长江流域淡水软体动物物种多样性及其分布格局

研究以正式发表的淡水软体动物文献和部分未发表野外调查数据为基础资料,分析了长江流域淡水软体动物物种多样性及分布格局。长江流域已报道的软体动物有296种,隶属17科62属,其中有197种是中国特有种。田螺科、肋蜷科、盖螺科、椎实螺科和蚌科是长江流域软体动物的主要组成部分,这5科种类数之和达249种,占总数的84.1%。从总体上低海拔地区的软体动物物种数高于高海拔地区,而高海拔地区特有种所占的比例却高于低海拔地区。支流和湖泊的种类数接近,分别为202种和210种,远高于长江干流（31种）。各水系软体动物的种类数、特有种数及特有种比例明显不同,洞庭湖水系和鄱阳湖水系的多样性最高。聚类分析表明,长江流域软体动物的分布基本反映了流域内的地势特点,形成了高原、中低海拔山地和低海拔平原的分布格局。不同类群的物种其分布格局也不相同,田螺科和椎实螺科的分布范围较广,肋蜷科和盖螺科种类分布范围狭窄,多数种类仅存在于单个水系,蚌科种类分布最为集中,以鄱阳湖和洞庭湖的种类最为丰富,种类数分别为58种和45种。研究表明,金沙江下游（云贵高原湖泊）、鄱阳湖和洞庭湖软体动物物种多样性丰富,建议将其列为我国淡水软体动物急需关注和保护的热点地区。       

湘江中游江段软体动物的种类组成及其多样性

系统地调查了湘江中游江段软体动物的种类组成、分布、种群数量;借助多样性分析软件对14个生境的软体动物的物种丰富度指数（DMA）、Shannon-Wiener多样性指数（H′）、均匀度指数（Jsw）进行了计算;用Srensen相似性系数C对不同生境软体动物群落进行了系统聚类分析。研究结果表明,湘江中游计有软体动物53种,分别隶属于9科20属,其中腹足纲6科12属31种,主要是田螺科的种类;双壳纲3科8属22种,主要是蚌科的种类。湘江中游共有10个优势种、22个常见种、21个罕见种;14个生境的物种丰富度指数DMA的取值范围在6.4319~2.3183之间,Shannon-Wiener多样性指数H′的范围在3.3859~2.1834之间,均匀度指数Jsw在0.94808~0.82067之间。根据不同生境物种的相似性系数C进行系统聚类分析,14个生境的群落相似性系数在0.5236的水平时全部聚合在一起。探讨了湘江中游建坝对软体动物多样性的影响,并进一步分析了株洲市大桥采集点软体动物多样性最高的原因。     

长江流域淡水软体动物物种多样性及其分布格局简

研究以正式发表的淡水软体动物文献和部分未发表野外调查数据为基础资料,分析了长江流域淡水软体动物物种多样性及分布格局。长江流域已报道的软体动物有296种,隶属17科62属,其中有197种是中国特有种。田螺科、肋蜷科、盖螺科、椎实螺科和蚌科是长江流域软体动物的主要组成部分,这5科种类数之和达249种,占总数的84.1%。从总体上低海拔地区的软体动物物种数高于高海拔地区,而高海拔地区特有种所占的比例却高于低海拔地区。支流和湖泊的种类数接近,分别为202种和210种,远高于长江干流(31种)。各水系软体动物的种类数、特有种数及特有种比例明显不同,洞庭湖水系和鄱阳湖水系的多样性最高。聚类分析表明,长江流域软体动物的分布基本反映了流域内的地势特点,形成了高原、中低海拔山地和低海拔平原的分布格局。不同类群的物种其分布格局也不相同,田螺科和椎实螺科的分布范围较广,肋蜷科和盖螺科种类分布范围狭窄,多数种类仅存在于单个水系,蚌科种类分布最为集中,以鄱阳湖和洞庭湖的种类最为丰富,种类数分别为58种和45种。研究表明,金沙江下游(云贵高原湖泊)、鄱阳湖和洞庭湖软体动物物种多样性丰富,建议将其列为我国淡水软体动物急需关注和保护的热点地区。     

三江平原典型沼泽湿地螺类组成生态指示

螺类作为湿地的重要生物类群,对环境变化响应敏感,这使得螺类成为潜在的环境指示物种。为了研究中国东北沼泽湿地不同类型湿地螺类群落结构的差异以及螺类作为不同类型湿地指示物种的可能,在2014年9月和2015年5月对小叶章沼泽化草甸湿地、臌囊苔草湿地、毛苔草湿地、漂筏苔草湿地共17个采样点进行螺类样品采集。共采集到了螺类8科13属17种4452个。研究表明,螺类以扁卷螺科Planorbidae、椎实螺科Lymnaeidae、膀胱螺科Physidae为主;4种不同类型湿地螺的种类组成不同,这些螺类的种类组成与不同类型湿地的水深、植物类型组成等湿地特征是相对应。螺类的生物多样性指数(ShannonWiener指数和Marglef指数)在不同类型湿地之间也存在一定差异,筛选了指示螺类6种,无褶螺是小叶章沼泽化草甸的指示物种,小土蜗、半球多脉扁螺和虹蛹螺是臌囊苔草湿地的指示物种,琥珀螺是毛苔草湿地的指示物种,平盘螺是漂筏苔草湿地的指示物种,这表明了螺类是沼泽湿地类型的重要指示生物。也为螺类生物多样性资源的保护、恢复和生态评价提供科学依据和资料积累。     

携带肺吸虫尾蚴的淡水螺类一新属二新种记述

近年来我国肺吸虫病的防治工作深入开展,引起人们对于寄生虫病流行区的某些淡水螺类,特别是对一些微小螺类的注意。福建及湖南两省1976年分别进行肺吸虫病调查时所采获的,并已查到肺吸虫尾蚴的螺类,经我们分析鉴定为二新种,隶属于觿螺科拟小豆螺属(新属)及小豆螺属。兹分别叙述如下。     

重庆市两栖动物物种多样性研究及保护

1996～2005年对重庆直辖市36个县（区、市）进行野外调查采集,结合有关资料记载,重庆市共有两栖动物2目9科18属45种,其中有尾目6种,无尾目弧胸类（蟾类）12种、固胸类（蚌类）27种。建议加强对该市两栖动物物种多样性及其生境的保护,合理利用两栖动物资源。     

贵州洞穴淡水、陆生贝类区系及新种记述

首次报道了贵州省安龙县、贵阳市、独山县、荔波县、安顺市、开阳县、息烽县、盘县、兴义市、大方县、普定县等39个洞穴内不同生境的淡水、陆生贝类,经鉴定得淡水、陆生螺类共计71种,分隶于15科,36属,其中淡水螺类3科4属5种;陆生螺类66种,12科32属;1新种,即荔波双边凹螺Chamalycaeus libonensis sp.nov.附有种类名录,栖息环境及地理分布,并对洞穴中的淡水、陆生贝类区系组成进行了讨论,对新种进行了详细的描述,与近似种进行了比较。     

湘江中游江段螺类的种类组成及区系分析

报道了湘江中游江段螺类的调查结果,计有螺类31种(其中5种为湖南省新记录),分别隶属于腹足纲6科11属,其中主要是田螺科的种类.对它们的种类组成、区系、种群大小、分布与栖息环境的关系进行了分析,并讨论了城镇污水未经处理直接排放及修河拦坝对螺类生存环境的影响.     

色季拉山冬虫夏草适生地草甸地表节肢动物群落多样性

为了解冬虫夏草适生地地表节肢动物多样性水平,2009年和2010年连续采用陷阱法对色季拉山3类典型的冬虫夏草适生草甸(山坡草甸、林缘草甸和滩地草甸)进行了调查。物种累积曲线和种积丰度估值反映,采集抽样充分。标本由14目、62科、114种组成,3类生境的类群组成相似,但数量分布明显不同,山坡草甸、林缘草甸和滩地草甸的优势类群分别为拟步甲科、蚁科和鳞科。通过各生物多样性指数和物种-相对多度分布模型比较可知,滩地草甸的多样性、丰富度和均匀度均低于另外两种生境。分析推测,冬虫夏草适生地地表节肢动物多样性与微生境的热量条件和人为干扰紧密相关。     

甘肃河西走廓不同生境中鼠类群落结构初步研究

本文对河西走廓不同生境中鼠类群落的物种组成和多样性进行了初步研究,在6种生境中进行了定量调查和采集,共获13种标本,隶于6（亚）科9属,其中古北界种类占优势。多样性分析结果表明：6种生境的物种丰富度指数RMargaler在.6139-1.9689之间。Shannon-Wiener指数（H')为1.0695-1.5607,Pielou旨数（J')和Simpson指数（D）分别为0.7242-0.9735和0．2768－0．4683,不同生境的丰富种数量（N1)变化趋势与H'相似,而非常丰富种数量（N2）的变化趋势为：半莫荒灌丛生境＞山地草原生境＞戈壁荒漠生境＞农田生境＞森林生境＞山地半荒漠灌丛生境。降水对不同生境类型中鼠类群落物种组成和多样性起直接的限制作用,同时海拔和人类干扰也是影响的因素。     

GENETIC STRUCTURE OF COEXISTING SEXUAL AND CLONAL SUBPOPULATIONS IN A FRESHWATER SNAIL (POTAMOPYRGUS ANTIPODARUM)

We examined clonal diversity and the distribution of both clonal and sexual genotypes in a single population of freshwater snails (Potamopyrgus antipodarum) in which diploid sexual individuals and triploid parthenogens coexist. A genetic analysis of individuals from three habitat zones in Lake Alexandrina, New Zealand revealed extremely high clonal diversity: 165 genotypes among 605 clonal individuals. The frequency of triploid clonal individuals increased with increasing depth in the lake, and most of the individual clones were habitat specific, suggesting that differences among habitats are important in structuring the clonal subpopulation. There were also high levels of clonal diversity within habitats, suggesting frequent origins of habitat-specific clones. In contrast, diploid sexual individuals were proportionately more common in the shallow regions of the lake (where infection by trematode larvae is highest), and there was no significant spatial structure in the sexual subpopulation. We suggest that habitat specialization by clones, as well as parasite-mediated selection against common clones, are important factors affecting the structure of this mixed population of sexual and clonal snails.     

西湖水域外来生物福寿螺的种类鉴定及种群遗传多样性研究

为了解杭州西湖景区外来生物福寿螺的分布现状和群体遗传变异特征,研究详细调研了西湖景区福寿螺的分布现状,并针对连续六年采集的福寿螺样本开展了分子鉴定及种群遗传多样性研究.调查结果表明,西湖福寿螺集中发生在苏堤以西,其中西北部的西里湖、茅家埠、杭州花圃及岳湖水域的发生密度高,在西南部的乌龟潭、浴鹄湾等水域发生密度较低.在6...     

Variation in habitat connectivity generates positive correlations between species and genetic diversity in a metacommunity

An increasing number of studies are simultaneously investigating species diversity (SD) and genetic diversity (GD) in the same systems, looking for ‘species– genetic diversity correlations’ (SGDCs). From negative to positive SGDCs have been reported, but studies have generally not quantified the processes underlying these correlations. They were also mostly conducted at large biogeographical scales or in recently degraded habitats. Such correlations have not been looked for in natural networks of connected habitat fragments (metacommunities), and the underlying processes remain elusive in most systems. We investigated these issues by studying freshwater snails in a pond network in Guadeloupe (Lesser Antilles). We recorded SD and habitat characteristics in 232 ponds and assessed GD in 75 populations of two species. Strongly significant and positive SGDCs were detected in both species. Based on a decomposition of SGDC as a function of variance–covariance of habitat characteristics, we showed that connectivity (opportunity of water flow between a site and the nearest watershed during the rainy season) has the strongest contribution on SGDCs. More connective sites received both more alleles and more species through immigration resulting in both higher GD and higher SD. Other habitat characteristics did not contribute, or contributed negatively, to SGDCs. This is true of the desiccation frequency of ponds during the dry season, presumably because species markedly differ in their ability to tolerate desiccation. Our study shows that variation in environmental characteristics of habitat patches can promote SGDCs at metacommunity scale when the studied species respond homogeneously to these environmental characteristics.     

Distribution of fishes in the Río Guayalejo-Río Tamesí system and relationships with environmental factors in northeastern Mexico

A priority issue in ecology and biogeography is understanding the patterns in species diversity and the causal factors of their distribution, which allows the generation of information for conservation strategies. The longitudinal distribution of fishes and their relationships with environmental variables were studied in the Guayalejo-Río Tamesí system (northeastern Mexico) from February 2000 to July 2001. A total of 5918 fish were caught in 27 collections along an altitudinal gradient in the main river course, from high mountain (1500 masl) to coastal plain near Tampico. Forty-three native and five exotic species, belonging to 35 genera in 23 families, were identified. Cluster analyses identified four major fish habitats in the river system. A distinctive euryhaline marine fish habitat (1) occurs near the mouth with native and two exotic species. Two other habitats consist essentially of freshwater fish species that are distributed along the longitudinal gradient. One of these habitats (habitat 4) shows greater diversity, as per the Shannon index value, and also includes amphidromous fish, in addition to two exotic freshwater fish; the other (habitat 2) includes freshwater, euryhaline and three exotic species. The changes in the frequency of occurrence and the abundance of Gambusia vittata, Astyanax mexicanus, and Xiphophorus variatus contribute to explaining differences between these habitats. Another habitat (3) is represented by two sampling sites located near the mouth and consist of freshwater and euryhaline fish and three exotic cyprinids with broad salinity tolerance. The low abundance and richness of exotic species suggest little impact on native fish fauna in this river. The fish assemblage of the Guayalejo-Tamesí river system species changes along a longitudinal gradient with the addition, replacement and presence of indicator species. Upstream fish fauna is mostly composed of freshwater species, some of them generalists that inhabit the entire longitudinal gradient, others that are restricted to certain sites, and the remainder of species is an assemblage composed of a mixture of euryhaline freshwater and marine species near the mouth.     

Diversity of Central European urban biota: effects of human‐made habitat types on plants and land snails

Aim Urbanization is associated with strong changes in biodiversity, but the diversity of plant and animal assemblages varies among urban habitats. We studied effects of urban habitats on the diversity of vascular plants and land snails in 32 large cities. Location Central Europe, Belgium and the Netherlands. Methods The species composition of all vascular plants that had not been planted by humans, and all land snails, was recorded in seven 1‐ha plots within each city. Each plot contained one urban habitat type representing a different disturbance regime: historical city square, boulevard, residential area with compact building pattern, residential area with open building pattern, park, early successional and mid‐successional site. For each plot, we obtained temperature and precipitation data. The effects of climate and habitat types on species composition were quantified using ordination methods with an adjusted variation partitioning algorithm. Differences in species composition among urban habitats were described using statistically determined diagnostic species, and differences in alpha, beta and gamma diversity were quantified. Results A total of 1196 plant and 87 snail species were recorded. Habitat type explained higher proportions of the total variation in both plant and snail species composition (11.2 and 8.2%, respectively) than did climate (4.6 and 6.3%). For both taxa, the main differences in species composition were observed between strongly urbanized sites in city centres and early successional and mid‐successional sites. For vascular plants, the number of species was lowest in city squares and boulevards, and highest at successional sites and in residential areas with compact building patterns. Beta diversity of vascular plants calculated for the same habitat types among cities was highest for squares and successional sites. The number of snail species was lowest in city squares and at early successional sites, and highest at mid‐successional sites. The highest beta diversity of snail assemblages among cities was observed within the city square and early successional habitat types, and the lowest within residential area habitat types. Main conclusions Urban habitats differ notably in the diversity of their vascular plant flora and land snail fauna. Understanding the habitat‐related biodiversity patterns in urbanized landscapes will allow projections of future impacts of urban land‐use changes on the biota.     

温度对福寿螺生物学特性的影响及高低温适应机制研究进展

在全球气候变化背景下, 福寿螺在我国及全球进一步扩散。极强的生态耐受力及快速适应力是福寿螺能够在入侵地区迅速扩散的重要原因。其中, 环境温度对福寿螺的生存、生长、发育及繁殖至关重要, 是影响福寿螺分布、扩散及暴发的重要因素之一。文章在综述温度耐受范围的基础上, 总结了福寿螺高低温适应的生理生化及分子机制, 并对从温度适应性角度揭示入侵机制的研究前景进行展望。当前, 福寿螺温度适应的生理生化机制研究主要针对化合物以及相关酶活性变化开展, 分子机制研究主要集中在HSP基因的表达差异上。在染色体水平基因组完成测序的基础上, 福寿螺快速适应性进化的生理生态耐受性机制和表型可塑性机制有待深入开展。     

Habitat availability does not explain the species richness patterns of European lentic and lotic freshwater animals

Aim In Europe, the relationships between species richness and latitude differ for lentic (standing water) and lotic (running water) species. Freshwater animals are highly dependent on suitable habitat, and thus the distribution of available habitat should strongly influence large‐scale patterns of species richness. We tested whether habitat availability can account for the differences in species richness patterns between European lentic and lotic freshwater animals. Location Europe. Methods We compiled occurrence data of 1959 lentic and 2445 lotic species as well as data on the amount of lentic and lotic habitats across 25 pre‐defined biogeographical regions of European freshwaters. We used the range of elevation of each region as a proxy for habitat diversity. We investigated the relationships between species richness, habitat availability and habitat diversity with univariate and multiple regression analyses. Results Species richness increased with habitat availability for lentic species but not for lotic species. Species richness increased with elevational range for lotic species but decreased for lentic species. For both groups, neither habitat availability nor diversity could account for previously reported latitudinal patterns in species richness. For lotic species, richness declined with latitude, whereas there was no relationship between habitat availability and latitude. For lentic species, richness showed a hump‐shaped relationship with latitude, whereas available habitat increased with latitude. Main conclusions Habitat availability and diversity are poor predictors of species richness of the European freshwater fauna across large scales. Our results indicate that the distributions of European freshwater animals are probably not in equilibrium and may still be influenced by history, namely the recurrent European glaciations and possible differences in post‐glacial recolonization. The distributions of lentic species appear to be closer to equilibrium than those of lotic species. This lends further support to the hypothesis that lentic species have a higher propensity for dispersal than lotic species.     

How did this snail get here? Several dispersal vectors inferred for an aquatic invasive species

1. How species reach and persist in isolated habitats remains an open question in many cases, especially for rapidly spreading invasive species. This is particularly true for temporary freshwater ponds, which can be remote and may dry out annually, but may still harbour high biodiversity. Persistence in such habitats depends on recurrent colonisation or species survival capacity, and ponds therefore provide an ideal system to investigate dispersal and connectivity. 2. Here, we test the hypothesis that the wide distributions and invasive potential of aquatic snails is due to their ability to exploit several dispersal vectors in different landscapes. We explored the population structure of Physa acuta (recent synonyms: Haitia acuta, Physella acuta, Pulmonata: Gastropoda), an invasive aquatic snail originating from North America, but established in temporary ponds in Doñana National Park, southern Spain. In this area, snails face land barriers when attempting to colonise other suitable habitat. 3. Genetic analyses using six microsatellite loci from 271 snails in 21 sites indicated that (i) geographically and hydrologically isolated snail populations in the park were genetically similar to a large snail population in rice fields more than 15 km away; (ii) these isolated ponds showed an isolation‐by‐distance pattern. This pattern broke down, however, for those ponds visited frequently by large mammals such as cattle, deer and wild boar; (iii) snail populations were panmictic in flooded and hydrologically connected rice fields. 4. These results support the notion that aquatic snails disperse readily by direct water connections in the flooded rice fields, can be carried by waterbirds flying between the rice fields and the park and may disperse between ponds within the park by attaching to large mammals. 5. The potential for aquatic snails such as Physa acuta to exploit several dispersal vectors may contribute to their wide distribution on various continents and their success as invasive species. We suggest that the interaction between different dispersal vectors, their relation to specific habitats and consequences at different geographic scales should be considered both when attempting to control invasive freshwater species and when protecting endangered species.     

Hydroperiod,predators and the distribution of physid snails across the freshwater habitat gradient

1. Studies of species distributions across environmental gradients further our understanding of mechanisms regulating species diversity at the landscape scale. For some freshwater taxa the habitat gradient from small, shallow and temporary ponds to large, deep and permanent lakes has been shown to be an important environmental axis. Freshwater snails are key players in freshwater ecosystems, but there are no comprehensive studies of their distributions across the entire freshwater habitat gradient. Here we test the hypothesis that snail species in the family Physidae are distributed in a non‐random manner across the habitat gradient. We sampled the snails, their predators and the abiotic environment of 61 ponds and lakes, spanning a wide range in depth and hydroperiod. 2. Temporary habitats had the lowest biomass of predators. Shallow permanent ponds had the highest biomass of invertebrate predators but an intermediate fish biomass. Deep ponds and lakes had the highest fish biomass and intermediate invertebrate biomass. Five species of physids occurred in the regional species pool and 60 of the 61 ponds and lakes surveyed contained physid snails. Each pond and lake contained an average of just 1.2 physid species, illustrating limited membership in local communities and substantial among‐site heterogeneity in species composition. 3. Physids showed strong sorting along the habitat gradient, with Physa vernalis found in the shortest hydroperiod ponds and Aplexa elongata, P. gyrina, P. acuta and P. ancillaria found in habitats of successively greater permanence. When organised into a site‐by‐species incidence matrix with sites ordered according to their hydroperiods, we found the pattern of incidence to be highly coherent, showing that much of the heterogeneity in species composition from one pond to another is explained by hydroperiod. We also found that the number of species replacements along this gradient was higher than random, showing that replacement is more important than nesting in describing species composition in ponds of different hydroperiod. 4. Discriminant analysis showed that pond depth, invertebrate biomass and fish biomass were the best predictors of species composition. Analysis of these niche dimensions showed that P. vernalis and A. elongata were most successful in shallow, temporary ponds with few predators. P. gyrina and P. acuta were typically found in ponds of intermediate depth and high predator abundance. P. ancillaria was found in the deepest lakes, which had abundant fish predators but few invertebrate predators. Of the five species considered, P. ancillaria, P. vernalis and A. elongata were relatively specialised with regard to key habitat characteristics, P. gyrina was moderately generalised and P. acuta was remarkably generalised, since it alone occurred across the entire freshwater habitat gradient. The exceptional habitat breadth of P. acuta stands in contrast to distributional studies of other freshwater taxa and deserves further attention.     

Diversity and Biotic Homogenization of Urban Land-Snail Faunas in Relation to Habitat Types and Macroclimate in 32 Central European Cities

The effects of non-native species invasions on community diversity and biotic homogenization have been described for various taxa in urban environments, but not for land snails. Here we relate the diversity of native and non-native land-snail urban faunas to urban habitat types and macroclimate, and analyse homogenization effects of non-native species across cities and within the main urban habitat types. Land-snail species were recorded in seven 1-ha plots in 32 cities of ten countries of Central Europe and Benelux (224 plots in total). Each plot represented one urban habitat type characterized by different management and a specific disturbance regime. For each plot, we obtained January, July and mean annual temperature and annual precipitation. Snail species were classified into either native or non-native. The effects of habitat type and macroclimate on the number of native and non-native species were analysed using generalized estimating equations; the homogenization effect of non-native species based on the Jaccard similarity index and homogenization index. We recorded 67 native and 20 non-native species. Besides being more numerous, native species also had much higher beta diversity than non-natives. There were significant differences between the studied habitat types in the numbers of native and non-native species, both of which decreased from less to heavily urbanized habitats. Macroclimate was more important for the number of non-native than native species; however in both cases the effect of climate on diversity was overridden by the effect of urban habitat type. This is the first study on urban land snails documenting that non-native land-snail species significantly contribute to homogenization among whole cities, but both the homogenization and diversification effects occur when individual habitat types are compared among cities. This indicates that the spread of non-native snail species may cause biotic homogenization, but it depends on scale and habitat type.