Phylogenetic trees have been extensively used in community ecology. However, how the phylogeny construction affects ecological inferences is poorly understood. In this study, we constructed three ...different types of phylogenetic trees (a synthetic‐tree generated using V.PhyloMaker, a barcode‐tree generated using rbcL+matK+trnH‐psbA, and a plastome‐tree generated from plastid genomes) that represented an increasing level of phylogenetic resolution among 580 woody plant species from six forest dynamic plots in subtropical evergreen broadleaved forests of China. We then evaluated the performance of each phylogeny in estimations of community phylogenetic structure, turnover and phylogenetic signal in functional traits. As expected, the plastome‐tree was most resolved and most supported for relationships among species. For local phylogenetic structure, the three trees showed consistent results with Faith's PD and MPD; however, only the synthetic‐tree produced significant clustering patterns using MNTD for some plots. For phylogenetic turnover, contrasting results between the molecular trees and the synthetic‐tree occurred only with nearest neighbor distance. The barcode‐tree agreed more with the plastome‐tree than the synthetic‐tree for both phylogenetic structure and turnover. For functional traits, both the barcode‐tree and plastome‐tree detected phylogenetic signal in maximum height, but only the plastome‐tree detected signal in leaf width. This is the first study that uses plastid genomes in large‐scale community phylogenetics. Our results highlight the improvement of plastome‐trees over barcode‐trees and synthetic‐trees for the analyses studied here. Our results also point to the possibility of type I and II errors in estimation of phylogenetic structure and turnover and detection of phylogenetic signal when using synthetic‐trees.
Aim
The equator‐to‐poles decline in the number of species, namely the latitudinal diversity gradient (LDG), is the most conspicuous pattern in biology, yet the underlying mechanisms of this pattern ...remain controversial. Species dispersal could have strong effects on large‐scale species distributions but has rarely been considered in understanding the LDG. Here we sought to examine how dispersal ability may influence the latitudinal phylogenetic patterns of woody angiosperm assemblages.
Location
China.
Taxon
Woody angiosperms.
Methods
Based on a highly supported mega‐phylogeny constructed from plastid genomes, we assessed the patterns of phylogenetic relatedness and dissimilarity of 1184 trees with three different seed dispersal modes (i.e. zoochory, anemochory and autochory) in 12 permanent forest dynamic plots covering tropical, subtropical and temperate zones in China.
Results
We found that, compared with zoochorous and anemochorous species, the less vagile autochorous trees exhibited a much weaker latitudinal pattern in phylogenetic relatedness and higher phylogenetic dissimilarity among plots. The phylogenetic dissimilarity pattern of autochorous trees was explained more by geographic distance than environmental factors, consistent with a dominant role for dispersal limitation.
Main Conclusions
Our study, for the first time, demonstrates that seed dispersal mode strongly influences the latitudinal phylogenetic patterns of woody angiosperm assemblages in China and highlights the importance of interaction between dispersal limitation and environmental filtering in determining the large‐scale distribution of forest biodiversity.
The application of DNA barcoding has been significantly limited by the scarcity of reliable specimens and inadequate coverage and replication across all species. The deficiency of DNA barcode ...reference coverage is particularly striking for highly biodiverse subtropical and tropical regions. In this study, we present a comprehensive barcode library for woody plants in tropical and subtropical China. Our dataset includes a standard barcode library comprising the four most widely used barcodes (rbcL, matK, ITS, and ITS2) for 2,520 species from 4,654 samples across 49 orders, 144 families, and 693 genera, along with 79 samples identified at the genus level. This dataset also provides a super-barcode library consisting of 1,239 samples from 1,139 species, 411 genera, 113 families, and 40 orders. This newly developed library will serve as a valuable resource for DNA barcoding research in tropical and subtropical China and bordering countries, enable more accurate species identification, and contribute to the conservation and management of tropical and subtropical forests.
Quantifying spatial patterns of species richness and determining the processes that give rise to these patterns are core problems in biodiversity theory. The aim of the present paper was to more ...accurately detect patterns of vascular species richness at different scales along altitudinal gradients in order to further our understanding of biodiversity patterns and to facilitate studies on relationships between biodiversity and environmental factors. Species richness patterns of total vascular plants species, including trees, shrubs, and herbs, were measured along an altitudinal gradient on one transect on a shady slope in the Dongling Mountains, near Beijing, China. Direct gradient analysis, regression analysis, and geostatistics were applied to describe the spatial patterns of species richness. We found that total vascular species richness did not exhibit a linear pattern of change with altitude, although species groups with different ecological features showed strong elevational patterns different from total species richness. In addition to total vascular plants, analysis of trees, shrubs, and herbs demonstrated remarkable hierarchical structures of species richness with altitude (i.e. patchy structures at small scales and gradients at large scales). Species richness for trees and shrubs had similar spatial characteristics at different scales, but differed from herbs. These results indicated that species groups with similar ecological features exhibit similar biodiversity patterns with altitude, and studies of biodiversity based on species groups with similar ecological properties or life forms would advance our understanding of variations in species diversity. Furthermore, the gradients or trends appeared to be due mainly to local variations in species richness means with altitude. We also found that the range of spatial scale dependencies of species richness for total vascular plants, trees, shrubs, and herbs was relatively large. Thus, to detect the relationships between species richness with environmental factors along altitudinal gradients, it was necessary to quantify the scale dependencies of environmental factors in the sampling design or when establishing non‐linear models.
(Managing editor: Ya‐Qin Han)
To the Editor： A 56-year-old Chinese man was referred to Peking Union Medical College Hospital because of polydipsia （9000 ml/24 h） and polyuria （7000 ml/24 h） for over 20 days accompanied with ...intermittent moderate headache in frontal and temporal areas of both sides for about 2 weeks. The patient underwent a brain magnetic resonance imaging （MRI） with contrast in a local healthy facility, revealing that there was an irregular pituitary lesion measuring 1.1 cm× 1.4 cm× 2.2 cm. Apparently, the diagnosis of central diabetes insipidus （DI） was made, but the pituitary lesion remained to be elucidated. The patient received desmopressin acetate tablets （1.2 mg, q.n.） to ameliorate polydipsia （5000 ml/24 h） and polyuria （4000 ml/24 h）.
Phylobetadiversity incorporates phylogenetic information and beta diversity, and can account for the ecological similarities between communities with a phylogenetic perspective. Although different ...phylobetadiversity indices reflect differences in different characteristics between communities, the results of different phylobetadiversity indices are not comparable. In this study we examined phylobetadiversity indices for a 24-hm2 plot in the Gutianshan National Nature Reserve. It was found the abundance-weighted D pw was almost identical to Rao’s D of Rao’s quadratic entropy. PhyloSor had a similar ecological meaning and algorithm to UniFrac. Although D nn was different in definition from UniFrac and PhyloSor, they were all strongly correlated. The effect of species abundance on phylobetadiversity was not significant when scales were relatively small, but was significant at larger scales. These contrasts likely resulted from reductions in evenness in communities as scales increased. P ST and Rao’s H better reflected the distance-decay changes caused by spatial and habitat variation than other indices at larger scales, whereas AW-D nn and D nn better reflected these changes at small scales.
With the full survey data for a 24-ha subtropical evergreen broad-leaved forest dynamics plot, we evaluated spatial variation in forest structure characteristics (basal area and aboveground biomass), ...and calculated the minimal sample size and total sampling area necessary to estimate the forest structure characteristics within 20% (±10%) of the observed values with 95% probability for particular quadrat sizes by using a computer program that is designed to simulate the sampling process by allowing different sized quadrats to be randomly located within the sampling region. We found that (1) based on the 600 20 m×20 m subplots, basal area and aboveground biomass displayed a high degree of variation, with respective coefficients of variation of 27% and 31%; (2) based on the computer simulation analysis, the variability of basal area and aboveground biomass decreased with increasing quadrat size. The number of quadrats required to achieve the specified degree of precision dropped sharply with the increase of quadrat size. However, the total sampling area increased with increasing quadrat size, suggesting that using several small quadrats across the sampling area is more efficient than using fewer larger quadrats. Results of this study are valuable for evaluating the reliability of previous research and may assist researchers in designing effective sampling strategies for future field surveys, particularly in subtropical evergreen broad-leaved forests in China.
With the escalating demand for fast simulation of large-scale multi-input multi-output (MIMO) RCS circuits formulated as second-order differential systems, the need arises for more effective ...decentralized second-order model order reduction (MOR) methods, while providing a desired approximation of the original system. Dynamic relative gain array (DRGA) that takes into account both the steady-state and dynamic system information has shown promising efficacy in measuring the degree of each loop interaction, which is crucial for decoupling a MIMO system into several multi-input single-output (MISO) subsystems. Although several decentralized MOR methods have been introduced for dimension reduction to linear MIMO networks, hardly has any research explored second-order decentralized MOR methods with regard to MIMO RCS circuits. Besides, the existing DRGA method based on first-order state feedback predictive control greatly increases the computational complexity when directly applying to second-order RCS systems. Hence, we develop a second-order block Arnoldi method based on DRGA, termed DRGA-SOBAR, which enables the extension of the SOAR method and the second-order DRGA method to MIMO scenarios. Experimental results on RCS networks show that most input-output interactions are negligible in terms of the magnitude-wise insignificance, and our proposed DRGA-SOBAR based reduced systems perform with higher accuracy compared to the PRIMA and the generalized block SOAR (SOBAR) methods, and higher efficiency compared to the decentralized SOBAR algorithm based on RGA method as well.
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