ABSTRACT
The shifts of bird song frequencies in urbanized areas provide a unique system to understand avian acoustic responses to urbanization. Using passive acoustic monitoring and automatic bird sound recognition technology, we explored the frequency variations of six common urban bird species and their associations with habitat structures. Our results demonstrated that bird song frequencies in urban areas were significantly higher than those in peri-urban and rural areas. Anthropogenic noise and habitat structure were identified as crucial factors shaping the acoustic space for birds. We found that noise, urbanization, and open understory spaces are factors contributing to the increase in the dominant frequency of bird sounds. However, habitat variables such as vegetation density and tree height can potentially slow down this upward trend. These findings offer essential insights into the behavioral response of birds in a variety of urban forest habitats, with implications for urban ecosystem management and habitat restoration.
ABSTRACT
Background: The evolution of heterostyly, a genetically controlled floral polymorphism, has been a hotspot of research since the 19th century. In recent years, studies on the molecular mechanism of distyly (the most common form of heterostyly) revealed an evolutionary convergence in genes for brassinosteroids (BR) degradation in different angiosperm groups. This floral polymorphism often exhibits considerable variability that some taxa have significant stylar dimorphism, but anther height differs less. This phenomenon has been termed "anomalous" distyly, which is usually regarded as a transitional stage in evolution. Compared to "typical" distyly, the genetic regulation of "anomalous" distyly is almost unknown, leaving a big gap in our understanding of this special floral adaptation strategy. Methods: Here we performed the first molecular-level study focusing on this floral polymorphism in Guettarda speciosa (Rubiaceae), a tropical tree with "anomalous" distyly. Comprehensive transcriptomic profiling was conducted to examine which genes and metabolic pathways were involved in the genetic control of style dimorphism and if they exhibit similar convergence with "typical" distylous species. Results: "Brassinosteroid homeostasis" and "plant hormone signal transduction" was the most significantly enriched GO term and KEGG pathway in the comparisons between L- and S-morph styles, respectively. Interestingly, homologs of all the reported S-locus genes either showed very similar expressions between L- and S-morph styles or no hits were found in G. speciosa. BKI1, a negative regulator of brassinosteroid signaling directly repressing BRI1 signal transduction, was identified as a potential gene regulating style length, which significantly up-regulated in the styles of S-morph. Discussion: These findings supported the hypothesis that style length in G. speciosa was regulated through a BR-related signaling network in which BKI1 may be one key gene. Our data suggested, in species with "anomalous" distyly, style length was regulated by gene differential expressions, instead of the "hemizygous" S-locus genes in "typical" distylous flowers such as Primula and Gelsemium, representing an "intermediate" stage in the evolution of distyly. Genome-level analysis and functional studies in more species with "typical" and "anomalous" distyly would further decipher this "most complex marriage arrangement" in angiosperms and improve our knowledge of floral evolution.
ABSTRACT
KEY MESSAGE: This study identified candidate genes related to fruit yield for an emerging medicinal crop, weeping forsythia. BACKGROUND: The genetic basis of crop yield is an agricultural research hotspot. Identifying the genes related to yield traits is the key to increase the yield. Weeping forsythia is an emerging medicinal crop that currently lacks excellent varieties. The genes related to fruit yield in weeping forsythia have not been identified. OBJECTIVE: Thus, we aimed to screen the candidate genes related to fruit yield of weeping forsythia by using genome-wide association analysis. METHODS: Here, 60 samples from the same field and source of weeping forsythia were collected to identify its yield-related candidate genes. Association analysis was performed on the variant loci and the traits related to yield, i.e., fruit length, width, thickness, and weight. RESULTS: Results from admixture, neighbor-joining, and kinship matrix analyses supported the non-significant genetic differentiation of these samples. Significant association was found between 2 variant loci and fruit length, 8 loci and fruit width, 24 loci and fruit thickness, and 13 loci and fruit weight. Further search on the 20 kb up/downstream of these variant loci revealed 1 gene related to fruit length, 16 genes related to fruit width, 12 genes related to fruit thickness, and 13 genes related to fruit weight. Among which, 4 genes, namely, WRKY transcription factor 35, salicylic acid-binding protein, auxin response factor 6, and alpha-mannosidase were highly related to the fruit development of weeping forsythia. CONCLUSION: This study identify four candidate genes related to fruit development, which will provide useful information for the subsequent molecular-assisted and genetic breeding of weeping forsythia.
Subject(s)
Forsythia , Forsythia/genetics , Fruit/genetics , Genome-Wide Association Study , Phenotype , Plant BreedingABSTRACT
Little is known about the distribution and bioaccumulation of organophosphate esters (OPEs) in mangrove ecosystems. In this study, water, sediments, plants and animals were collected from Qi'ao Island Mangrove Nature Reserve to investigate the levels, bioaccumulation and biomagnification of OPEs. Concentrations of ΣOPEs in the mangrove plant Sonneratia apetala (an exotic species) were greater than those in Kandelia obovata (a native species). Translocation factors of OPEs in the two mangrove tree species were greater than 1, indicating that OPEs were mainly absorbed in aboveground tissues. Concentrations of OPEs in mangrove trees and animals were negatively correlated with their log Kow, suggesting that accumulation of OPEs in mangrove biota was influenced by hydrophobicity. A significant difference for concentrations of ΣOPEs was found among the eight mangrove animal species. Concentrations of ΣOPEs in mangrove animals were related with lipid contents, feeding habits and Kow of OPEs. Biota-sediment accumulation factor of OPEs was larger than 1, suggesting that bioaccumulation of OPEs occurred in mangrove animals. The targeted OPEs except isodecyl diphenyl phosphate were not biomagnified in mangrove animals. This study highlights bioaccumulation of OPEs in mangrove biota and suggests further concern about the ecological risk of OPEs to mangrove biota.
Subject(s)
Estuaries , Water Pollutants, Chemical , Animals , Bioaccumulation , China , Ecosystem , Environmental Monitoring , Esters , Organophosphates , Rivers , Water Pollutants, Chemical/analysisABSTRACT
BACKGROUND: Understanding the genetic mechanisms of local adaptation is an important emerging topic in molecular ecology and evolutionary biology. RESULTS: Here, we identify the physiological changes and differential expression of genes among different weeping forsythia populations under drought stress in common garden experiments. Physiological results showed that HBWZ might have higher drought tolerance among four populations. RNA-seq results showed that significant differential expression in the genes responding to the synthesis of flavonoids, aromatic substances, aromatic amino acids, oxidation-reduction process, and transmembrane transport occured among four populations. By further reanalysis of results of previous studies, sequence differentiation was found in the genes related to the synthesis of aromatic substances among different weeping forsythia populations. CONCLUSIONS: Overall, our study supports the hypothesis that the dual differentiation in gene efficiency and expression increases among populations in response to heterogeneous environments and is an important evolutionary process of local adaptation. Here, we proposed a new working model of local adaptation of weeping forsythia populations under different intensities of drought stress, which provides new insights for understanding the genetic mechanisms of local adaptation for non-model species.
Subject(s)
Acclimatization/genetics , Droughts , Forsythia/genetics , Gene Expression Regulation, Plant , Forsythia/physiology , RNA, Plant , RNA-Seq , Real-Time Polymerase Chain Reaction , Stress, Physiological , TranscriptomeABSTRACT
The pollination syndrome concept has provided powerful utility in understanding the evolution and adaptation of floral traits. However, the utility of this conception has been questioned on the grounds that flowers usually attract a broader spectrum of visitors than one might expect. Furthermore, the relationship between plant specialization and floral traits is poorly understood. Here, we examined the applicability of using the pollination syndrome to predict the pollinators of plants on Yongxing Island. We used the species-level specialization of pollination networks to compare the difference of plant ecological specialization among floral traits. The result of full model was not significant, indicating that floral traits did not affect the pollinator functional groups. The five floral traits explained only 22.5% of the pollinator's visitation preference. Our results showed that plants were visited by more pollinator species than pollination syndromes predicted. Plants with restrictive flowers showed higher specialization than those with unrestrictive flowers, while other floral traits exhibited no significant effect on plant specialization. Generalized pollination system on oceanic island might influence the predictive accuracy of pollination syndromes and the relationship between floral traits and plant ecological specialization. Our findings highlighted the utility and limitations of pollination syndromes concept in oceanic island communities.
Subject(s)
Ecological and Environmental Phenomena/physiology , Insecta/metabolism , Pollination/physiology , Animals , China , Ecology , Flowers , Islands , Plants , Species SpecificityABSTRACT
Halogenated flame retardants (HFRs) are ubiquitous in the environment, but little information is available about the bioaccumulation of HFRs in mangrove plants. In this study, three mangrove plant species were collected from Futian National Nature Reserve of Shenzhen City, South China to investigate the bioaccumulation of polybrominated diphenyl ethers (PBDEs) and several alternative halogenated flame retardants (AHFRs), including decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), hexabromobenzene (HBB), pentabromotoluene (PBT), tetrabromop-xylene (pTBX), pentabromoethylbenzene (PBEB) and dechlorane plus (DP). The mean concentrations of PBDEs, DBDPE, BTBPE, pTBX, PBT, PBEB, HBB and DP in mangrove plant species were 2010, 1870, 36.2, 18.7, 40.1, 17.8, 9.68 and 120 pg g-1 dry weight, respectively. PBDEs were the dominant HFRs in mangrove plant tissues, followed by DBDPE. The relative abundance of BDE 209 in three mangrove plant tissues were much lower than those in sediments. Significant negative relationships between log root bioaccumulation factors and log Kow, and between log TFr-s (from root to stem) and log Kow were observed, indicating that HFRs with low hydrophobicity were easily absorbed by mangrove roots and stems. A positive correlation between log TFs-l (from stem to leaf) and log Kow were found, suggesting that air-leaf exchange may occur in mangrove plants. This study highlights the uptake of HFRs by mangrove plants, which can be used as remediation for HFRs contamination in the environment.
Subject(s)
Environmental Monitoring , Flame Retardants , Halogenated Diphenyl Ethers , China , Cities , Environmental PollutantsABSTRACT
Acer tutcheri Duthie is a popular ornamental tree with reddish leaves and bright red fruits. In this study, we report the complete chloroplast genome of it. The cp genome was determined to be 156,973 bp in length, containing a large single copy (LSC) region of 85,356 bp, a small single copy (SSC) region of 18,111 bp and two separated inverted region of 26,753 bp, respectively. It encodes a total of 132 unique genes, including 87 protein-coding genes, 37 tRNA genes and eight rRNA genes. The phylogenetic analysis indicates that A. tutcheri is sister to A. wilsonii Rehd.
ABSTRACT
Brominated flame retardants (BFRs) such as tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs) are of ecological concern due to their ubiquitous presence and adverse effects. There is a paucity of data on environmental fate of such compounds in mangrove wetlands, which are unique ecosystems in coastal intertidal areas and act as natural sinks for many pollutants. In this study, mangrove plants and sediments were collected from an urban nature reserve in South China to investigate bioaccumulation and translocation of TBBPA and HBCDs. The mean (range) concentrations of TBBPA and ΣHBCD in roots, stems and leaves were 67 (Subject(s)
Hydrocarbons, Brominated/metabolism
, Polybrominated Biphenyls/metabolism
, China
, Flame Retardants/analysis
, Hydrocarbons, Brominated/analysis
, Plants/metabolism
, Polybrominated Biphenyls/analysis
ABSTRACT
Polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCDD) and dechlorane plus (DP) were measured in sediments collected from three mangrove wetlands of the Pearl River Estuary (PRE) in South China. This study aims to investigate the distribution of these halogenated flame retardants (HFRs) and the correlations between HFRs and microbial community structure in mangrove sediments. Concentrations of PBDEs, DBDPE, BTBPE, TBBPA, HBCDD and DP in mangrove sediments ranged from 6.97 to 216.1, 3.70-26.0, 0.02-0.73, 0.02-37.5, 0.44-127.5 and 0.07-2.23â¯ng/g dry weight, respectively. Higher levels of PBDEs, BTBPE, HBCDD and DP were observed in sediments from Futian mangrove wetland of Shenzhen, the only nature reserve located in the downtown of China. The highest concentration of TBBPA found in mangrove sediments from Guangzhou was proximate to a ferry terminal and a dockyard where TBBPA is widely used in the coatings. PBDEs were the predominant HFRs in mangrove sediments, with an average contribution of 63.0%. Mangrove sediments from Guangzhou and Zhuhai showed an enrichment of (-)-α-HBCDD, (-)-ß-HBCDD and (-)-γ-HBCDD. Concentrations of HFRs in mangrove sediments from Guangzhou increased significantly from 2012 to 2015, which was probably due to the establishment and rapid development of Nansha Free Trade Zone of Guangzhou. Redundancy analysis showed that HFRs may cause a shift of microbial community structure in mangrove sediments and the variations were significantly correlated with TBBPA, syn-DP and BTBPE.
Subject(s)
Environmental Monitoring/methods , Estuaries , Flame Retardants/analysis , Halogenated Diphenyl Ethers/analysis , Microbiota/drug effects , Wetlands , China , Flame Retardants/pharmacology , Halogenation , Hydrocarbons, Chlorinated/analysis , Polycyclic Compounds/analysis , RiversABSTRACT
Eighteen sediments and four biota species were collected from mangrove wetlands of the Jiulong River Estuary (JRE) in South China to investigate the distribution of dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), dechlorane plus (DP) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). Concentrations of ΣDDTs, ΣPCBs, ΣPBDEs, DBDPE, DP, and BTBPE in mangrove sediments ranged from 21 to 84, 0.52-2.5, 9.0-66, 5.1-32, 0.05-0.14, and 0.03-0.25â¯ng/g dry weight, respectively. Levels of ΣDDTs, ΣPCBs, ΣPBDEs, DBDPE and DP in mangrove biota ranged from 950 to 30000, 56-400, 8.0-35, nd-20 and 0.44-3.1â¯ng/g lipid weight, respectively. DDTs were the predominant halogenated organic pollutants (HOPs) in mangrove sediments from the JRE, while PBDEs were the major HOPs in mangrove sediments from the Pearl River Estuary (PRE), suggesting that sediments in JRE and PRE had different sources of HOPs. The dominance of DDTs was found in both mangrove sediments and biota from the JRE, indicating that HOPs in JRE environment mainly come from agricultural sources. The biota-sediment accumulation factors for DDTs and PCBs were significantly higher than those of PBDEs, DBDPE and DP, suggesting high bioavailability of DDTs and PCBs in mangrove biota. Trophic magnification factors for DDTs, PCBs, PBDEs, and DP were 10.5, 3.00, 2.66 and 1.23, respectively, indicating their potential of biomagnification in mangrove food webs.
Subject(s)
Environmental Monitoring , Estuaries , Water Pollutants, Chemical , Wetlands , China , Environmental Pollutants , Geologic Sediments , Halogenated Diphenyl Ethers , Polychlorinated Biphenyls , RiversABSTRACT
DNA barcoding is a commonly used bio-technology in multiple disciplines including biology, environmental science, forensics and inspection, etc. Forest dynamic plots provide a unique opportunity to carry out large-scale, comparative, and multidisciplinary research for plant DNA barcoding. The paper concisely reviewed four previous progresses in China; specifically, species discrimination, community phylogenetic reconstruction, phylogenetic community structure exploration, and biodiversity index evaluation. Further, we demonstrated three major challenges; specifically, building the impetus to generate DNA barcodes using multiple plant DNA markers for all woody species at forest community levels, analyzing massive DNA barcoding sequence data, and promoting theoretical innovation. Lastly, we raised five possible directions; specifically, proposing a "purpose-driven barcode" fit for multi-level applications, developing new integrative sequencing strategies, pushing DNA barcoding beyond terrestrial ecosystem, constructing national-level DNA barcode sequence libraries for special plant groups, and establishing intelligent identification systems or online server platforms. These efforts will be potentially valuable to explore large-scale biodiversity patterns, the origin and evolution of life, and will also facilitate preservation and utilization of biodiversity resources.
ABSTRACT
To determine how well DNA barcodes from the chloroplast region perform in forest dynamics plots (FDPs) from global CTFS-ForestGEO network, we analyzed DNA barcoding sequences of 1277 plant species from a wide phylogenetic range (3 FDPs in tropics, 5 in subtropics and 5 in temperate zone) and compared the rates of species discrimination (RSD). We quantified RSD by two DNA barcode combinations (rbcL + matK and rbcL + matK + trnH-psbA) using a monophyly-based method (GARLI). We defined two indexes of closely-related taxa (Gm/Gt and S/G ratios) and correlated these ratios with RSD. The combination of rbcL + matK averagely discriminated 88.65%, 83.84% and 72.51% at the local, regional and global scales, respectively. An additional locus trnH-psbA increased RSD by 2.87%, 1.49% and 3.58% correspondingly. RSD varied along a latitudinal gradient and were negatively correlated with ratios of closely-related taxa. Successes of species discrimination generally depend on scales in global FDPs. We suggested that the combination of rbcL + matK + trnH-psbA is currently applicable for DNA barcoding-based phylogenetic studies on forest communities.
Subject(s)
DNA Barcoding, Taxonomic/methods , DNA, Plant/genetics , Phylogeny , Trees/genetics , Chloroplasts/genetics , Climate , Endoribonucleases/genetics , Forests , Gene Expression , Genetic Loci , Histidine-tRNA Ligase/genetics , Nucleotidyltransferases/genetics , Photosystem II Protein Complex/genetics , Ribulose-Bisphosphate Carboxylase/genetics , Sequence Analysis, DNA , Species Specificity , Trees/classificationABSTRACT
Pb and Cd contents in 13 plantation tree species (leaf and branch components), soil, water (groundwater and river water) at a young (3-5 year-old) seashore afforestation stand were investigated in Nansha district, Guangzhou city in southern China. The results showed that (1) soil, rather than water or trees, had the highest content of both Pb (averagely 48.79 mg/kg) and Cd (0.50 mg/kg), demonstrating that soil might function as a major reservoir for extraneously derived heavy metals; (2) Pb content was higher in branches than in leaves, but Cd content appeared similar in both components, implying possibly different accumulation mechanisms in trees; (3) Pb and Cd appeared to accumulate differently among some tree taxa, whereas almost no significant difference was detected between introduced and indigenous species. The study indicated that trees were potentially useful to remediate sites contaminated with Pb and Cd in the urbanized areas.
Subject(s)
Environmental Monitoring/methods , Forests , Metals, Heavy/analysis , Soil Pollutants/analysis , Trees/chemistry , Water Pollutants, Chemical/analysis , Cadmium/analysis , China , Cities , Lead/analysis , Plant Leaves/chemistryABSTRACT
Polycyclic aromatic hydrocarbon (PAH) concentrations and fluxes were measured monthly in situ from rain events in an urban forest in the megapolitan city Guangzhou, China, to investigate impacts of forest canopy and soils on PAHs. Mean Σ9-PAH concentrations were 107.5, 101.6, 106.3, 107.1 and 42.4 ng L(-1) in precipitation, throughfall, seepage water at the 30 and 60 cm soil depth, and runoff, respectively, indicating a great decrease in the form of runoff. Meanwhile, annual fluxes of total PAHs decreased from precipitation (205.9 µg m(-2) year(-1)), to throughfall (156.3 µg m(-2) year(-1)), and to seepage water (65.3 µg m(-2) year(-1) at 30-cm soil depth and 7.5 µg m(-2) year(-1) at 60-cm soil depth), but increased in runoff (34.1 µg m(-2) year(-1)). When compared to precipitation, PAH fluxes decreased by 83.4% in runoff, with 29% contributed by forest canopy and 71% by soils. Soil biodegradation explained 18.2% of PAH reduction by the surface soil layer and 34.6% by the middle soil layer.
Subject(s)
Air Pollutants/analysis , Polycyclic Aromatic Hydrocarbons/analysis , Rain/chemistry , Air Pollutants/metabolism , Biodegradation, Environmental , China , Cities , Forests , Polycyclic Aromatic Hydrocarbons/metabolism , Soil MicrobiologyABSTRACT
Forest dynamics plots, which now span longitudes, latitudes, and habitat types across the globe, offer unparalleled insights into the ecological and evolutionary processes that determine how species are assembled into communities. Understanding phylogenetic relationships among species in a community has become an important component of assessing assembly processes. However, the application of evolutionary information to questions in community ecology has been limited in large part by the lack of accurate estimates of phylogenetic relationships among individual species found within communities, and is particularly limiting in comparisons between communities. Therefore, streamlining and maximizing the information content of these community phylogenies is a priority. To test the viability and advantage of a multi-community phylogeny, we constructed a multi-plot mega-phylogeny of 1347 species of trees across 15 forest dynamics plots in the ForestGEO network using DNA barcode sequence data (rbcL, matK, and psbA-trnH) and compared community phylogenies for each individual plot with respect to support for topology and branch lengths, which affect evolutionary inference of community processes. The levels of taxonomic differentiation across the phylogeny were examined by quantifying the frequency of resolved nodes throughout. In addition, three phylogenetic distance (PD) metrics that are commonly used to infer assembly processes were estimated for each plot [PD, Mean Phylogenetic Distance (MPD), and Mean Nearest Taxon Distance (MNTD)]. Lastly, we examine the partitioning of phylogenetic diversity among community plots through quantification of inter-community MPD and MNTD. Overall, evolutionary relationships were highly resolved across the DNA barcode-based mega-phylogeny, and phylogenetic resolution for each community plot was improved when estimated within the context of the mega-phylogeny. Likewise, when compared with phylogenies for individual plots, estimates of phylogenetic diversity in the mega-phylogeny were more consistent, thereby removing a potential source of bias at the plot-level, and demonstrating the value of assessing phylogenetic relationships simultaneously within a mega-phylogeny. An unexpected result of the comparisons among plots based on the mega-phylogeny was that the communities in the ForestGEO plots in general appear to be assemblages of more closely related species than expected by chance, and that differentiation among communities is very low, suggesting deep floristic connections among communities and new avenues for future analyses in community ecology.
ABSTRACT
During the rainy season (April-September) of 2012, the atmospheric particulate matter with a diameter less than 2.5 mm (PM2.5) were sampled from the forest parks in the urban area, suburban area, and rural area of Guangzhou City. The mass concentration of PM2.5 and its water-soluble ions (SO4(2-), NO3-, NO2-, Cl-, F-, Na+, NH4+, Ca2+, K+, and Mg2+) contents were also measured. In the forest parks in the urban area, suburban area, and rural area, the diurnal variation of PM2.5 mass concentration was 21.8-161.7, 19.4-156.3, and 17.2-66.5 microg x m(-3), with an arithmetic average being 55.9, 49.8, and 44.4 microg x m(-3), respectively. SO4(2-), Na+, and NH4+ were the main components of water-soluble ions in the PM2.5, and the SO4(2-) had the highest content and decreased gradually from urban to rural forest parks. The contribution of the SO2 and NOx in the PM2.5 from coal combustion to the forest parks was larger than that from vehicle exhaust, but presented a decreasing trend from urban to rural forest parks, indicating that vehicle exhaust had a greater contribution to the atmospheric SO2 and NOx in the urban forest park. In the sampling period, the contribution of sea salt to the water soluble fractions (especially K+) of the PM2.5 was greater for the suburban forest park than for the other two parks. The equivalent concentration of the NH4+ in the PM2.5 was far less than those of the SO4(2-) and NO3-, with a neutralization ratio being much lower than 1.0, which suggested that the PM2.5 had a higher acidity. The PM2.5 acidity had an increasing trend from rural to urban forest parks.
Subject(s)
Air Pollutants/analysis , Environmental Monitoring , Particulate Matter/analysis , Rain , Trees/growth & development , Atmosphere/analysis , China , Cities , Ions/analysis , Seasons , SolubilityABSTRACT
It is crucial for the studies of taxonomy and biodiversity by using DNA barcode technology to fast and accurately make species identification in the forests across tropics and temperate zones. In this study, the 183 plant species in a 20 hm2 subtropical forest plot in Dinghushan (DHS) National Nature Reserve of South China were sampled and sequenced, and the matK, rbcL, and psbA-trnH were employed to generate multi-locus barcodes. For the plot, the psbA-trnH possessed the highest integral success rate, i. e., the product of sequencing recovery and correct species identification (75%), followed by matK (70%), and rbcL (56%). A combination of three-locus barcode (matK, rbcL and psbA-trnH) could identify greater than 87% of the total species, followed by two-locus barcode (85% for matK+psbA-trnH, 83% for rbcL+psbA-trnH, and 81% for matK+rbcL). A comparison was made with the previously published results from one subtropical forest plot (LFDP in Puerto Rico, 143 species) and two tropical forest plots (BCI in Panama, 296 species; and NRS in French Guiana, 254 species) to evaluate the universality and species identification correctness of the proposed DNA barcodes for these four forest plots. For the plots in tropics and subtropics, the sequencing success rate of rbcL, psbA-trnH and matK were 93% and 95.1%, 91.5% and 94.6%, and 68.5% and 79.7%, respectively. The combination of matK + rbcL showed a high identification capacity in geographically restricted regions in taxonomic groups, whereas the three-locus barcode had a high rate of correct species identification both in tropics (84%) and in subtropics (90%).
Subject(s)
DNA Barcoding, Taxonomic/methods , DNA, Plant/analysis , Plants/classification , Plants/genetics , DNA, Plant/genetics , DNA, Plant/isolation & purification , Ecosystem , Species SpecificityABSTRACT
Elucidating the ecological mechanisms underlying community assembly in subtropical forests remains a central challenge for ecologists. The assembly of species into communities can be due to interspecific differences in habitat associations, and there is increasing evidence that these associations may have an underlying phylogenetic structure in contemporary terrestrial communities. In other words, by examining the degree to which closely related species prefer similar habitats and the degree to which they co-occur, ecologists are able to infer the mechanisms underlying community assembly. Here we implement this approach in a diverse subtropical tree community in China using a long-term forest dynamics plot and a molecular phylogeny generated from three DNA barcode loci. We find that there is phylogenetic signal in plant-habitat associations (i.e. closely related species tend to prefer similar habitats) and that patterns of co-occurrence within habitats are typically non-random with respect to phylogeny. In particular, we found phylogenetic clustering in valley and low-slope habitats in this forest, indicating a filtering of lineages plays a dominant role in structuring communities in these habitats and we found evidence of phylogenetic overdispersion in high-slope, ridge-top and high-gully habitats, indicating that distantly related species tended to co-occur in these high elevation habitats and that lineage filtering is less important in structuring these communities. Thus we infer that non-neutral niche-based processes acting upon evolutionarily conserved habitat preferences explain the assembly of local scale communities in the forest studied.