Identifying appropriate sampling and modelling approaches for analysing distributional patterns of Antarctic terrestrial arthropods along the Victoria Land latitudinal gradient

Biotic communities in Antarctic terrestrial ecosystems are relatively simple and often lack higher trophic levels (e. g. predators); thus, it is often assumed that species' distributions are mainly affected by abiotic factors such as climatic conditions, which change with increasing latitude, altitude and/or distance from the coast. However, it is becoming increasingly apparent that factors other than geographical gradients affect the distribution of organisms with low dispersal capability such as the terrestrial arthropods. In Victoria Land (East Antarctica) the distribution of springtail (Collembola) and mite (Acari) species vary at scales that range from a few square centimetres to regional and continental. Different species show different scales of variation that relate to factors such as local geological and glaciological history, and biotic interactions, but only weakly with latitudinal/altitudinal gradients. Here, we review the relevant literature and outline more appropriate sampling designs as well as suitable modelling techniques (e. g. linear mixed models and eigenvector mapping), that will more adequately address and identify the range of factors responsible for the distribution of terrestrial arthropods in Antarctica.

Large-scale spatial patterns in the distribution of Collembola (Hexapoda) species in Antarctic terrestrial ecosystems

We tested whether the distribution of three common springtail species (Gressittacantha terranova, Gomphiocephalus hodgsoni and Friesea grisea) in Victoria Land (Antarctica) could be modelled as a function of latitude, longitude, altitude and distance from the sea.

Victoria Land, Ross Dependency, Antarctica.

Generalized linear models were constructed using species presence/absence data relative to geographical features (latitude, longitude, altitude, distance from sea) across the species' entire ranges. Model results were then integrated with the known phylogeography of each species and hypotheses were generated on the role of climate as a major driver of Antarctic springtail distribution.

Based on model selection using Akaike's information criterion, the species' distributions were: hump-shaped relative to longitude and monotonic with altitude for Gressittacantha terranova; hump-shaped relative to latitude and monotonic with altitude for Gomphiocephalus hodgsoni; and hump-shaped relative to longitude and monotonic with latitude, altitude and distance from the sea for Friesea grisea.

No single distributional pattern was shared by the three species. While distributions were partially a response to climatic spatial clines, the patterns observed strongly suggest that past geological events have influenced the observed distributions. Accordingly, present-day spatial patterns are likely to have arisen from the interaction of historical and environmental drivers. Future studies will need to integrate a range of spatial and temporal scales to further quantify their respective roles.

Modelling local-scale determinants and the probability of microarthropod species occurrence in Antarctic soils

Soil fauna in the extreme conditions of Antarctica consists of a few microinvertebrate species patchily distributed at different spatial scales. Populations of the prostigmatic mite Stereotydeus belli and the collembolan Gressittacantha terranova from northern Victoria Land (Antarctica) were used as models to study the effect of soil properties on microarthropod distributions. In agreement with the general assumption that the development and distribution of life in these ecosystems is mainly controlled by abiotic factors, we found that the probability of occurrence of S. belli depends on soil moisture and texture and on the sampling period (which affects the general availability of water); surprisingly, none of the analysed variables were significantly related to the G. terranova distribution. Based on our results and literature data, we propose a theoretical model that introduces biotic interactions among the major factors driving the local distribution of collembolans in Antarctic terrestrial ecosystems. (c) 2007 Elsevier Ltd. All rights reserved.

Towards a population ecology of stressed environments: the effects of zinc on the springtail Folsomia candida

1. To understand population dynamics in stressed environments it is necessary to join together two classical lines of research. Population responses to environmental stress have been studied at low density in life table response experiments. These show how the population's growth rate (pgr) at low density varies in relation to levels of stress. Population responses to density, on the other hand, are based on examination of the relationship between pgr and population density. 2. The joint effects of stress and density on pgr can be pictured as a contour map in which pgr varies with stress and density in the same way that the height of land above sea level varies with latitude and longitude. Here a microcosm experiment is reported that compared the joint effects of zinc and population density on the pgr of the springtail Folsomia candida (Collembola). 3. Our experiments allowed the plotting of a complete map of the effects of density and a stressor on pgr. Particularly important was the position of the pgr= 0 contour, which suggested that carrying capacity varied little with zinc concentration until toxic levels were reached. 4. This prediction accords well with observations of population abundance in the field. The method also allowed us to demonstrate, simultaneously, hormesis, toxicity, an Allee effect and density dependence. 5. The mechanisms responsible for these phenomena are discussed. As zinc is an essential trace element the initial increase in pgr is probably a consequence of dietary zinc deficiency. The Allee effect may be attributed to productivity of the environment increasing with density at low density. Density dependence is a result of food limitation. 6. Synthesis and applications. We illustrate a novel solution based on mapping a population's growth rate in relation to stress and population density. Our method allows us to demonstrate, simultaneously, hormesis, toxicity, an Allee effect and density dependence in an important ecological indicator species. We hope that the approach followed here will prove to have general applicability enabling predictions of field abundance to be made from estimates of the joint effects of the stressors and density on population growth rate.

Cytogenetics, morphology and evolution of four subspecies of the Giant Sheep argali (Ovis ammon) of Asia

Dalai-lamae (Ovis ammon dalai-lamae), Gobi (O. a. darwini), Kara Tau (O. a. nigrimontana) and Tibetan (O. a. hodgsoni) argali share a 2n = 56 diploid chromosome number and a karyotype consisting of 2 pairs of biarmed and 25 pairs of acrocentric autosomes, a large acrocentric X and a minute Y chromosome. The Giemsa-banding patterns of the largest pair of biarmed chromosomes were identical to those of the largest biarmed chromosomes in all wild sheep and domestic sheep of the genus Ovis. The banding patterns of the second pair of biarmed chromosomes (metacentric) were identical to the third pair of biarmed chromosomes in Ovis with 2n = 54 and to the third largest pair of chromosomes in the 2n = 52 karyotype of Siberian snow sheep (O. nivicola). The G-banded karyotypes of dalai-lamae, darwini, hodgsoni and nigrimontana are consistent with all subspecies of argali (O. ammon), except that the Y chromosome is acrocentric instead of metacentric as typical of the argaliform wild sheep and Ovis. The Dalai-lamae and Tibetan argali specimens exhibit the light-colored, long-haired ruffs and body coloration typical of argalis from the Tibetan Plateau. The Gobi argali, from the extreme western Gobi, is similar to the dark phase argali.

Mitochondrial control region sequence variation within the argali wild sheep (Ovis ammon): evolution and conservation relevance

The phylogenetic relationship of several subspecies of Ovis ammon were analyzed by comparing DNA sequences within the entire mitochondrial D-loop region. Five putative subspecies of ammon (dalai-lamae, darwini, hodgsoni, sairensis and adamerzi) were sampled from four provinces in China [Xinjiang, Qinghai, Gansu and Xizang (Tibet)] and two (servertzovi and nigrimontana) from Uzbekistan. The argalis sampled represent most of the currently recognized putative Subspecies of argali. Analysis of mtDNA sequences revealed high variability within ammon (7.7%), ranging from 2.4 to 11.5%. MaxiMUM-Parsimony tree indicated that nigrimontana from Uzbekistan diverged First, followed by severtzovi from Uzbekistan. The dispersal of argalis into China gave rise to three clades, suggesting that the argali originated in Western Asia and then dispersed throughout the central Asian highlands on a southeastward course. Among the Chinese argalis, mtDNA analysis places dalailamae genetically closer to hodgsoni than to darwini. Severtzovi and.. nigrimontana are two separate subspecies and genetically distinct from the Chinese argali.

藏羚羊冷季对干物质的消化效率

藏羚羊(Pantholops hodgsoni)为青藏高原特有物种,也是世界上最为珍贵和稀有的物种之一.作为青藏高原野生食草动物的典型代表,藏羚羊种群也是构成青藏高原自然生态系统极为重要的组成部分

藏羚寄生蠕虫卵粪检调查初报

2004年12月25日-2005年1月5日对位于青藏公路楚玛尔河大桥附近集群的藏羚（Pantholops hodgsoni），随机拣取其新鲜粪便共计36份带回实验室。利用漂浮法、沉淀法对粪样进行寄生虫蠕虫卵检查，结果显示，粪样中存在有细颈属（Nematodirus）、马歇尔属（Marshallagia）线虫卵和莫尼茨属（Moniezia）绦虫卵，其感染率在19．4％-94．4％之间，感染强度（EPG）分别为5．58、5．11和2．86。结果表明，冬季藏羚的寄生蠕虫感染率高，但感染种类少和感染强度低。

可可西里地区藏羚的社群特征

藏羚(Pantholops hodgsoni)的集群类型有雌性群、雄性群、母仔群、雌雄混群和独羚5种形式。2002年7月～2003年12月，在可可西里地区沿青藏公路设立试验区，直接观察到936群次，计13795只次藏羚。藏羚的集群类型受到生育周期的影响，季节间差异显著。春季以雌性群(60．49％)和雄性群(30．86％)为主；夏季和秋季主要为雌性群(41．65％，49．66％)和母仔群(49．36％，33．67％)；雌雄混群(58．14％)主要出现在冬季。雄性群在1年中很少见，尤其是夏秋两季，冬季较为常见，多由亚成体雄性组成。独羚是一种特殊的集群类型，占11．32％。常见的集群大小为2～20只，占71．90％，其次是21～200只的群，占16．35％；>200只的集群极少，仅占0．43％，且仅出现于夏季产羔往返迁徙途中。藏羚的集群大小受竞争、捕食风险以及迁徙繁殖的共同影响。藏羚的集群极不稳定，交配期雌雄混合群受雄性亚成体的干扰经常改变，而在迁徙季节大群和小群之间的转换也很频繁。大型集群为雌性群或母仔群，其最适集群大小为2～20只。

爱羚：第一只家养成功的藏羚

藏羚(Pantholops hodgsoni)是青藏高原特有物种，隶属于偶蹄木牛科山羊亚科藏羚属~（[1-4]），主要分布于中国境内的青海、西藏、新疆三省区交界处的高寒荒漠化草原、高寒草原和高寒草甸地区，海拔一般在4 100-5 00m之间，生存环境十分恶劣，目前已处于濒危状态。国际社会对藏羚羊的保护高度关注，但由于缺乏对该物种的科学认识，保护措施只能以反盗猎和打击藏羚羊绒及其制品的走私贸易为主~（[4]）。我们在青海省重大科技攻关项目和中国科学院知识创新工程项目的资助下，开展了藏羚羊种群生物学及保护措施的研究，并于2002年7月至12月先后3次在可可西里国家级自然保护区进行考察，发现保护区救护的1只名叫爱羚的雄性藏羚在人工饲养条件下生长良好，已达到性成熟状态。该结果意味着人工驯养可能性在藏羚的保护实践中发挥重要作用。现将考察报告如下。

Group size effects on foraging and vigilance in migratory Tibetan antelope

Large group sizes have been hypothesized to decrease predation risk and increase food competition. We investigated group size effects on vigilance and foraging behaviour during the migratory period in female Tibetan antelope Pantholops hodgsoni, in the Kekexili Nature Reserve of Qinghai Province, China. During June to August, adult female antelope and yearling females gather in large migratory groups and cross the Qinghai-Tibet highway to calving grounds within the Nature Reserve and return to Qumalai county after calving. Large groups of antelope aggregate in the migratory corridor where they compete for limited food resources and attract the attention of mammalian and avian predators and scavengers. We restricted our sampling to groups of less than 30 antelopes and thus limit our inference accordingly. Focal-animal sampling was used to record the behaviour of the free-ranging antelope except for those with lambs. Tibetan antelope spent more time foraging in larger groups but frequency of foraging bouts was not affected by group size. Conversely, the time spent vigilant and frequency of vigilance bouts decreased with increased group size. We suggest that these results are best explained by competition for food and risk of predation. (C) 2007 Elsevier B.V. All rights reserved.

基于GIS探讨人类活动和坡度对藏羚生境的影响

以3S技术为手段，研究了藏羚在青海最主要分布区曲麻莱、治多和可可西里境内藏羚生境状况及其坡度、道路、和居民点对藏羚生境的影响。通过野外考察基本掌握了藏羚的生境的基本特征，取得了考察路线附近区域内藏羚分布的GPS数据及其具有对应的数量、地形地貌、生境类型、人类活动状况等属性数据的藏羚分布点图层。对研究地区LANDSAT TM / ETM+ 5（红）、4（绿）、3（蓝）波段组合影像进行非监督分类，共分出水体和裸岩、沼泽地、沙地、砾石地、低草地、中草地和高草地7种生境类型，将藏羚生境适宜等级划分为不适宜、较差、适宜和非常适宜，其中适宜等级和非常适宜等级的生境类型为藏羚适宜的生境。 首先，将藏羚分布点图层分别和遥感影像假彩色合成图像、坡度图层、道路图层、居民点图层进行叠加分析、距离查询等分析了遥感影像非监督分类的判图依据，设立了坡度、道路、居民点对藏羚生境影响强度的评价原则。然后，通过对研究地区遥感影像进行非监督分类分析研究了藏羚不同适宜程度的生境面积。通过坡度分析和地图查询分析研究了坡度对藏羚生境的影响。通过缓冲区分析研究了道路和居民点对藏羚生境的影响。最后将坡度、道路和居民点三个因素结合起来通过地图综合查询分析研究了这三个因素对藏羚生境的综合影响，并给出了研究地区藏羚不同适宜等级的生境面积。 主要的研究结果和结论如下： 1、从不同类型生境在研究地区中所占比例的趋势上看，治多地区和曲麻莱地区的植被要明显优于可可西里地区，这与整个研究地区从西北到东南地势逐渐降低、水热条件逐渐变好的趋势相一致，至少可以说，从食物条件来看，治多地区和曲麻莱地区比可可西里地区更适于藏羚的栖息。 在曲麻莱地区藏羚的潜在生境面积共26861 km2，占该地区总面积的69%；在治多地区藏羚的潜在生境面积共21617 km2，占该地区总面积的68%；在可可西里地区藏羚的潜在生境面积共26398 km2，占该地区总面积的54%。 2、根据藏羚分布点图层与坡度分析图层的地图查询分析，把藏羚的生境按坡度分为2类，坡度小于等于30度时为适宜生境，坡度大于30度时为不适宜生境。将研究地区坡度栅格图像（grid文件）和非监督分类结果栅格图像（grid文件）进行地图查询分析，结果表明，在整个研究地区坡度大于30度的生境面积所占的比例不到总面积的3%，坡度影响下研究地区藏羚适宜栖息的生境面积变化不大。考虑到坡度的影响，曲麻莱、治多和可可西里适合藏羚栖息的面积分别为26663 km2（68%）、21187 km2（66%）和26350 km2（54%）。 3、根据最近原则连接藏羚分布点图层与道路图层空间数据，通过Distance综合查询分析，把道路对藏羚的影响程度划分为4个等级：距离道路0－1000m，强烈影响；距离道路1000－2000m，中度影响；距离道路2000－3000m，轻度影响；距离道3000m以外，无影响。然后在ArcView GIS 3.2a软件环境的支持下对研究地区的道路图层分别做距离道路为1000m、2000m和3000m的缓冲区分析研究，则曲麻莱、治多和可可西里地区藏羚生境受道路累计影响的面积及其分别占各研究地区总面积的比例分别为20215 km2（51.80%）、19480 km2（61%）和4437 km2（9 %）。考虑道路对藏羚生境的影响，在治多和曲麻莱地区，由于道路的影响将使得藏羚生境大面积丧失，生境高度破碎化。 4、根据最近原则连接藏羚分布点图层与居民点图层空间数据，通过Distance综合查询分析，把居民点对藏羚的影响程度划分为4个等级：距离居民点0－3000m，强烈影响；距离居民点3000－6000m，中度影响；距离居民点6000－9000m，轻度影响；距离居民点9000m以外，无影响。然后在ArcView GIS 3.2a软件环境的支持下对研究地区的居民点图层分别做距离居民点距离为3000m、6000m和9000m的缓冲区分析。曲麻莱、治多和可可西里地区藏羚生境受居民点影响的面积及其分别占总面积的比例分别为11282 km2（29%）、15258 km2（48%）和3846 km2（8%）。从居民点对藏羚生境的影响看，由于居民点的影响使得治多和曲麻莱地区，尤其是治多地区，藏羚生境大面积丧失，生境高度破碎化。 5、人类活动（主要是道路和居民点）对藏羚生境适宜生境面积的影响是研究中主要的内容，鉴于道路和居民点对藏羚生境影响的评价原则分类方法一致，我们把道路和居民点对藏羚的影响程度合并为4个等级（距离道路0－1000m内或距离居民点0－3000m内，强烈影响；距离道路1000－2000m内或距离居民点3000－6000m内，中度影响；距离道路2000－3000m内或距离居民点6000－9000m内，轻度影响；距离道路3000m以外或距离居民点9000m以外，无影响，对道路和居民点相应距离的缓冲区分析图层进行合并等操作，测定曲麻莱、治多和可可西里地区藏羚生境受人类活动影响的面积及其占总面积的比例分别为21595 km2（55%）、22271 km2（70%）和4775 km2（10%）。 在治多和曲麻莱地区，由于人类活动的影响使得藏羚生境大面积丧失，生境高度破碎化，尤其是治多地区，影响面积达将近70%。在可可西里地区，10%的影响面积虽然不是太大，但是近几年来由于各种形式的旅游日趋升温，尤其是青藏铁路建设开通，将增加道路对藏羚生境的影响程度。人类活动影响在研究地区分布极不平均，在曲麻莱的中东部、治多的东部以及可可西里的109国道附近人类活动影响的强度较大，在这些地区藏羚的生存条件恶劣，甚至部分地区已经不适合藏羚栖息了。 6、最后，基于研究地区的坡度grid图层、非监督分类grid图层以及不同程度人类活动影响的grid图层，对不同坡度、道路和居民影响的生境面积进行综合查询分析。把人类活动对藏羚生境的影响强度重新划分为如下3个等级，A、短距离影响，距离道路1000m或距离居民点3000m范围内的影响，也就是人类活动的强烈影响；B、中距离影响，距离道路2000m或距离居民点6000m范围内的影响，也就是人类活动的强烈影响和中度影响之和；C、长距离影响，距离道路3000m或距离居民点9000m范围内的影响，也就是人类活动的强烈影响、中度影响和轻度影响的总和。曲麻莱、治多和可可西里研究地区中坡度小于等于30度并且人类活动长距离范围影响下藏羚适合栖息的生境面积及占相应研究地区总面积的比例为12597 km2（32%）、6117km2（19%）和23564km2（48%）。 在研究地区，治多地区人类活动对藏羚生境适宜性的影响最为严重，其次为曲麻莱地区，而可可西里地区的人类活动影响较小。尤其是治多地区和曲麻莱地区，当人类活动的影响最大距离时，治多地区藏羚适宜生境面积竟然不到总面积的1/5，曲麻莱地区不到1/3。这两地区人类活动主要集中在东部，导致治多东部地区和曲麻莱中东部地区几乎没有藏羚分布。于是，由于人类活动的影响，使得拥有良好生境条件的治多和曲麻莱地区适合藏羚栖息的生境却较少，而生境条件相对较差的可可西里地区反而拥有相对较多的适合藏羚栖息的生境。

Morphologie évolutive et fonctionnelle des hémichordés

L’embranchement Hemichordata regroupe les classes Enteropneusta et Pterobranchia. Hemichordata constitue, avec l’embranchement Echinodermata, le groupe-frère des chordés. Les entéropneustes sont des organismes vermiformes solitaires qui vivent sous ou à la surface du substrat et s’alimentent généralement par déposivorie, alors que les ptérobranches sont des organismes coloniaux filtreurs habitant dans un réseau de tubes appelé coenecium. Ce mémoire présente trois études dont le point commun est l’utilisation des hémichordés actuels pour répondre à des questions concernant l’évolution des hémichordés, des chordés, et du super-embranchement qui les regroupe, Deuterostomia. Notre première étude démontre que les fentes pharyngiennes, l’organe pré-oral cilié (POCO) et le pharynx de l’entéropneuste Protoglossus graveolens sont utilisés pour l’alimentation par filtration. Le système de filtration de P. graveolens permet la capture de particules jusqu’à 1.3 um, à un débit de 4.05 mm.s-1, pour une demande énergétique de 0.009 uW. Les similarités structurales et fonctionnelles avec le système de filtration des céphalochordés suggèrent que la filtration pharyngienne est ancestrale aux deutérostomes. Lors de notre deuxième étude, nous avons exploré l’hypothèse selon laquelle le POCO des entéropneustes, une structure ciliée pré-buccale au rôle possiblement chémorécepteur, serait homologue au « wheel organ » des céphalochordés et à l’adénohypophyse des vertébrés. Pour cela, nous avons déterminé par immunohistochimie l’expression de Pit-1, un facteur de transcription spécifique à ces deux structures, chez l’entéropneuste Saccoglossus pusillus. Pit-1 est exprimé dans des cellules sensorielles du POCO, mais aussi dans des cellules épithéliales distribuées dans le proboscis, collet et tronc. Ce patron d’expression ne permet pas de confirmer ou rejeter l’homologie du POCO et de l’adénohypophyse des vertébrés. Lors de notre troisième étude, nous avons caractérisé l’ultrastructure du coenecium des ptérobranches Cephalodiscus hodgsoni, Cephalodiscus nigrescens et Cephalodiscus densus par microscopie électronique à transmisison et à balayage. Cephalodiscus est le groupe frère de Graptolithina, un groupe qui inclut les graptolithes éteints ainsi que les ptérobranches du genre Rhabdopleura. Nous avons décrit les types de fibrilles de collagène présents, leur taille et leur organisation, ainsi que l’organisation globale du coenecium. Nous avons ainsi démontré la présence chez Cephalodiscus d’une organisation similaire au paracortex, pseudocortex et eucortex des graptolithes. La présence chez Cephalodiscus de ce type d’organisation suggère que le cortex est ancestral à la classe Pterobranchia. Ces trois études illustrent plusieurs axes importants de la recherche sur les hémichordés, qui en intégrant des données morphologiques, fonctionnelles et moléculaires permet de reconstruire certains évènements clés de l’évolution des deutérostomes.

Biodiversity of Collembola in urban soils and the use of Folsomia candida to assess soil 'quality'

The effects of metal contamination on natural populations of Collembola in soils from five sites in the Wolverhampton area ( West Midlands, England) were examined. Analysis revealed that metal concentrations were elevated above background levels at all sites. One location in particular (Ladymoor, a former smelting site) was highly contaminated with Cd, Cu, Pb and Zn at more than 20 times background levels. Biodiversity indices ( Shannon - Weiner, Simpson index, Margalef index, alpha index, species richness, Shaneven ( evenness) and Berger - Parker dominance) were calculated. Of these indices, estimates of species richness and evenness were most effective at highlighting the differences between the Collembola communities. Indeed, the highest number of species were found at the most contaminated site, although the Collembola population also had a comparatively low evenness value, with just two species dominating. The number of individuals per species were allocated into geometric classes and plotted against the cumulative number of species as a percentage. At Ladymoor, there were more geometric classes, and the slope of the line was shallower than at the other four sites. This characteristic is a feature of polluted sites, where a few species are dominant and most species are rare. The Ladymoor soil also had a dominance of Isotomurus palustris, and was the only site in which Ceratophysella denticulata was found. Previous studies have shown that these two species are often found in sites subject to high metal contamination. Survival and reproduction of the "standard'' test springtail, Folsomia candida (Willem), were determined in a 4 week exposure test to soils from all five sites. Mortality was significantly increased in adults and reproduction significantly lower in the Ladymoor soil in comparison to the other four sites. This study has shown that severe metal contamination can be related to the population structure of Collembola in the field, and performance of F. candida ( in soils from such sites) in the laboratory.

A comparative study of the effects of metal contamination on collembola in the field and in the laboratory

We examined the species diversity and abundance of Collembola at 32 sampling points along a gradient of metal contamination in a rough grassland site ( Wolverhampton, England), formerly used for the disposal of metal-rich smelting waste. Differences in the concentrations of Cd, Cu, Pb and Zn between the least and most contaminated part of the 35 metre transect were more than one order of magnitude. A gradient of Zn concentrations from 597 to 9080 mug g(-1) dry soil was found. A comparison between field concentrations of the four metals and previous studies on their relative toxicities to Collembola, suggested that Zn is likely to be responsible for any ecotoxicological effects on springtails at this site. Euedaphic ( soil dwelling) Collembola were extracted by placing soil cores into Tullgren funnels and epedaphic ( surface dwelling) species were sampled using pitfall traps. There was no obvious relationship between the total abundance, or a range of commonly used diversity indices, and Zn levels in soils. However, individual species showed considerable differences in abundance. Metal "tolerant'' (e.g., Ceratophysella denticulata) and metal "sensitive'' (e.g., Cryptopygus thermophilus) species could be identified. Epedaphic species appeared to be influenced less by metal contamination than euedaphic species. This difference is probably due to the higher mobility and lower contact with the soil pore water of epedaphic springtails in comparison to euedaphic Collembola. In an experiment exposing the standard test springtail, Folsomia candida, to soils from all 32 sampling points, adult survival and reproduction showed small but significant negative relationships with total Zn concentrations. Nevertheless, juveniles were still produced from eggs laid by females in the most contaminated soils with 9080 mug g(-1) Zn. Folsomia candida is much more sensitive to equivalent concentrations of Zn in the standard OECD soil. Thus, care should be taken in extrapolating the results of laboratory toxicity tests on metals in OECD soil to field soils, in which, the biological availability of contaminants is likely to be lower. Our studies have shown the importance of ecotoxicological effects at the species level. Although there may be no differences in overall abundance, sensitive species that are numerous in contaminated sites, and which may play important roles in decomposition("keystone species'') can be greatly reduced in numbers by pollution.