineers substantially modify the environment via their impact on abiotic conditions and the biota,resulting in facilitation of associated species that would not otherwise grow.Yet,reciprocal effects are poorly understood as studies of plant–plant interactions usually estimate only benefits for associated species,while how another trophic level may mediate direct and indirect feedback effects for ecosystem engineers is hardly considered.Methods We ran a field experiment with two ecosystem engineers(Arenaria tetraquetra and Hormathophylla spinosa)blooming either alone or with associated plants to decompose net effects and to test the hypothesis that pollinator-mediated interactions provide benefits that balance costs of facilitation by ecosystem engineers.Important Findings We found that net costs of facilitation are accompanied by pollinator-mediated benefits.Despite ecosystem engineers producing fewer flowers per plant,they were visited by more and more diverse pollinators per flower when blooming with associated plants than when blooming alone.Although seed production per plant was higher when ecosystem engineers bloomed alone,fruit set and seed set varied between species.In one case(A.tetraquetra),fruit and seed sets were negatively affected by the presence of associated plants,whereas,in another case(H.spinosa),fruit set and seed set were higher and unaffected when ecosystem engineers bloomed with associated plants,respectively.Our findings suggest that besides experiencing direct costs,ecosystem engineers can also benefit from facilitating other species via increasing their own visibility to pollinators.Thus,we highlight that pollination interactions can compensate for costs of facilitation depending on ecosystem engineer species.This study illuminates how the outcome of direct plant–plant interactions might be mediated by indirect interactions including third players.展开更多
Aims Spatial patterns of fungal populations are affected by plant distribu-tion,abiotic factors,fungal dispersal ability and inter-species interac-tions.While several studies have addressed spatial patterns of some my...Aims Spatial patterns of fungal populations are affected by plant distribu-tion,abiotic factors,fungal dispersal ability and inter-species interac-tions.While several studies have addressed spatial patterns of some mycorrhizal,saprotrophic and pathogenic fungi,the method based on fruit-body surveys is not efficient and unreliable to study the spa-tial pattern of root-associated fungal species because most fungi in plant roots do not have sporocarps and cannot be identified based only on morphological traits.Our aims are(i)to determine the spa-tial pattern of common root-associated fungi;(ii)to evaluate whether the abundance and spatial pattern of root-associated fungi and cat-egories of fungi,reflect their biotic and abiotic niche constraints.Methods About 828 soil cores were collected from a 24-ha plot in a sub-tropical forest and Illumina Miseq was carried out to determine fungal composition in root samples and spatial patterns of 1009 common fungal Operational Taxonomic Units(OTUs)were studied using point pattern analyses.Biotic(plant community composition)and abiotic niche constraints on the presence/abundance of a fun-gal OTU was assessed as the n-dimensional niche hypervolumes of biotic and abiotic characteristics.Important Findings Our results showed that(i)most fungal OTUs were highly spa-tially aggregated at small scales(less than 30 m),but that the aggregated pattern decreased,while regular and random patterns increased,with the increasing distance;(ii)A significant positive correlation was found between fungal abundance and aggrega-tion intensity of fungal OTUs,indicating that the dominant fungi tended to be more aggregated in natural forests;(iii)Mean abun-dance and spatial aggregation intensity of ectomycorrhizal and pathogenic fungi were relatively higher than those of saprotrophic fungi,indicating that host plants may play an important role in determining spatial pattern of root-associated fungi;(iv)Spatial patterns of root-associated fungi depended on fungal abundance,fungal functional group,fungal taxa,biotic and abiotic niche hypervolumes of fungal OTUs.展开更多
The monitoring and management of aquatic ecosystems depend on precise estimates of biodiversity.Metabarcoding analyses of environmental nucleic acids(eNAs),including environmental DNA(eDNA)and environmental RNA(eRNA),...The monitoring and management of aquatic ecosystems depend on precise estimates of biodiversity.Metabarcoding analyses of environmental nucleic acids(eNAs),including environmental DNA(eDNA)and environmental RNA(eRNA),have garnered attention for their cost-effective and non-invasive biomonitoring capabilities.However,the accuracy of biodiversity estimates obtained through eNAs can vary among different organismal groups.Here we evaluate the performance of eDNA and eRNA metabarcoding across nine organismal groups,ranging from bacteria to terrestrial vertebrates,in three crosssections of the Yangtze River,China.We observe robust complementarity between eDNA and eRNA data.The relative detectability of eNAs was notably influenced by major taxonomic groups and organismal sizes,with eDNA providing more robust signals for larger organisms.Both eDNA and eRNA exhibited similar cross-sectional and longitudinal patterns.However,the detectability of larger organisms declined in eRNA metabarcoding,possibly due to differential RNA release and decay among different organismal groups or sizes.While underscoring the potential of eDNA and eRNA in large river biomonitoring,we emphasize the need for differential interpretation of eDNA versus eRNA data.This highlights the importance of careful method selection and interpretation in biomonitoring studies.展开更多
Aims Plant diversity has been linked to both increasing and decreasing levels of arthropod herbivore damage in different plant communities.So far,these links have mainly been studied in grasslands or in artificial tre...Aims Plant diversity has been linked to both increasing and decreasing levels of arthropod herbivore damage in different plant communities.So far,these links have mainly been studied in grasslands or in artificial tree plantations with low species richness.Furthermore,most studies provide results from newly established experimental plant communities where trophic links are not fully established or from stands of tree saplings that have not yet developed a canopy.Here,we test how tree diversity in a species-rich subtropical forest in China with fully developed tree canopy affects levels of herbivore damage caused by different arthropod feeding guilds.Methods We established 27 plots of 30×30 m area.The plots were selected randomly but with the constraint that they had to span a large range of tree diversity as required for comparative studies in contrast to sample surveys.We recorded herbivore damage caused by arthropod feeding guilds(leaf chewers,leaf skeletonizers and sap feeders)on canopy leaves of all major tree species.Important Findings Levels of herbivore damage increased with tree species richness and tree phylogenetic diversity.These effects were most pronounced for damage caused by leaf chewers.Although the two diversity measures were highly correlated,we additionally found a significant interaction between them,whereby species richness increased herbivory mostly at low levels of phylogenetic diversity.Tree species with the lowest proportion of canopy leaf biomass in a plot tended to suffer the highest levels of herbivore damage,which is in contrast to expectations based on the resource concentration hypothesis.Our results are in agreement with expectations of the dietary mixing hypothesis where generalist herbivores with a broad spectrum of food plants benefit from increased resource diversity in tree species-rich forest patches.展开更多
Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our o...Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by interspecific and intraspecific trait variation.Methods We measured tree height of 2493 living individuals in 57 plots and specific root length(SRL)on first-order roots of 368 of these individuals across different species richness levels(1,2,4,8 species)in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China(BEF-China)established in 2009.We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity(RaoQ)and further effects of species interactions by variable components of interspecific and intraspecific functional diversity(community weighted trait similarity and trait dissimilarity,CWS and CWD).Finally,we examined the relationships between biodiversity effects on stand-level tree height and functional diversity(RaoQ,CWS and CWD)in SRL using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.Important Findings Our results show that species richness significantly affected SRL in five and tree height in ten out of 16 species.A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in SRL.A positive CE was related to high values of all three components of root functional diversity(RaoQ,CWS and CWD).Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.展开更多
Aims Fine roots play an important role in the biogeochemical cycles of terrestrial ecosystems and are vital for understanding forest ecosystem functioning and services.Higher plant species diversity has been largely r...Aims Fine roots play an important role in the biogeochemical cycles of terrestrial ecosystems and are vital for understanding forest ecosystem functioning and services.Higher plant species diversity has been largely reported to increase aboveground community biomass,but how biodiversity affects fine-root production and the related mechanisms in forests remain unclear.In this study,we aim to answer two questions:(i)does fine-root production increase with tree species richness?(ii)Can this effect be explained by niche complementarity among species?Methods We analyzed data from a large forest biodiversity experiment(BEF-China)with 5-year-old trees.Fine-root growth was measured as standing biomass and annual fine-root regrowth was estimated using ingrowth cores.Moreover,relative yield was calculated to test whether over-or under-yielding occurred when mixtures were compared with the average monoculture of the species included in the mixtures.We calculated functional diversity for fine-root(≤2 mm in diameter)traits by Rao’s quadratic entropy index for each species mixture.The effects of manipulated tree species richness and identity on fine-root traits were analyzed with linear mixed-effects models.Mixed models were also used to test the relationships between tree species richness and fine-root standing biomass,annual regrowth and vertical heterogeneity.Important Findings Fine roots of more than one species were found in half of the soil cores in mixtures indicating that belowground interactions in these young forest stands occurred much earlier than canopy closure.We found significant differences among species in fine-root traits such as diameter and specific root length(SRL),which suggested different resource-use strategies and niche partitioning among species.Mean fine-root diameter of species ranged from 0.31 to 0.74 mm,mean SRL ranged from 12.43 m·g^(−1)to 70.22 m·g^(−1)and mean vertical distribution indexβranged from 0.68 to 0.93.There was a significant positive relationship between species richness and the evenness of the vertical distribution of fine-root standing biomass.Moreover,marginally significant positive relationships existed between species richness and standing biomass as well as annual regrowth of fine roots.Relative yields and Rao’s quadratic entropy index were both not significantly affected by species richness.However,the relative yield of fine-root standing biomass was marginally correlated with Rao’s quadratic entropy index,implying that belowground niche complementarity between species does contribute to diversity effects.In conclusion,our study showed positive effects of species richness on the filling of soil volume by fine roots in the studied experimental forest communities.This has positive effects on fine-root standing biomass and may also lead to increased aboveground biomass.展开更多
Aims Positive plant diversity-ecosystem function relations are ultimately driven by variation in functional traits among individuals that form a community.To date,research has largely focused on the role of species di...Aims Positive plant diversity-ecosystem function relations are ultimately driven by variation in functional traits among individuals that form a community.To date,research has largely focused on the role of species diversity for ecosystem functioning.However,substantial intraspecific trait variation is common and a significant part of this variation caused by genetic differences among individuals.Here,we studied the relative importance of species diversity and seed family(SF)diversity within species for growth and herbivory in experimental subtropical tree assemblages.Methods In 2010,we set up a field experiment in subtropical China,using four species from the local species pool.Trees were raised from seeds,with seeds from the same mother tree forming an SF.We established 23 plots containing one or four species(species diversity treatment)and one or four SFs per species(SF diversity treatment).Tree growth(stem diameter,plant height and crown expansion)and herbivory(percentage leaf loss due to leaf chewers)were monitored annually from 2011 to 2013.Important findings Tree species richness promoted growth but had no effect on herbivory.In contrast,SF diversity reduced growth and increased herbivory but only so in species mixtures.Most of the observed effects were time dependent,with the largest effect found in 2013.Our results suggest that biodiversity can affect plant performance directly via tree species-species interactions,or context dependent,via potential effects on inter-trophic interactions.Two important conclusions should be drawn from our findings.Firstly,in future studies regarding biodiversity and ecosystem functioning(BEF)relationships,intraspecific genetic diversity should be given similar weight as species diversity as it has often been neglected and its effects are not well understood.Secondly,we demonstrate opposite effects of biodiversity among and within species,stressing the importance to consider the effects of multiple levels of biodiversity simultaneously.展开更多
Grassland is one of the largest terrestrial biomes,providing critical ecosystem services such as food production,biodiversity conservation,and climate change mitigation.Global climate change and land-use intensificati...Grassland is one of the largest terrestrial biomes,providing critical ecosystem services such as food production,biodiversity conservation,and climate change mitigation.Global climate change and land-use intensification have been causing grassland degradation and desertification worldwide.As one of the primary medium for ecosystem energy flow and biogeochemical cycling,grassland carbon(C)cycling is the most fundamental process for maintaining ecosystem services.In this review,we first summarize recent advances in our understanding of the mechanisms underpinning spatial and temporal patterns of the grassland C cycle,discuss the importance of grasslands in regulating inter-and intra-annual variations in global C fluxes,and explore the previously unappreciated complexity in abiotic processes controlling the grassland C balance,including soil inorganic C accumulation,photochemical and thermal degradation,and wind erosion.We also discuss how climate and land-use changes could alter the grassland C balance by modifying the water budget,nutrient cycling and additional plant and soil processes.Further,we examine why and how increasing aridity and improper land use may induce significant losses in grassland C stocks.Finally,we identify several priorities for future grassland C research,including improving understanding of abiotic processes in the grassland C cycle,strengthening monitoring of grassland C dynamics by integrating ground inventory,flux monitoring,and modern remote sensing techniques,and selecting appropriate plant species combinations with suitable traits and strong resistance to climate fluctuations,which would help design sustainable grassland restoration strategies in a changing climate.展开更多
In animals, signaling behavior is often context-dependent, with variation in the probability of emitting certain signals dependent on fitness advantages. Senders may adjust signaling rate depending on receiver identit...In animals, signaling behavior is often context-dependent, with variation in the probability of emitting certain signals dependent on fitness advantages. Senders may adjust signaling rate depending on receiver identity, presence of audiences, or noise masking the signal, all of which can affect the benefits and costs of signal production. In the cooperative breeding meerkat Suricata suricatta, group members emit soft contact calls, termed as ＂close calls＂, while foraging in order to maintain group cohesion. Here, we investigated how the close calling rate during foraging was affected by the presence of pups, that produce continuous, noisy begging calls as they follow older group members. Adults decreased their overall close call rate substantially when pups were foraging with the group in comparison to periods when no pups were present. We suggest this decrease was likely due to a masking effect of the loud begging calls, which makes the close call function of maintaining group cohesion partly redundant as the centrally located begging calls can be used in- stead to maintain cohesion. There was some support that adults use close calls strategically to at- tract specific pups based on fitness advantages, that is, as the philopatric sex, females should call more than males and more to female pups than male pups. Dominant females called more than dominant males when a pup was in close proximity, while subordinates showed no sex-based dif- ferences. The sex of the nearest pup did not affect the calling rate of adults. The study shows that meerkats modify their close call production depending on benefits gained from calling and provides an example of the flexible use of one calling system in the presence of another, here contact calls versus begging calls, within the same species.展开更多
Aims Non-structural carbohydrates(NSCs)are plant storage compounds used for metabolism,transport,osmoregulation and regrowth following the loss of plant tissue.Even in conditions suitable for optimal growth,plants con...Aims Non-structural carbohydrates(NSCs)are plant storage compounds used for metabolism,transport,osmoregulation and regrowth following the loss of plant tissue.Even in conditions suitable for optimal growth,plants continue to store NSCs.This storage may be due to passive accumulation from sink-inhibited growth or active reserves that come at the expense of growth.The former pathway implies that NSCs may be a by-product of sink limitation,while the latter suggests a functional role of NSCs for use during poor conditions.Methods Using 13C pulse labelling,we traced the source of soluble sugars in stem and root organs during drought and everwet conditions for seedlings of two tropical tree species that differ in drought tolerance to estimate the relative allocation of NSCs stored prior to drought versus NSCs assimilated during drought.We monitored growth,stomatal conductance,stem water potential and NSC storage to assess a broad carbon response to drought.Important Findings We found that the drought-sensitive species had reduced growth,conserved NSC concentrations in leaf,stem and root organs and had a larger proportion of soluble sugars in stem and root organs that originated from pre-drought storage relative to seedlings in control conditions.In contrast,the drought-tolerant species maintained growth and stem and root NSC concentrations but had reduced leaf NSCs concentrations with a larger proportion of stem and root soluble sugars originated from freshly assimilated photosynthates relative to control seedlings.These results suggest the drought-sensitive species passively accumulated NSCs during water deficit due to growth inhibition,while the drought-tolerant species actively responded to water deficit by allocating NSCs to stem and root organs.These strategies seem correlated with baseline maximum growth rates,which supports previous research suggesting a trade-off between growth and drought tolerance while providing new evidence for the importance of plasticity in NSC allocation during drought.展开更多
Demography determines the strength of genetic drift,which generally reduces genetic variation and the efficacy of selection.Here,we disentangled the importance of demographic processes at a local scale(census size and...Demography determines the strength of genetic drift,which generally reduces genetic variation and the efficacy of selection.Here,we disentangled the importance of demographic processes at a local scale(census size and mating system)and at a species-range scale(old split between population clusters,recolonization after the last glaciation cycle,and admixture)in determining within-population genomic diversity and genomic signatures of positive selection.Analyses were based on re-sequence data from 52 populations of North American Arabidopsis lyrata collected across its entire distribution.The mating system and range dynamics since the last glaciation cycle explained around 60%of the variation in genomic diversity among populations and 52%of the variation in the signature of positive selection.Diversity was lowest in selfing compared with outcrossing populations and in areas further away from glacial refugia.In parallel,reduced positive selectionwas found in selfing populations and in populations with a longer route of postglacial range expansion.The signature of positive selection was also reduced in populations without admixture.We conclude that recent range expansion can have a profound influence on diversity in coding and non-coding DNA,similar in magnitude to the shift toward selfing.Distribution limits may in fact be caused by reduced effective population size and compromised positive selection in recently colonized parts of the range.展开更多
Reviewing the current state of knowledge about sequential extraction applied for soil vanadium （V） fractionation, we identified an urgent requirement of an sequential extraction （SE） specified for V. Namely, almos...Reviewing the current state of knowledge about sequential extraction applied for soil vanadium （V） fractionation, we identified an urgent requirement of an sequential extraction （SE） specified for V. Namely, almost all previous SE extracted only 8.4%-48% of total V in soils （excluding residue）. Thus, we proposed an eight-step SE for V fractionation in soils according to the knowledge gained from literature and our own dissolution experiments with model minerals. After extracting the mobilisable and adsorbed V with de-ionised water and 5 mmol/L phosphate, I moVL pyrophosphate was applied to gather organic matter bound V which minimised the artefact dissolving AI and Fe （hydr）oxides occurred when using HNO3-H202 for extraction. Extraction with 0.4 mol/L NH2OH. HCI was highly selective toward manganese oxides. Fractionation of different crystalline A1 and Fe （hydr）oxides associated V with 1 mol/L HCI, 0.2 mol/L oxalate buffer and 4 mol/L HCI at 95℃especially improved the extractability of V incorporated with crystalline phase associated V. The suitability of our new SE scheme was confirmed by its higher selectivity against the target phases and higher extraction efficiencies （55%-77% of total V） with model minerals and 6 soils of different properties than previous SE.展开更多
Urban environments expose animals to abundant anthropogenic materials and foods that facilitate foraging innovations in species with oppor-tunistic diets and high behavioral flexibility.Neophilia and exploration tende...Urban environments expose animals to abundant anthropogenic materials and foods that facilitate foraging innovations in species with oppor-tunistic diets and high behavioral flexibility.Neophilia and exploration tendency are believed to be important behavioral traits for animals thriving in urban environments.Vervet monkeys(Chlorocebus pygerythrus)are one of few primate species that have successfully adapted to urban environments,thus making them an ideal species to study these traits.Using a within-species cross-habitat approach,we compared neophilia and exploration of novel objects(jointly referred to as"object curiosity")between semi-urban,wild,and captive monkeys to shed light on the cognitive traits facilitating urban living.To measure"object curiosity:"we exposed monkeys to various types of novel stimuli and compared their approaches and explorative behavior.Our results revealed differences in the number of approaches and explorative behavior toward novel stimuli between the habitat types considered.Captive vervet monkeys were significantly more explorative than both semi-urban and wild troops,sug-gesting that positive experiences with humans and lack of predation,rather than exposure to human materials per se,influence object curiosity.Across habitats,juvenile males were the most explorative age-sex class.This is likely due to males being the dispersing sex and juveniles being more motivated to learn about their environment.Additionally,we found that items potentially associated with human food,elicited stronger explorative responses in semi-urban monkeys than non-food related objects,suggesting that their motivation to explore might be driven by"anthrophilia'that is,their experience of rewarding foraging on similar anthropogenic food sources.We conclude that varying levels of exposure to humans,predation and pre-exposure to human food packaging explain variation in"object curiosity"in our sample of vervet monkeys.展开更多
文摘Population genetics studies of allopolyploid species lag behind those of diploid species because of practical difficulties in analysis of homeologs-duplicated gene copies originating from hybridized parental species. Pool-Seq, i.e. massive parallel sequencing of pooled individuals, has high potential for detecting nucleotide polymorphisms within and among multiple populations;however, its use has been limited to diploid species. We applied Pool-Seq to an allopolyploid species by developing a bioinformatic pipeline that assigns reads to each homeolog as well as to each polymorphic allele within each homeolog. We simultaneously sequenced eight genes from twenty individuals from each of 24 populations, and found over 100 polymorphic sites in each homeolog. For two sites, we estimated allele frequencies using the number of reads and then validated these estimations by making individual-based estimations. Pool-Seq using our bioinformatic pipeline allows efficient evaluation of nucleotide polymorphisms in a large number of individuals, even in allopolyploid species.
基金supported by the EU 7th FP Project BACCARA(grant number 226299 to J.-S.H.)the EU 7th FP Project IDPBRIDGE(grant number 608422 to B.S.)+1 种基金the National Basic Research Program of China(grant number 2014CB954004 to J.S.H.)the German Science Foundation(grant FOR-891 to P.A.N.and B.S.).
文摘Aims Litterfall,as an important link between aboveground and belowground processes,plays a key role in forest ecosystems.Here,we test for effects of tree species richness on litter production and litter quality in subtropical forest.The study further encompasses a factorial gradient of secondary succession that resulted from human exploitation.Given that a large percentage of subtropical forests are in secondary successional stages,understanding the role of biodiversity on forest re-growth after disturbance appears critical.Methods From January 2009 to December 2014,we monitored forest litterfall in 27 Comparative Study Plots that spanned a gradient of tree species richness(3-20 species)and secondary successional ages(~20 to 120 years)in Gutianshan Natural Nature Reserve,Zhejiang Province,China.The experiment is part of the biodiversity-ecosystem functioning research platform‘BEF-China’.Tree litterfall was collected in monthly intervals using litter traps.Samples were separated into leaf and non-leaf components.Leaf litter was further sorted into dominant and other species.Community level monthly leaf litter C and N contents were analysed through a full year.General linear mixed-effects models were applied to test for effects of tree species richness and successional age on litter quantity and leaf litter C/N.Important Findings Litterfall increased with species richness among and within successional age and this effect was consistent across years.Successionally older stands had higher litterfall and this effect was related to increased tree species richness.However,species richness did not change the intra-and inter-annual temporal stability of litterfall.Increasing tree species richness increased leaf litter quality(decreased C/N),while successional age had no effect.Our study indicates that more diverse forest stands produce more leaf litter and that this litter has higher N concentrations,which could promote forest growth through accelerated nutrient re-cycling.
基金supported by the National Natural Science Foundation of China (31800397)National Key Research and Development Program of China (2017YFC0503900)+2 种基金the TRY initiative on plant traits (http://www.try-db.org)The TRY database is hosted at the Max Planck Institute for Biogeochemistry (Jena, Germany)supported by DIVERSITAS/Future Earth, the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig and EU project BACI (640176)
文摘Leaf nitrogen(N) and phosphorus(P) concentrations are critical for photosynthesis, growth, reproduction and other ecological processes of plants. Previous studies on large-scale biogeographic patterns of leaf N and P stoichiometric relationships were mostly conducted using data pooled across taxa, while family/genus-level analyses are rarely reported. Here, we examined global patterns of family-specific leaf N and P stoichiometry using a global data set of 12,716 paired leaf N and P records which includes 204 families, 1,305 genera, and 3,420 species. After determining the minimum size of samples(i.e., 35 records), we analyzed leaf N and P concentrations, N:P ratios and N^P scaling relationships of plants for 62 families with 11,440 records. The numeric values of leaf N and P stoichiometry varied significantly across families and showed diverse trends along gradients of mean annual temperature(MAT) and mean annual precipitation(MAP). The leaf N and P concentrations and N:P ratios of 62 families ranged from 6.11 to 30.30 mg g–1, 0.27 to 2.17 mg g–1, and 10.20 to 35.40, respectively. Approximately 1/3–1/2 of the families(22–35 of 62) showed a decrease in leaf N and P concentrations and N:P ratios with increasing MAT or MAP, while the remainder either did not show a significant trend or presented the opposite pattern. Family-specific leaf N^P scaling exponents did not converge to a certain empirical value, with a range of 0.307–0.991 for 54 out of 62 families which indicated a significant N^P scaling relationship. Our results for the first time revealed large variation in the family-level leaf N and P stoichiometry of global terrestrial plants and that the stoichiometric relationships for at least one-third of the families were not consistent with the global trends reported previously. The numeric values of the family-specific leaf N and P stoichiometry documented in the current study provide critical synthetic parameters for biogeographic modeling and for further studies on the physiological and ecological mechanisms underlying the nutrient use strategies of plants from different phylogenetic taxa.
基金Financial support was provided by the Swiss National Science Foundation(31003A_176114 to B.K.,31003A-120444,and 310030M_138389 to A.K.L.)University of Zurich,Promotor foundation,and Claraz Schenkung.
文摘Associating with relatives in social groups can bring benefits such as reduced risk of aggression and increased likelihood of cooperation.Competition among relatives over limited resources,on the other hand,can induce individuals to alter their patterns of association.Population density might further affect the costs and benefits of associating with relatives by altering resource competition or by changing the structure of social groups;preventing easy association with relatives.Consequently,the overlap between genetic and social structure is expected to decrease with increasing population size,as well as during times of increased breeding activity.Here,we use multi-layer network techniques to quantify the similarity between long-term,high resolution genetic,and behavioral data from a large population of free-ranging house mice(Mus musculus domesticus),studied over 10years.We infer how the benefit of associating with genetically similar individuals might fluctuate in relation to breeding behavior and environmental conditions.We found a clear seasonal effect,with decreased overlap between social and genetic structure during summer months,characterized by high temperatures and high breeding activity.Though the effect of overall population size was relatively weak,we found a clear decrease in the overlap between genetic similarity and social associations within larger groups.As well as longer-term within-group changes,these results reveal population-wide short-term shifts in how individuals associate with relatives.Our study suggests that resource competition modifies the trade-off between the costs and benefits of interacting with relatives.
基金the University of Zurich,Switzerland(UZH Forschungskredit)according to the CRediT taxonomy of contributor roles,Owen Petchey contributed in the"Funding Acquisition".
文摘The pollution of freshwater ecosystems is threatening freshwater plant species diversity worldwide.Freshwater plants,such as the common duckweed(Lemna minor),are potentially sensitive to novel stressful environments.To test if ecotype diversity could increase resistance to stressful environments,I used seven L.minor populations and measured their growth rates with and without moderate salt stress across an ecotype diversity gradient.The L.minor populations were grown over 5 months in 92 experimental mesocosms,either in ecotype monocultures or in polyculture with either one or three conspecific ecotypes(23 unique compositions).After growing the duckweed in unperturbed conditions(phase 1),the cultures were subjected to moderate salt stress(50 mmol/L NaCl)for several weeks(phase 2).The experiment was conducted in the presence of the natural epimicrobial community associated with the different ecotypes.In phase 2,a subset of these algae added an unintentional second stressor to the experiment.The ecotypes differed in their growth rates,the fastest growing at twice the rate of others.The diversity context further shaped the ecotype growth rates.Ecotype polycultures showed higher abundances towards the end of the experiment,thus over time,as the environment deteriorated,ecotype diversity gained in importance.These findings show that within-species variation in growth rates can translate to a positive effect of ecotype diversity on population abundance.Exposure of L.minor to moderate salt levels did not significantly impact growth rates,although the effect may have been masked by reduced algal stress in the saline environments.
文摘The traditional view of the genome was once that it is broadly cooperative, with all genes working together amicably to improve the success of the individual as a whole. Benefits to the individual, after all, benefit all the component genes, as fair Mendelian inheritance ensures that all the genes and alleles a parent carries are equally likely to be inherited by an offspring. However, more detailed studies of inheritance have shown that this rosy view of cooperation within the genome is untrue. Instead, many genes act selfishly, manipulating gametogenesis to bias transmission in their favor （Butt and Trivers 2006）. This increases their representation in offspring at a cost to the fitness of the individual and the cooperative genes.
基金supported by the Swiss National Science Foundation[grant numbers 148261,170645 and 180195]by the ETH Biocommunication group.
文摘Aims Ecosystem engineers substantially modify the environment via their impact on abiotic conditions and the biota,resulting in facilitation of associated species that would not otherwise grow.Yet,reciprocal effects are poorly understood as studies of plant–plant interactions usually estimate only benefits for associated species,while how another trophic level may mediate direct and indirect feedback effects for ecosystem engineers is hardly considered.Methods We ran a field experiment with two ecosystem engineers(Arenaria tetraquetra and Hormathophylla spinosa)blooming either alone or with associated plants to decompose net effects and to test the hypothesis that pollinator-mediated interactions provide benefits that balance costs of facilitation by ecosystem engineers.Important Findings We found that net costs of facilitation are accompanied by pollinator-mediated benefits.Despite ecosystem engineers producing fewer flowers per plant,they were visited by more and more diverse pollinators per flower when blooming with associated plants than when blooming alone.Although seed production per plant was higher when ecosystem engineers bloomed alone,fruit set and seed set varied between species.In one case(A.tetraquetra),fruit and seed sets were negatively affected by the presence of associated plants,whereas,in another case(H.spinosa),fruit set and seed set were higher and unaffected when ecosystem engineers bloomed with associated plants,respectively.Our findings suggest that besides experiencing direct costs,ecosystem engineers can also benefit from facilitating other species via increasing their own visibility to pollinators.Thus,we highlight that pollination interactions can compensate for costs of facilitation depending on ecosystem engineer species.This study illuminates how the outcome of direct plant–plant interactions might be mediated by indirect interactions including third players.
基金This study was supported by the National Natural Science Foundation of China(31470565 and 31170495)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDPB0203)National Science and Technology Ministry Major Project(2017YFA0605103).
文摘Aims Spatial patterns of fungal populations are affected by plant distribu-tion,abiotic factors,fungal dispersal ability and inter-species interac-tions.While several studies have addressed spatial patterns of some mycorrhizal,saprotrophic and pathogenic fungi,the method based on fruit-body surveys is not efficient and unreliable to study the spa-tial pattern of root-associated fungal species because most fungi in plant roots do not have sporocarps and cannot be identified based only on morphological traits.Our aims are(i)to determine the spa-tial pattern of common root-associated fungi;(ii)to evaluate whether the abundance and spatial pattern of root-associated fungi and cat-egories of fungi,reflect their biotic and abiotic niche constraints.Methods About 828 soil cores were collected from a 24-ha plot in a sub-tropical forest and Illumina Miseq was carried out to determine fungal composition in root samples and spatial patterns of 1009 common fungal Operational Taxonomic Units(OTUs)were studied using point pattern analyses.Biotic(plant community composition)and abiotic niche constraints on the presence/abundance of a fun-gal OTU was assessed as the n-dimensional niche hypervolumes of biotic and abiotic characteristics.Important Findings Our results showed that(i)most fungal OTUs were highly spa-tially aggregated at small scales(less than 30 m),but that the aggregated pattern decreased,while regular and random patterns increased,with the increasing distance;(ii)A significant positive correlation was found between fungal abundance and aggrega-tion intensity of fungal OTUs,indicating that the dominant fungi tended to be more aggregated in natural forests;(iii)Mean abun-dance and spatial aggregation intensity of ectomycorrhizal and pathogenic fungi were relatively higher than those of saprotrophic fungi,indicating that host plants may play an important role in determining spatial pattern of root-associated fungi;(iv)Spatial patterns of root-associated fungi depended on fungal abundance,fungal functional group,fungal taxa,biotic and abiotic niche hypervolumes of fungal OTUs.
基金the National Key Research and Development Program of China(2022YFC32021001,2021YFC3201003)support.X.Z.was supported by the Fundamental Research Funds for the Central Universities.F.A.was supported by the University of Zurich Research Priority Program“URPP Global Change and Biodiversity”.Y.Z.thanks the China Scholarship Council(CSC NO.202206190065)supporting the visit of the Swiss Federal Institute of Aquatic Science and Technology(Eawag)and the University of Zurich.
文摘The monitoring and management of aquatic ecosystems depend on precise estimates of biodiversity.Metabarcoding analyses of environmental nucleic acids(eNAs),including environmental DNA(eDNA)and environmental RNA(eRNA),have garnered attention for their cost-effective and non-invasive biomonitoring capabilities.However,the accuracy of biodiversity estimates obtained through eNAs can vary among different organismal groups.Here we evaluate the performance of eDNA and eRNA metabarcoding across nine organismal groups,ranging from bacteria to terrestrial vertebrates,in three crosssections of the Yangtze River,China.We observe robust complementarity between eDNA and eRNA data.The relative detectability of eNAs was notably influenced by major taxonomic groups and organismal sizes,with eDNA providing more robust signals for larger organisms.Both eDNA and eRNA exhibited similar cross-sectional and longitudinal patterns.However,the detectability of larger organisms declined in eRNA metabarcoding,possibly due to differential RNA release and decay among different organismal groups or sizes.While underscoring the potential of eDNA and eRNA in large river biomonitoring,we emphasize the need for differential interpretation of eDNA versus eRNA data.This highlights the importance of careful method selection and interpretation in biomonitoring studies.
基金the European project BACCARA funded by the European Commission’s Seventh Framework Program(FP7/2007-2013 under Grant Agreement No.226299)for financial supportthe administration of the Gutianshan National Nature Reserve and to the members of the BEF-China consortium for logistic and intellectual support+1 种基金the National Science Foundation of China(NSFC 30710103907 and 30930005)the German Research Foundation(DFG FOR 891)that granted and permitted the establishment of the experiment.
文摘Aims Plant diversity has been linked to both increasing and decreasing levels of arthropod herbivore damage in different plant communities.So far,these links have mainly been studied in grasslands or in artificial tree plantations with low species richness.Furthermore,most studies provide results from newly established experimental plant communities where trophic links are not fully established or from stands of tree saplings that have not yet developed a canopy.Here,we test how tree diversity in a species-rich subtropical forest in China with fully developed tree canopy affects levels of herbivore damage caused by different arthropod feeding guilds.Methods We established 27 plots of 30×30 m area.The plots were selected randomly but with the constraint that they had to span a large range of tree diversity as required for comparative studies in contrast to sample surveys.We recorded herbivore damage caused by arthropod feeding guilds(leaf chewers,leaf skeletonizers and sap feeders)on canopy leaves of all major tree species.Important Findings Levels of herbivore damage increased with tree species richness and tree phylogenetic diversity.These effects were most pronounced for damage caused by leaf chewers.Although the two diversity measures were highly correlated,we additionally found a significant interaction between them,whereby species richness increased herbivory mostly at low levels of phylogenetic diversity.Tree species with the lowest proportion of canopy leaf biomass in a plot tended to suffer the highest levels of herbivore damage,which is in contrast to expectations based on the resource concentration hypothesis.Our results are in agreement with expectations of the dietary mixing hypothesis where generalist herbivores with a broad spectrum of food plants benefit from increased resource diversity in tree species-rich forest patches.
基金funded by the National Natural Science Foundation of China(No.31300353)China Postdoctoral Science Foundation(No.2014M561089)+4 种基金Science and Technology Planning Project of Jiangxi Provincial Education Department(No.GJJ150384)the entire BEF-China research group for their supportfunded by the German Research Foundation(DFG FOR891)National Natural Science Foundation of China(NSFC)the Swiss National Science Foundation(SNSF).
文摘Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by interspecific and intraspecific trait variation.Methods We measured tree height of 2493 living individuals in 57 plots and specific root length(SRL)on first-order roots of 368 of these individuals across different species richness levels(1,2,4,8 species)in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China(BEF-China)established in 2009.We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity(RaoQ)and further effects of species interactions by variable components of interspecific and intraspecific functional diversity(community weighted trait similarity and trait dissimilarity,CWS and CWD).Finally,we examined the relationships between biodiversity effects on stand-level tree height and functional diversity(RaoQ,CWS and CWD)in SRL using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.Important Findings Our results show that species richness significantly affected SRL in five and tree height in ten out of 16 species.A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in SRL.A positive CE was related to high values of all three components of root functional diversity(RaoQ,CWS and CWD).Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.
基金the general support of the whole BEF-China teamthe Sino-German Centre for Research Promotion in Beijing for travel grants and the participation in a summer school on scientific writing(GZ 785)funded by grants from the National Natural Science Foundation of China(No.31270496 and No.31300353).
文摘Aims Fine roots play an important role in the biogeochemical cycles of terrestrial ecosystems and are vital for understanding forest ecosystem functioning and services.Higher plant species diversity has been largely reported to increase aboveground community biomass,but how biodiversity affects fine-root production and the related mechanisms in forests remain unclear.In this study,we aim to answer two questions:(i)does fine-root production increase with tree species richness?(ii)Can this effect be explained by niche complementarity among species?Methods We analyzed data from a large forest biodiversity experiment(BEF-China)with 5-year-old trees.Fine-root growth was measured as standing biomass and annual fine-root regrowth was estimated using ingrowth cores.Moreover,relative yield was calculated to test whether over-or under-yielding occurred when mixtures were compared with the average monoculture of the species included in the mixtures.We calculated functional diversity for fine-root(≤2 mm in diameter)traits by Rao’s quadratic entropy index for each species mixture.The effects of manipulated tree species richness and identity on fine-root traits were analyzed with linear mixed-effects models.Mixed models were also used to test the relationships between tree species richness and fine-root standing biomass,annual regrowth and vertical heterogeneity.Important Findings Fine roots of more than one species were found in half of the soil cores in mixtures indicating that belowground interactions in these young forest stands occurred much earlier than canopy closure.We found significant differences among species in fine-root traits such as diameter and specific root length(SRL),which suggested different resource-use strategies and niche partitioning among species.Mean fine-root diameter of species ranged from 0.31 to 0.74 mm,mean SRL ranged from 12.43 m·g^(−1)to 70.22 m·g^(−1)and mean vertical distribution indexβranged from 0.68 to 0.93.There was a significant positive relationship between species richness and the evenness of the vertical distribution of fine-root standing biomass.Moreover,marginally significant positive relationships existed between species richness and standing biomass as well as annual regrowth of fine roots.Relative yields and Rao’s quadratic entropy index were both not significantly affected by species richness.However,the relative yield of fine-root standing biomass was marginally correlated with Rao’s quadratic entropy index,implying that belowground niche complementarity between species does contribute to diversity effects.In conclusion,our study showed positive effects of species richness on the filling of soil volume by fine roots in the studied experimental forest communities.This has positive effects on fine-root standing biomass and may also lead to increased aboveground biomass.
基金German Science Foundation(DFG FOR 891/2,Du 404/3-2 to W.D.)is highly acknowledged.
文摘Aims Positive plant diversity-ecosystem function relations are ultimately driven by variation in functional traits among individuals that form a community.To date,research has largely focused on the role of species diversity for ecosystem functioning.However,substantial intraspecific trait variation is common and a significant part of this variation caused by genetic differences among individuals.Here,we studied the relative importance of species diversity and seed family(SF)diversity within species for growth and herbivory in experimental subtropical tree assemblages.Methods In 2010,we set up a field experiment in subtropical China,using four species from the local species pool.Trees were raised from seeds,with seeds from the same mother tree forming an SF.We established 23 plots containing one or four species(species diversity treatment)and one or four SFs per species(SF diversity treatment).Tree growth(stem diameter,plant height and crown expansion)and herbivory(percentage leaf loss due to leaf chewers)were monitored annually from 2011 to 2013.Important findings Tree species richness promoted growth but had no effect on herbivory.In contrast,SF diversity reduced growth and increased herbivory but only so in species mixtures.Most of the observed effects were time dependent,with the largest effect found in 2013.Our results suggest that biodiversity can affect plant performance directly via tree species-species interactions,or context dependent,via potential effects on inter-trophic interactions.Two important conclusions should be drawn from our findings.Firstly,in future studies regarding biodiversity and ecosystem functioning(BEF)relationships,intraspecific genetic diversity should be given similar weight as species diversity as it has often been neglected and its effects are not well understood.Secondly,we demonstrate opposite effects of biodiversity among and within species,stressing the importance to consider the effects of multiple levels of biodiversity simultaneously.
基金supported by the National Natural Science Foundation of China (32125025 and 31988102)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA23080301 and XDA26010303)JMG acknowledges the support of the Israel Science Foundation (1796/19).
文摘Grassland is one of the largest terrestrial biomes,providing critical ecosystem services such as food production,biodiversity conservation,and climate change mitigation.Global climate change and land-use intensification have been causing grassland degradation and desertification worldwide.As one of the primary medium for ecosystem energy flow and biogeochemical cycling,grassland carbon(C)cycling is the most fundamental process for maintaining ecosystem services.In this review,we first summarize recent advances in our understanding of the mechanisms underpinning spatial and temporal patterns of the grassland C cycle,discuss the importance of grasslands in regulating inter-and intra-annual variations in global C fluxes,and explore the previously unappreciated complexity in abiotic processes controlling the grassland C balance,including soil inorganic C accumulation,photochemical and thermal degradation,and wind erosion.We also discuss how climate and land-use changes could alter the grassland C balance by modifying the water budget,nutrient cycling and additional plant and soil processes.Further,we examine why and how increasing aridity and improper land use may induce significant losses in grassland C stocks.Finally,we identify several priorities for future grassland C research,including improving understanding of abiotic processes in the grassland C cycle,strengthening monitoring of grassland C dynamics by integrating ground inventory,flux monitoring,and modern remote sensing techniques,and selecting appropriate plant species combinations with suitable traits and strong resistance to climate fluctuations,which would help design sustainable grassland restoration strategies in a changing climate.
文摘In animals, signaling behavior is often context-dependent, with variation in the probability of emitting certain signals dependent on fitness advantages. Senders may adjust signaling rate depending on receiver identity, presence of audiences, or noise masking the signal, all of which can affect the benefits and costs of signal production. In the cooperative breeding meerkat Suricata suricatta, group members emit soft contact calls, termed as ＂close calls＂, while foraging in order to maintain group cohesion. Here, we investigated how the close calling rate during foraging was affected by the presence of pups, that produce continuous, noisy begging calls as they follow older group members. Adults decreased their overall close call rate substantially when pups were foraging with the group in comparison to periods when no pups were present. We suggest this decrease was likely due to a masking effect of the loud begging calls, which makes the close call function of maintaining group cohesion partly redundant as the centrally located begging calls can be used in- stead to maintain cohesion. There was some support that adults use close calls strategically to at- tract specific pups based on fitness advantages, that is, as the philopatric sex, females should call more than males and more to female pups than male pups. Dominant females called more than dominant males when a pup was in close proximity, while subordinates showed no sex-based dif- ferences. The sex of the nearest pup did not affect the calling rate of adults. The study shows that meerkats modify their close call production depending on benefits gained from calling and provides an example of the flexible use of one calling system in the presence of another, here contact calls versus begging calls, within the same species.
基金supported by the Universität Zürich MSc Ecology Program with additional support by the Universität Zürich Research Priority Program on Global Change and Biodiversity(URPP-GCB).M.O.B.was supported by the Atracción de Talento Investigador Modalidad I Fellowship from the Comunidad de Madrid(grant number 2018-T1/AMB-11095)during the preparation of the manuscript.
文摘Aims Non-structural carbohydrates(NSCs)are plant storage compounds used for metabolism,transport,osmoregulation and regrowth following the loss of plant tissue.Even in conditions suitable for optimal growth,plants continue to store NSCs.This storage may be due to passive accumulation from sink-inhibited growth or active reserves that come at the expense of growth.The former pathway implies that NSCs may be a by-product of sink limitation,while the latter suggests a functional role of NSCs for use during poor conditions.Methods Using 13C pulse labelling,we traced the source of soluble sugars in stem and root organs during drought and everwet conditions for seedlings of two tropical tree species that differ in drought tolerance to estimate the relative allocation of NSCs stored prior to drought versus NSCs assimilated during drought.We monitored growth,stomatal conductance,stem water potential and NSC storage to assess a broad carbon response to drought.Important Findings We found that the drought-sensitive species had reduced growth,conserved NSC concentrations in leaf,stem and root organs and had a larger proportion of soluble sugars in stem and root organs that originated from pre-drought storage relative to seedlings in control conditions.In contrast,the drought-tolerant species maintained growth and stem and root NSC concentrations but had reduced leaf NSCs concentrations with a larger proportion of stem and root soluble sugars originated from freshly assimilated photosynthates relative to control seedlings.These results suggest the drought-sensitive species passively accumulated NSCs during water deficit due to growth inhibition,while the drought-tolerant species actively responded to water deficit by allocating NSCs to stem and root organs.These strategies seem correlated with baseline maximum growth rates,which supports previous research suggesting a trade-off between growth and drought tolerance while providing new evidence for the importance of plasticity in NSC allocation during drought.
基金supported by the Swiss National Science Foundation(PP00P3-123396,PP00P3_146342,31003A_166322)the Fondation Pierre Mercier pour la Science,Lausanne.
文摘Demography determines the strength of genetic drift,which generally reduces genetic variation and the efficacy of selection.Here,we disentangled the importance of demographic processes at a local scale(census size and mating system)and at a species-range scale(old split between population clusters,recolonization after the last glaciation cycle,and admixture)in determining within-population genomic diversity and genomic signatures of positive selection.Analyses were based on re-sequence data from 52 populations of North American Arabidopsis lyrata collected across its entire distribution.The mating system and range dynamics since the last glaciation cycle explained around 60%of the variation in genomic diversity among populations and 52%of the variation in the signature of positive selection.Diversity was lowest in selfing compared with outcrossing populations and in areas further away from glacial refugia.In parallel,reduced positive selectionwas found in selfing populations and in populations with a longer route of postglacial range expansion.The signature of positive selection was also reduced in populations without admixture.We conclude that recent range expansion can have a profound influence on diversity in coding and non-coding DNA,similar in magnitude to the shift toward selfing.Distribution limits may in fact be caused by reduced effective population size and compromised positive selection in recently colonized parts of the range.
基金Gunter Ilgen(University of Bayreuth,Germany)for the support with analysissupported by the China Scholarship Council(No.2011624130)the Swiss National Science Foundation(No.PZ00P2 142232)
文摘Reviewing the current state of knowledge about sequential extraction applied for soil vanadium （V） fractionation, we identified an urgent requirement of an sequential extraction （SE） specified for V. Namely, almost all previous SE extracted only 8.4%-48% of total V in soils （excluding residue）. Thus, we proposed an eight-step SE for V fractionation in soils according to the knowledge gained from literature and our own dissolution experiments with model minerals. After extracting the mobilisable and adsorbed V with de-ionised water and 5 mmol/L phosphate, I moVL pyrophosphate was applied to gather organic matter bound V which minimised the artefact dissolving AI and Fe （hydr）oxides occurred when using HNO3-H202 for extraction. Extraction with 0.4 mol/L NH2OH. HCI was highly selective toward manganese oxides. Fractionation of different crystalline A1 and Fe （hydr）oxides associated V with 1 mol/L HCI, 0.2 mol/L oxalate buffer and 4 mol/L HCI at 95℃especially improved the extractability of V incorporated with crystalline phase associated V. The suitability of our new SE scheme was confirmed by its higher selectivity against the target phases and higher extraction efficiencies （55%-77% of total V） with model minerals and 6 soils of different properties than previous SE.
基金the funding agencies behind this research,the Finnish KONE Foundation,the Wenner Gren Foundation,and the Swiss National Science Foundation(CRSK-3_220769)awarded to SE.
文摘Urban environments expose animals to abundant anthropogenic materials and foods that facilitate foraging innovations in species with oppor-tunistic diets and high behavioral flexibility.Neophilia and exploration tendency are believed to be important behavioral traits for animals thriving in urban environments.Vervet monkeys(Chlorocebus pygerythrus)are one of few primate species that have successfully adapted to urban environments,thus making them an ideal species to study these traits.Using a within-species cross-habitat approach,we compared neophilia and exploration of novel objects(jointly referred to as"object curiosity")between semi-urban,wild,and captive monkeys to shed light on the cognitive traits facilitating urban living.To measure"object curiosity:"we exposed monkeys to various types of novel stimuli and compared their approaches and explorative behavior.Our results revealed differences in the number of approaches and explorative behavior toward novel stimuli between the habitat types considered.Captive vervet monkeys were significantly more explorative than both semi-urban and wild troops,sug-gesting that positive experiences with humans and lack of predation,rather than exposure to human materials per se,influence object curiosity.Across habitats,juvenile males were the most explorative age-sex class.This is likely due to males being the dispersing sex and juveniles being more motivated to learn about their environment.Additionally,we found that items potentially associated with human food,elicited stronger explorative responses in semi-urban monkeys than non-food related objects,suggesting that their motivation to explore might be driven by"anthrophilia'that is,their experience of rewarding foraging on similar anthropogenic food sources.We conclude that varying levels of exposure to humans,predation and pre-exposure to human food packaging explain variation in"object curiosity"in our sample of vervet monkeys.
