Species Associations in a Species-Rich Subtropical Forest Were Not Well-Explained by Stochastic Geometry of Biodiversity

The stochastic dilution hypothesis has been proposed to explain species coexistence in species-rich communities. The relative importance of the stochastic dilution effects with respect to other effects such as competition and habitat filtering required to be tested. In this study, using data from a 25-ha species-rich subtropical forest plot with a strong topographic structure at Badagongshan in central China, we analyzed overall species associations and fine-scale species interactions between 2,550 species pairs. The result showed that: (1) the proportion of segregation in overall species association analysis at 2 m neighborhood in this plot followed the prediction of the stochastic dilution hypothesis that segregations should decrease with species richness but that at 10 m neighborhood was higher than the prediction. (2) The proportion of no association type was lower than the expectation of stochastic dilution hypothesis. (3) Fine-scale species interaction analyses using Heterogeneous Poisson processes as null models revealed a high proportion (47%) of significant species effects. However, the assumption of separation of scale of this method was not fully met in this plot with a strong fine-scale topographic structure. We also found that for species within the same families, fine-scale positive species interactions occurred more frequently and negative ones occurred less frequently than expected by chance. These results suggested effects of environmental filtering other than species interaction in this forest. (4) We also found that arbor species showed a much higher proportion of significant fine-scale species interactions (66%) than shrub species (18%). We concluded that the stochastic dilution hypothesis only be partly supported and environmental filtering left discernible spatial signals in the spatial associations between species in this species-rich subtropical forest with a strong topographic structure.     

Guadalupe Island: Lost paradise recovered? Overgrazing impact on extinction in a remote oceanic island as estimated through accumulation functions

Guadalupe Island, an oceanic island in the northwest of Mexico, is an outlier of the California Floristic Province that has been disturbed by introduced goats for more than a century, with dramatic effects of goats on plant communities and local species extinctions. In 2004 the island went through a successful eradication program. Since then, six previously unrecorded species have been discovered and four supposed extinct species have been found again. Quantifying the true species richness of the island at the time of eradication, to set a benchmark for the future monitoring of this large-scale natural experiment, is both a challenge and a necessity. For this purpose, we estimated (a) current and (b) accumulated historical plant species richness of the island through accumulation functions. Estimation of current species richness was based on the geographical accumulation process of species richness (80 species) obtained from sampling 110 (50 m × 2 m) transects distributed along the island in year 2004. Historical species richness was estimated through the temporal accumulation of species richness (119 species) from botanical records (1,960 specimens reviewed) between 1875 and 2000. The predicted value of historical richness (213 species) is similar to known historical records (218 species), but estimation of current richness (203 species) is significantly higher than accepted extant plant richness (187 species). Our results suggest that currently there may be more plant species living in the island than estimated through recent botanical exploration. Future monitoring of the island as it recovers will clarify this hypothesis.     

Do McKinnon lists provide reliable data in bird species frequency? A comparison with transect-based data

Although occurrence-based listing methods could provide reliable lists of species composition for a site, the effective reliability of this method to provide more detailed information about species frequency (and abundance) has been rarely tested. In this paper, we compared the species frequencies obtained for the same set of species-rich sites (wetlands of central Italy) from two different methods: McKinnon lists and line transects. In all sites we observed: (i) rapid cumulating curves of line transect abundance frequencies toward the asymptote represented by the maximum value in McKinnon occurrence frequency; (ii) a large amount of species having a low frequency with line transect method showing a high range of variation in frequency obtained by McKinnon lists; (iii) a set of species having a subdominant (>0.02-<0.05) and dominant species (>0.05) frequency with line transect showed all the highest value in McKinnon frequency. McKinnon lists provides only a coarse-grained proxy of species frequency of individuals distinguishing only between common species (having the highest values of McKinnon frequency) and rare species (all the other species). Although McKinnon lists have some points of strength, this method does not discriminate the frequencies inside the subset of common species (sub-dominant and dominant species). Therefore, we suggest a cautionary approach when McKinnon frequencies should be used to obtain complex univariate metrics of diversity.     

贡嘎山石松类和蕨类植物的多样性与海拔分布（附表）

贡嘎山是横断山脉海拔最高的一座大山,是研究山地植物多样性和海拔分布的理想地区。为了探讨贡嘎山地区石松类和蕨类植物多样性组成及海拔分布特点,该研究基于野外考察、标本采集鉴定及文献考证,对贡嘎山地区石松类和蕨类植物进行统计和分析。结果表明:(1)贡嘎山地区有石松类植物3科4属25种,蕨类植物有23科56属291种。(2)主要的珍稀濒危植物有6种,分别是高寒水韭(Iso tes hypsophila)、松叶蕨(Psilotum nudum)、桫椤(Alsophila spinulosa)、小叶中国蕨(Aleuritopteris albofusca)、玉龙蕨(Polystichum glaciale)和扇蕨(Lepisorus palmatopedatus)。(3)优势科为鳞毛蕨科(Dryopteridaceae)75种、水龙骨科(Polypodiaceae)56种、凤尾蕨科(Pteridaceae)54种和蹄盖蕨科(Athyriaceae)37种;优势属为耳蕨属(Polystichum)45种、鳞毛蕨属(Dryopteris)24种、蹄盖蕨属(Athyrium)24种和瓦韦属(Lepisorus)19种。(4)区系以温带成分为主,有286种(93.77%)。随着海拔的上升,石松类和蕨类的物种多样性逐渐增加,2000~3000 m海拔段的物种多样性最高,为20科46属192种,3000 m以上物种多样性逐渐下降,4500 m以上仅分布有4种蕨类植物。此外,该研究还发现,随着海拔的升高,中国-喜马拉雅成分逐渐增加。     

陕西汉中地区蝗虫种类及区系特点

汉中地区的蝗总科昆虫有5科33属51种,锥头蝗科Pyrgomorphidae1属2种,斑腿蝗科Catantopidae9属19种,网翅蝗科Arcypteridae5属12种,斑翅蝗科Oedipodidae12属13种,剑角蝗科Acrididae5属5种。汉中地区蝗总科的昆虫以东洋界为主,共23种,占45.1%,其次为汉中地区特有种类10种,占19.6%,古北界和两界共有种类均为9种,均占17.6%。物种数量在各县区分布不均匀。     

黔桂边境六县植物区系组成及其特点

黔桂边境六县植物区系有维管束植物203科921属2255种(变种)。其中种子植物含25种以上的有22科,代表成分有樟科、山茶科、壳斗科、五加科、桑科和椴树科。区系的特点是:地理成分复杂、分布交错;热带、亚热带性质明显;区系起源古老;特有珍稀种类多;喜酸成分较喜钙成分占优势;草本与木本种类近等。此外,对本区系自然条件及植物资源利用也作了简述。     

A functional classification of wetland plants

Abstract. In this paper we review the search for guilds in plant communities, and provide a summary of the process, emphasizing five steps: (1) defining function, (2) selecting traits which reflect function, (3) screening for those traits, (4) constructing trait matrices, and (5) grouping species according to these traits. We illustrate this process for wetland plant species based upon a matrix of 27 traits and 43 species from across eastern North America. The 43 species were selected to represent the widest range of life history types possible as well as both common species and nationally rare or endangered species. We found three main functional groups: ruderals, matrix and interstitial species, which we subdivide into a total of seven guilds. The growing number of such studies in the literature suggest that this may be an expedient measure for conservation biology and a promising one for predictions.     

Can the mass effect explain the mid-altitudinal peak in vascular plant species richness?

A mid-altitudinal peak in species richness is commonly observed and the mass effect (or source–sink effect) has been suggested as a possible cause. We test the importance of the mass effect for generating altitudinal patterns of plant species richness at two grain sizes using a simple estimate of sterility/fertility to indicate sinks and sources. To do this we identified species with fertile specimens (fertile species) and species with only sterile specimens (sterile species) in each sampling unit along altitudinal transects and assumed that the number of sterile species indicated the relative number of sink species, correspondingly that the number of fertile species indicated the relative number of source species when looking at the overall pattern of species richness along a transect. To evaluate this approach, we investigated the distribution of sterility and fertility of each species along the altitudinal transects. We found that sterile species are found more often at the edges and fertile species more often in the centre of the species altitudinal ranges than expected by chance. Using a fine grain, sterile species richness had a humped altitudinal pattern on all transects investigated at this scale, whereas using a coarse grain two of the three transects investigated had a humped pattern. At the fine grain, sterile species richness had a more pronounced peak than fertile species richness in two of the three transects investigated supporting the hypothesis of the mass effect, but this pattern did not persist at coarser grain. The observations at the fine grain are in accordance with the idea that the mass effect is important in shaping the mid-altitudinal peak in species richness, whereas the observations from the coarser grain are ambiguous.     

Length–Weight relationships of 23 fish species from floodplain ecosystems of the Andean Amazon piedmont,Peru

Length–weight relationships (LWRs) for 23 freshwater fish species from the Andean Amazon piedmont in Peru are presented in this study. Fishes were captured between 2009 and 2010 on lagoons from three basins; Amazonas (Ampiyacu and Apayacu) and Ucayali (Pachitea) using gillnets. In this study, new LWRs are reported for 20 species of 23 species analyzed. The study provides new information on less‐studied species and can serve as a basis for management of fisheries and conservation of this area.     

新疆焉耆盆地种子植物区系特征分析

焉耆盆地位于新疆天山中段南麓,在植被地理区划上属于新疆暖温带灌木、半灌木荒漠区,其独特的自然地理位置和生态环境孕育了较为丰富的植物资源,研究其种子植物区系多样性分布特点对该区植物资源保护及可持续开发利用具有极其重要的意义。本研究通过野外实地调查及查阅相关文献资料,对新疆焉耆盆地的种子植物区系分布特点进行了系统分析。结果显示,该区种子植物约有1035种,隶属于80科373属,其中新疆特有种有38种,占新疆特有种总种数的14.18%。区系地理成分中,在科级水平上,焉耆盆地种子植物80科可划分为6个分布区类型和7个变型,并以温带地理成分为主(共有22个科),占该区非世界分布科总科数的57.89%;在属级水平上,焉耆盆地种子植物373属可划分为12个分布区类型和17个变型,并以温带地理成分为主(共197属),占非世界分布属总属数的62.54%。焉耆盆地种子植物生活型中,草本植物占优势,共有901种,占该区种子植物总种数的87.05%;灌木有110种(占10.63%),乔木17种(占1.64%),藤本7种(占0.68%)。焉耆盆地种子植物生态类型中,中生类型676种,占该区种子植物总种数的65.31%;旱生类型有191种(占18.45%),湿生类型123种(占11.88%),水生类型45种(占4.35%)。     

Diversity and distribution of Collembola (Arthropoda: Hexapoda) of Brazil

Objectives of this study are to summarize the current state of knowledge of the diversity and distribution of Collembola in Brazil; to identify areas of most importance, interest, and need of additional research; and to enable development of experimental hypotheses for future research on Collembola in this region. The total number of collembolan species currently known from Brazil is 199, distributed among 19 families and 80 genera. The greatest numbers of species have been recorded from the states of Rio de Janeiro and Amazonas (with 69 and 56 species, respectively). Few or no species are known from most Brazilian states. Most of the species for which specific Brazilian environmental habitat information is available (93, 66%) are known only from forest environments. Most of the species (127, 64%) are known only from Brazil (most likely being endemic); 33 species (17%) are known only from Brazil and other neotropical areas; and 39 species (20%) have a distribution beyond the neotropical region. Results of this study indicate that much remains to be learned about the Brazilian collembolan fauna. This is especially true for areas of the northeastern, central-western, and southern regions. Studies to determine the species composition of collembolan communities in specific environments in Brazil are needed. The great diversity of Collembola species in Brazil is largely unknown and there are many opportunities for additional research on these environmentally important organisms in this area. Such additional research on the Collembola in Brazil is also essential for a better understanding of the neotropical (and world) collembolan fauna.     

The selection of marmoset monkeys (Callithrix jacchus) in pharmaceutical toxicology

Prior to controlled clinical trials in human volunteers or patients it is required that novel pharmaceuticals are evaluated for pre-clinical safety in a rodent and a non-rodent ('second') species. In most cases the rodent species used has been the rat and the second species has been the dog or macaque (usually cynomolgus or rhesus) monkey. However, there is an increasing trend within the United Kingdom (UK) pharmaceutical industry to use the common marmoset (Callithrix jacchus) for pre-clinical toxicology programmes. This paper examines the practicality of using the common marmoset (henceforth referred to as 'the marmoset') in toxicological testing and reviews metabolic and pharmacodynamic similarities between this species and humans. It then discusses some of the advantages and disadvantages of the use of this species when compared with two other alternatives to the dog and macaque, namely the ferret and minipig. In particular, the marmoset has clear advantages over the macaque in terms of animal welfare and practicality. There is regulatory acceptance of this species for Investigational New Drug (IND), Clinical Trial Exemption (CTX), New Drug Application (NDA) and Marketing Authorization Application (MAA) registrations. Whilst the dog is likely to be maintained as the primary non-rodent species in toxicology, the marmoset has been, and will likely continue to be, adopted as an additional non-rodent species in pre-clinical toxicology programmes where appropriate.     

The use of wild edible plants in western and central Anatolia (Turkey)

In this study, 121 wild edible plants used as food in Anatolia were surveyed to determine the plant parts used and their detailed preparation methods. The results of this study show that the plants may be boiled, fried in fat, and eaten raw or as rolled vegetables. They may also be consumed as pickles, fruits, sweets and spices, and drunk as cold and hot drinks. Thirty species (8 genera) were identified as belonging to the Lamiaceae family, 15 species (15 genera) belong to the Asteraceae family, 13 species (5 genera) belong to the Rosaceae family, 8 species (7 genera) belong to the Brassicaceae family, 6 species (3 genera) belong to the Orchidaceae family and 5 species (5 genera) belong to the Apiaceae family. The genera represented by the highest number of species in the study are as follows:Sideritis L. is represented by 13 species, Origanum L. by 7 species,Rubus L. by 5 species,Thymus L. by 4 species andRumex L. by 4 species.     

Competition between two microbial populations in a nonmixed environment: effect of cell random motility

In a nonmixed environment, bacterial population growth can be influenced significantly by cell motility properties as well as by growth kinetic properties. Therefore, in a situation of competition between two bacterial populations for a single chemical nutrient in a nonmixed environment, the outcome may depend upon the respective cell motility properties. In this article, the authors have presented a simple mathematical model for competitive growth of two randomly motile (i.e., possessing no chemotactic behavior) populations in a finite nonmixed region. An understanding of the behavior of this model should provide insight into the behavior of a number of common microbial competition problems. Analysis of this model yields the following results: (1) There may be as many as three possible non-trivial steady-state (or long-time) configurations: when species 1 survives, species 2 dies out; when species 2 survives, species 1 dies out; and species 1 and species 2 coexist. (2) The coexistence state can exist even though one species possesses a smaller intrinsic growth rate constant at all nutrient concentrations, if that same species is sufficiently less motile than the other species. (3) In fact, the species with the smaller maximum specific growth rate may grow to a larger population than the other. (4) The possibility of coexistence can be decided essentially from the results for single population growth.     

甘南亚高寒草甸稀有种对物种多样性和物种多度分布格局的贡献

稀有种不仅影响群落的物种多度分布格局, 同时也是α多样性的重要贡献者。本研究主要通过加性分配和Fortran软件的RAD程序包拟合的方法, 研究了甘南亚高寒草甸不同坡向物种多样性及多度分布格局的变化, 分析了物种多度分布格局及其α多样性的变化特征, 确定了稀有种在物种多度分布格局中的相对贡献。结果表明: (1)在南坡到北坡的变化中, 环境因子差异比较明显, 其中, 土壤全磷、有机碳、速效磷、碳氮比及含水量呈递增趋势; 土壤氮磷比和pH值呈递减趋势; 土壤全氮在西坡显著低于其他坡向, 而速效氮在所有坡向上差异不显著。(2)稀有种对群落物种多样性的影响在南-北坡向梯度上依次增大, 去除稀有种的影响在各坡向均高于去除非稀有种, 可见, 稀有种在甘南亚高寒草甸物种多样性中的相对贡献高于非稀有种。(3)各坡向的稀有种资源获取模式以随机分配占领模式(random fraction模型)为主, 而非稀有种则以生态位优先占领模式(geometric series模型)为主。由于稀有种有较大的扩散率, 在物种多样性较高的生态系统中, 物种之间的生态位重叠会更加明显, 从而抑制物种多样性的增加, 因此能达到维持原有物种多样性的目的。     

四川美姑大风顶自然保护区两栖爬行动物资源调查

20 0 2年 8月 1日～ 17日对四川美姑大风顶自然保护区的两栖爬行动物进行了调查。结合前人的工作 ,该保护区共有两栖爬行动物 2 2种 ,其中两栖动物 11种 ,隶属于 9属 7科 2目 ,爬行动物 11种 ,隶属于 9属 4科 2亚目 1目。区系特点为 :(1)物种组成较丰富 ;(2 )都属于东洋界物种 ,没有古北界的成分 ;(3)区系组成较简单 ,以喜马控雅 -横断山区型和南中国型为主 ;(4 )特有种所占比例高。 (5 )既古老又具年轻的特点。美姑县新纪录 6种 ,大凉疣螈为国家Ⅱ级重点保护野生动物 ,横斑锦蛇为四川省重点保护野生动物。美姑大风顶自然保护区两栖爬行动物物种多样性和生境多样性较高 ,对于生物多样性保护和研究横断山脉两栖爬行动物物种组成及区系特征具有一定意义。     

Vigilance towards raptors by nuclear species in bird mixed flocks in a Brazilian savannah

A nuclear or leader species is the one around which foraging activity is organized. In the campo-cerrado (Brazilian savannah) up to four bird species (Saltator atricollis, Cypsnagra hirundinacea, Mimus saturninus, and Neothraupis fasciata) may function as nuclear or leader species in mixed species flocks. The aim of this study was to assess the features shown by these nuclear species. I quantified parameters of sociality, communication and alertness of nuclear bird species in mixed flocks with different composition. Parameters related to sociality (mean intraspecific group size) and communication (frequency of contact calls) were not correlated with the leadership. On the other hand, the most alert species was in the front of a given mixed flock most of the time. The leader species spent more time in vigilance and gave most alarm calls due to approaching raptors earlier. The results of this study strongly suggest that the alertness of a species is the major character of nuclear bird species in mixed flocks of the campo-cerrado.     

Taxonomy,population status and ecology of Indian desert monitor lizard Varanus griseus koniecznyi Mertens 1954 in the Thar desert of Rajasthan

Among monitor lizards of the family Varanidae, Indian desert monitor lizard Varanus griseus koniecznyi Mertens 1954 is one of the lesser-known species globally and due to lack of data on this species it is so far not evaluated by IUCN and excluded from the latest assessment of monitor lizards of Southeast Asia and Indo-Australian Archipelago. The present study was undertaken from January 2013 to June 2017 to fill this gap during which taxonomic evaluation along with an assessment of population and ecology of this species was carried out in the Thar desert of Rajasthan (TDR). The study brought into knowledge many morphological variations along with intraspecific variations of scale microstructure of this lizard. The population density was found to be highest in the Jaisalmer (0.102/ha) district of western Rajasthan, followed by Bikaner (0.08/ha) and Sikar (0.077/ha) districts. The overall population was quite low (0.068/ha) in the area. The study further revealed the species is habitat specialist and lives in a narrow range of habitats and microhabitats, and hence, the species may not adapt to the rapidly changing environment in the TDR. Their activity was found to be highest between 9ndash;12 hrs followed by 12–15 hrs and foraging was found to be their predominant activity followed by resting and feeding. In the absence of any detailed study on this species, the study points towards immediate conservation efforts for the species in its current distribution. Baseline data generated through this study will no doubt help to safeguard the species in the TDR and further research on this species in the future.     

Erysiphe abbreviata on cherry bark oak--morphology, phylogeny and taxonomy

Powdery mildew on cherry bark oak (Quercus falcate var. pagodifolia) collected in Tennessee, USA, was determined to be Erysiphe abbreviata, a species confined to North America. The diagnostically important anamorph of this species is described for the first time. Sequence analyses of the rDNA ITS region and D1/D2 domains of the 28S rDNA were used to obtain phylogenetic data for and taxonomic conclusions about this species. The structure of the anamorph (Oidium subgen. Pseudoidium) and the molecular data support the placement of this species in Erysiphe emend. (including Microsphaera) as a species separate from the Eurasian Erysiphe alphitoides.     

Aggregated spatial distributions of species in a subtropical karst forest,southwestern China

Aims Spatial distribution patterns of species reflect not only the ecological processes but also the habitat features that are related to species distribution. In karst topography, species distribution patterns provide more specific information about their environments. The objectives of this study are as follows: (i) to analyse and explain the spatial distribution patterns of conspecific trees in an old-growth subtropical karst forest; (ii) to investigate pattern changes at different spatial scales; (iii) to test the spatial pattern similarity (or dissimilarity) between trees at different abundances, diameter at breast height classes, canopy layers and different functional groups (shade tolerance and seed dispersal mode); (iv) to examine whether habitat heterogeneity has an important effect on the species spatial distribution.Methods The spatial distributions of woody species with ≥20 individuals in a 1-ha subtropical karst forest plot at Maolan in southwestern China were quantified using the relative neighbourhood density Ω based on the average density of conspecific species in a circular neighbourhood around each species.Important findings Aggregated distribution is the dominant pattern in the karst forest, but the ratio of aggregated species in total species number decreases with an increase in spatial scale. Less abundant species are more aggregated than most abundant species. Aggregation is weaker in larger diameter classes, which is consistent with the prediction of self-thinning. Seed dispersal mode influences spatial patterns, with species dispersed by animals being less aggregated than those dispersed by wind and gravity. Other species functional traits (e.g. shade tolerance) also influence the species spatial distributions. Moreover, differences among species habitat associations, e.g. with rocky outcrops, play a significant role in species spatial distributions. These results indicate that habitat heterogeneity, seed dispersal limitation and self-thinning primarily contribute to the species spatial distributions in this subtropical karst forest.