Ravines as refuges for Orchidaceae in south‐eastern Mexico

Floristic studies of south‐eastern Mexico have not considered the ravine component of the landscape and, in this study, we demonstrate the potential of ravines as refuges for orchids. At elevations of 1442–2358 m in the buffer zone of the Tacaná Volcano Biosphere Reserve, in the region of Soconusco, south‐eastern Mexico, where 7.68% of the landscape has slopes > 45°, we registered 86 species of orchid from 35 genera, 14 (16.25%) of which were exclusive to ravines, 47 (54.6%) were exclusive to accessible surrounding areas and 25 (29%) colonized both types of habitat. The tropical mountain cloud forest (TMCF) ecosystem was distributed in the accessible areas surrounding the ravines and in some sites extended into the ravines themselves. Evergreen mountain scrub forest (EMSF), only found in the ravines, contributed eight species of orchid exclusive to this ecosystem. The elevation, orientation and slope of the ravines influenced species richness. The instability of the ‘soils’ on steep slopes and occasional landslides were negative environmental characteristics of the ravines, which, however, were mostly dependent on the management of surrounding areas, and epiphytes inhabiting ravines and the surrounding areas shared similar risks of whole‐tree and branch fall, wind and torrential rain. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 283–297.     

Effects of recreation areas on avian communities in coastal New South Wales' parks

Summary Information on the impacts of outdoor recreation on wildlife within national parks and reserves can be useful to natural area managers. This study aimed to (i) investigate the density, diversity and species composition of avian communities in recreation areas in bushland settings in comparison to surrounding natural habitats, and (ii) determine the influence of the presence of people on avian assemblages in such recreation areas. Avian density, species richness and community composition were compared between six high‐visitation bushland camping and picnic areas (recreation areas) and surrounding undisturbed habitats to examine the effect of recreation areas on avian assemblages. While total numbers of birds detected was found to be higher in recreation areas, species richness trends indicated that a greater diversity of birds was associated with the surrounding natural habitats, which were found to support a taxonomically different avian assemblage to the recreation areas. Interestingly, species previously shown to distinguish urban avian communities were commonly present and often more abundant in the recreation areas than the surrounding natural habitats. We investigated the effect of the intermittent presence of people (rather than clearing alone) and addressed changes in the diurnal distribution of species, by comparing avian assemblages at 22 picnic areas in the morning, at midday and in the afternoon between days of high and low human visitation. Observations of the availability of anthropogenic food resources and subsequent utilization by avifauna were recorded. Generally, avian assemblages appeared to be independent of the presence of people, although the provision of anthropogenic foods is thought to have the potential to adversely affect individual birds. The findings of this study suggest that even small‐scale habitat clearance to create picnic areas adversely affects the avian assemblage present, with temporal changes in visitation levels of humans in these areas appearing to have had no additional influence unless through indirect impacts from anthropogenic foods.     

Why is the Cape Peninsula so rich in plant species? An analysis of the independent diversity components

With 2285 species of higher plants crammed into 471 km², the flora of South Africa's Cape Peninsula is exceptionally rich. Similar sized areas in other Mediterranean-climate region biodiversity hot-spots support between 4.7 and 2.7 times fewer species. The high plant species richness of the Cape Peninsula is due to the exceptionally high turnover between moderately species-rich sites in different habitats (beta diversity) and between sites in similar habitats along geographical gradients (gamma diversity). Highest beta diversity, encompassing almost complete turnover, was recorded along soil fertility gradients. Although similar patterns for these independent components explain the richness of other regions in the Cape Floristic Region, it is the very long and steep habitat gradients of the Cape Peninsula that makes this region exceptionally rich. Furthermore, the flora is characterized by a high degree of rarity, a phenomenon that undoubtedly influences the turnover. Future research should focus on developing a biological and ecological understanding of the different forms of rarity and integrating this into management plans for the maintenance of biodiversity.     

洞庭湖区鼠类群落的物种多样性分析

通过对洞庭湖区黑线姬鼠褐家鼠主害区桃源的害鼠群落调查,揭示了平原农田生态类型区、丘陵农林复合生态类型区和山区林农复合生态类型区及其不同生境的鼠类群落的物种多样性。在人类干扰程度最高的平原生态类型区,鼠类群落的优势种突出,优势集中性指数最高,丘陵生态区次之,而具有大片森林、受干扰较低的山区林农复合生态区,优势集中性指数最低。物种多样性Shannon—Weiner指数和均匀性指数亦显示同样的规律：适度干扰的山区复合生态区的多样性指数最高,均匀性最好,丘陵生态区居中,平原生态区最低。不论何种生态类型区,农田生境鼠类群落的优势种都较突出,优势集中性指数也较高,群落多样性和均匀性较低;林地生境的优势集中性有较大下降,山区林地内的鼠种比丘陵区要多,优势集中性指数也较低,多样性指数和均匀度都有提高。林缘农田在同一生态类型不同生境内优势集中性最低、多样性指数和均匀性最高。比较不同生境鼠类群落的相似性,最不相似的群落是农田与受人类干扰较小的森林。这些现象说明人类的社会生产活动使害鼠群落的物种多样性降低、优势度下降、优势种突出、均匀性降低,形成了只利于少数几个种群栖息和生产发展的环境,最终导致少数种群的暴发,形成危害。但适度干扰能提高物种多样性。     

Orchid biogeography and factors associated with rarity in a biodiversity hotspot,the Southwest Australian Floristic Region

Aim The causes of orchid diversification and intrinsic rarity are poorly resolved. The Orchidaceae of the Southwest Australian Floristic Region use a diversity of pollination strategies and sites of mycorrhizal infection, and occupy a diversity of habitats. We combined a biogeographic analysis with analysis of factors associated with rarity to establish: (1) the landscape features correlated with taxon turnover and speciation, and (2) the possible role in taxon rarity of geographic region, pollination strategy, edaphic habitat and site of mycorrhizal infection. Location Southwest Australian Floristic Region. Methods The distributions of 407 orchid taxa (species and subspecies) were mapped at the quarter‐degree scale using 13,267 collections in the Western Australian Herbarium. This database was used to map taxon richness, for a biogeographic analysis and to quantify rarity of taxa. Using herbarium records, rarity was expressed as mean abundance, mean distribution and incidence of rarity based on abundance and distribution for each genus. We tested for differences in rarity of species between pollination strategies, edaphic habitats and sites of mycorrhizal infection. Results Taxon richness was highest in the High Rainfall Province. Biogeographic provincial boundaries for orchids were aligned with rainfall, while district boundaries tended to follow geological formations. When rarity was defined as either low abundance or small distribution, the greatest number of rare taxa occurred in areas of high taxon richness and naturally fragmented edaphic environments. For both abundance and distributional extent, sexual deception had a significantly higher incidence of rarity than food‐rewarding taxa. There was no significant difference in rarity with site of mycorrhizal infection. Main conclusions While large‐scale edaphic and climatic variation are correlated with orchid taxon turnover and speciation in a similar fashion to the flora in general, the processes responsible for patterns of diversity may differ. Fragmented edaphic environments appear to be associated with a higher incidence of rare species due to limited dispersal/colonization opportunities or radiations of taxa in allopatry. The high incidence of rarity in sexually deceptive taxa could be due to either low fruit set or the risk of specializing on a single pollinator species.     

Land use influences harvestman diversity in northern Spain: a case study involving secondary grasslands and forest plantations (Arachnida: Opiliones)

Harvestmen have a general distribution pattern with more species and higher abundance in forests than in open habitats, as previously verified in mountain Cantabrian areas of northern Spain, of the Orocantabrian Province. The study of harvestmen of the low Cantabrian areas of the adjacent biogeographic Cantabro-Atlantic Province is highly appropriate to determine the influence of biogeographic position on the main diversity parameters and the effect of different land uses on harvestman assemblages. The main types of managed habitats (forest plantations and secondary grasslands), together with natural forests, non-planted young forests, shrublands and habitat boundaries were continuously sampled with seven pitfall traps during 1 year at 28 sites. The harvestman assemblages were classified using six different analyses, and indicator species were identified. The spatial patterns of harvestman diversity in low areas differed from those of mountain areas, although they have 15 species in common. Remarkably, higher average harvestman species richness was measured in low Cantabrian areas than in mountain areas. Shrublands and boundaries were the most species-rich habitats. Forested areas were the poorest in abundance, and were not the habitats richest in harvestman species, though they had higher average richness than mountain Cantabrian forests. Grasslands had a unique harvestman composition with significant extraordinary abundances, in particular of Homalenotus quadridentatus (indicator species of this habitat) and H. laranderas. Interestingly, H. laranderas, Paroligolophus agrestis and Ischyropsalis hispanica, indicator species of some open habitats in low Cantabrian areas, have recently been shown to be indicators of shady forests in mountain Cantabrian territories.     

Colonization of dynamic Mediterranean landscapes: where do birds come from after fire?

Aim Two main mechanisms may explain post‐disturbance species colonization patterns of early successional habitats such as those originated by wildfires. First, post‐disturbance colonization is not limited by the dispersal ability of the species to reach the newly created open areas and, secondly, colonization is limited by dispersal. Under the first hypothesis, we expect, at a regional scale, to find similar post‐disturbance communities to develop on recently burned sites. However, colonization limited by dispersal will lead to strong between‐site variations in species composition. Location To test these hypotheses, we studied the post‐fire colonization patterns of nine open‐habitat bird species in eight distantly located wildfires in the north‐eastern Iberian Peninsula. Methods We censused post‐fire bird composition by means of field transects and identified potential colonization sources from species–habitat suitability maps derived from atlas data. Results Our results showed strong significant differences in post‐fire species composition between burnt areas. Burnt areas located in areas with low probability of species presence before the fire event showed lower species occurrence and richness after the fire. Main conclusions These results do not support the idea that early successional stages and open habitats have a homogeneous community structure at regional scales and suggest that dispersal is a key constraint determining bird colonization of post‐fire habitats. Further attention should be paid to landscape heterogeneity as a key factor in determining population dynamics of open‐habitat species in the light of current and future land‐use changes in Mediterranean regions.     

Richness and structure of plant communities in temporary pools from western Morocco: influence of human activities

Temporary pools are numerous in coastal plains of Atlantic Morocco and have a rich and diverse flora. These habitats are increasingly under pressure by man impact through grazing by domestic livestock and the development of annual crops in their catchments. The objectives of this work were to evaluate the species richness and the species composition of the vegetation of a sample of 30 pools in this region, in order to assess the structure of the vegetation within pools and to evaluate the role of environmental and anthropogenic factors in their richness and species composition. The results highlighted the species richness of the pools with 300 species found among which annual species were heavily dominant. The structure of the vegetation varied within pools according to a topographical/flooding gradient and between pools in relation with the land use in the surrounding areas. Three vegetation belts were recognized from the centre to the periphery of the pool. The total species richness per pool was not found significantly related to environmental or anthropogenic factors. The species characteristics of the pools were found mostly in the centre and their number affected by hydrological factors and land use in the pool and in the surrounding areas. The species characteristics of woodland habitats and of agriculture crops were found mostly in the peripheral zone. Temporary pools maintain specific communities of both aquatic and amphibious species, probably because of the selection induced by water level variations. The peripheral zone, although often dominated by terrestrial species, is clearly interpreted as part of the pool. It contains amphibious species highly characteristic of the pool for which the irregular flooding is a key environmental factor which decreases competition.     

Contrasting responses of arable spiders to the landscape matrix at different spatial scales

Aim Animal communities can be influenced by the composition of the surrounding landscape through immigration. Depending on habitat preferences, however, the effect of the landscape matrix can be positive or negative and can vary with scale. We tested this idea with arable spiders and tried to infer dispersal distances from relationships between local density and landscape composition at different spatial scales. Location Thirty‐eight landscapes around the cities of Göttingen and Giessen, Germany. Methods Spiders were captured with pitfall traps in one field of winter wheat in each landscape. Landscape composition around the fields was characterized at 11 scales from 95 m to 3 km radius by land‐use mapping and subsequent GIS analysis. Correlation tests were performed between landscape composition and local densities or species richness. Results In both study regions, local species richness was enhanced by non‐crop habitats on a landscape scale. The overall densities of wolf spiders (Lycosidae), long‐jawed spiders (Tetragnathidae), crab spiders (Thomisidae), and dwarf sheet spiders (Hahniidae) increased significantly in landscapes with high percentages of non‐crop habitats. Out of the 40 species tested, 19 responded positively to the percentage of non‐crop habitats in the surrounding landscape, and five responded negatively. Depending on the species, the spatial scales with the highest explanatory power ranged from 95 m to 3 km radius around the study fields, potentially reflecting dispersal distances. Main conclusions Arable spider species showed contrasting responses to the landscape context with respect both to the direction and to the spatial scale of the relationship. The variation in landscape requirements among species ensures high spider densities in a wide range of situations, which contributes to ecosystem resilience. However, species richness of arable spiders depends on heterogeneous landscapes with high percentages of non‐crop habitats.     

中国阿勒泰地区鸟类物种编目、丰富度格局和区系组成

中国阿勒泰地区位于新疆北部, 与哈萨克斯坦、俄罗斯、蒙古国交界, 该区包含阿尔泰山及山前荒漠和绿洲, 属于全球200个生物多样性最丰富和最具代表性生态区之一的阿尔泰-萨彦岭生物热点地区。阿勒泰地区生境多样, 鸟类物种资源丰富。尽管以往曾在阿勒泰地区进行过一些鸟类调查, 但对于该地区不同景观和生境类型中鸟类物种丰富度和分布尚无详尽报道。本文通过2013-2016年在中国境内阿尔泰山及山前平原地区对不同生境类型中的鸟类进行实地调查, 并总结文献资料及观鸟爱好者的记录数据, 重新整理了阿勒泰地区鸟类名录及地理分布, 分析了鸟类的物种组成、区系成分; 通过鸟类分布位点数据, 选取气候、土地覆被类型、人类足迹指数及地形共4类环境因子作为自变量建立MaxEnt生态位模型, 通过模拟77种鸟类的适宜分布区并叠加分布图层, 获得了阿勒泰地区的鸟类物种丰富度分布格局。结果表明: 阿勒泰共记录鸟类344种, 隶属19目55科149属, 其中雀形目163种。在垂直海拔带上, 鸟类物种数分别为高山裸岩带24种, 高山草甸带35种, 山地森林草原带172种, 低山灌木带130种, 荒漠草原带84种, 平原绿洲带173种, 以及各海拔带的湿地与水域生境中水鸟92种; 在区系成分上, 以北方型鸟类为主(170种, 占49.4%), 其次为广布种(93种, 占27.0%)。阿尔泰山地的鸟类区系呈现出西伯利亚动物区系特征, 山前平原地区呈现蒙新区分布特征, 因此, 阿勒泰地区动物地理区系属于古北界欧洲-西伯利亚亚界阿尔泰-萨彦岭区阿尔泰亚区; 山前平原地区属于古北界中亚亚界蒙新区西部荒漠亚区。MaxEnt模型推测阿勒泰地区山前平原绿洲地区、山地森林草原带和低山灌木带具有较高的鸟类物种丰富度, 尤其是额尔齐斯河流域下游的绿洲带宽阔, 鸟类物种丰富, 而高山区和荒漠生境中鸟类物种相对较少。模型预测的结果与实际调查情况相符。阿勒泰地区应采用生态友好的经济发展策略, 加强对乔木和灌木的保护, 这有助于维持较高的鸟类物种多样性。此外, 降低生境破碎化不仅对该地区物种保护有重要作用, 也对维持阿尔泰-萨彦岭生物热点地区的山地鸟类多样性有重要意义。     

北京市平原区受胁鸟类栖息地识别和评价

在北京分布的受胁鸟类主要分布在平原区,而平原区为城市发展的主要区域,因此,在城市管理中融入受胁鸟类保护的内容十分必要。以北京市平原区分布的24种受胁鸟类为研究对象,以鸟类对栖息地的需求为分类依据,结合国家土地利用分类标准,采用人工目视解译法,在北京市平原区的高清卫星影像图上识别出5类一级鸟类栖息地和17类二级鸟类栖息地,得到北京市平原区鸟类栖息地分布图。使用24种受胁鸟类的空间分布模型掩膜鸟类栖息地分布,得到24种受胁鸟类的预测空间分布,叠加之后获得受胁鸟类丰富度分布格局,结果显示,水域是受胁鸟类丰富度最高的栖息地。将受胁鸟类丰富度分布格局与北京市国家级和市级自然保护区分布叠加进行空缺分析,结果显示：1）北京市的自然保护区多分布在山区,不能有效保护受胁鸟类;2）受胁鸟类的保护与平原区的城市建设、绿地管理关系密切。采用分区统计方法,计算各类栖息地中分布的平均鸟类种类数,作为栖息地保护行动优先级指标,得出湖泊、水库、坑塘、滩地、沼泽地等湿地区域是具有最高保护优先级的栖息地类型,在保护实践资源充足的情况下,应对各类栖息地开展综合保护。该研究首次为北京城市区域受胁鸟类保护提出空间参考和管理建议。     

Lost and found: Short-term dynamics of the flora on 100 small islands in the White Sea

The aim was to uncover factors that influence short-term (decade) flora dynamics and species richness of northern marine islets characterized by poor flora and weak anthropogenic pressure. The study used presence–absence data of vascular plant species on 100 small uprising islets of the Kandalaksha Gulf of White Sea (Northern Karelia, Russia). We investigated the influence of islands' attributes on species richness and rates of flora dynamics. Two island types were analyzed separately: younger, stone-like and older, islet-like (which generally are larger and have higher diversity of habitats). Sampled islands were studied via classical biogeographical per island approach and metapopulation per species approach. Stone-like islands had noticeably poorer flora with higher rates of immigration and extinction when compared to those of islet-like islands. The species number for islet-like islands correlated positively with number of habitats, abundance of different habitat types and island area. Species richness of stone-like islands correlated positively only with number of habitat types. Plant species associated with birds, crowberry thickets and coastal rocks were the most stable, and the species of disturbed habitats were significantly less stable. Floristic changes that have occurred have been caused by the massive establishment of new species rather than the extinction of pre-existing taxa. Thus, most of these islands are still in the colonization (assortative) stage. While we found no relationship between island area and species number for stone-like islands, this relationship was seen on islet-like islands.     

Determinants of species richness, endemism and turnover in European longhorn beetles

This study assessed the diversity patterns of a large family of beetles, Cerambycidae, in Europe and tested the following hypotheses: 1) richness gradients of this hyperdiverse taxon are driven by water and energy variables; 2) endemism is explained by the same factors, but variation between areas also reflects post‐glacial re‐colonization processes; and 3) faunal composition is determined by the same climatic variables and, therefore, beta diversity (species turnover) is related to richness gradients. Species richness, endemism and beta diversity were modelled using inventories of 37 European territories, built from a database containing the distributions of 609 species. Area, spatial position, and nine topographical and climatic variables were used as predictors in regression and constrained analysis of principal coordinates modelling. Species richness was mostly explained by a temperature gradient, which produced a south‐to‐north decreasing richness gradient. Endemism followed the same pattern, but was also determined by longitudinal variation, peaking in the southwestern and southeastern corners of the continent. Faunal turnover was explained by an important purely spatial pattern and a spatially structured environmental gradient. Thus, contrary to other groups, cerambycid richness was mostly explained by environmental energy, but not by water availability. Endemism was concentrated in the Iberian and Greek peninsulas, but not in Italy. Thus, the latter area may have been the major source of post‐glacial re‐colonization for European longhorn beetles or, otherwise, a poor refuge during glaciations. Turnover patterns were independent of the richness gradient, because northern faunas are nested in southern ones. Turnover, in contrast to richness, was driven by both the independent effects of climate and geographic constraints that might reflect dispersal limitation or stochastic colonization events, suggesting that richness gradients are more environmentally deterministic phenomena than turnover patterns.     

Vegetation heterogeneity and diversity in flat and mountain landscapes of Patagonia (Argentina)

Abstract. We studied floristic and diversity patterns and their environmental controls in two landscapes of contrasting topography in the Patagonian steppe. The analyses were focused on the effects of water availability gradients and landscape configuration on plant species distribution and coexistence. Floristic variation was investigated using Correspondence Analysis. The relationship between floristic and environmental variation was analyzed using Canonical Correspondence Analysis and correlation tests. We explored diversity patterns by relating spatial distance to floristic dissimilarities. The floristic gradient was determined by shrub and grass species and was related to precipitation in the flat area, and to precipitation, elevation and potential radiation in the mountain area. Site species richness increased with water availability in both areas. Mean site species richness and species turnover in space was higher in the mountain than in the flat area. Landscape species richness and floristic gradients were more concentrated in the mountain than in the flat area. In contrast to shrubs and grasses, forb species distributions were uncoordinated and probably independent of any environmental gradient. Our results suggest (1) that landscape configuration affects species composition and diversity through its direct effect on abiotic environmental heterogeneity, and (2) that the environmental controls of the community composition vary depending on the plant functional type considered.     

Disproportional risk for habitat loss of high‐altitude endemic species under climate change

The expected upward shift of trees due to climate warming is supposed to be a major threat to range‐restricted high‐altitude species by shrinking the area of their suitable habitats. Our projections show that areas of endemism of five taxonomic groups (vascular plants, snails, spiders, butterflies, and beetles) in the Austrian Alps will, on average, experience a 77% habitat loss even under the weakest climate change scenario (+1.8 °C by 2100). The amount of habitat loss is positively related with the pooled endemic species richness (species from all five taxonomic groups) and with the richness of endemic vascular plants, snails, and beetles. Owing to limited postglacial migration, hotspots of high‐altitude endemics are situated in rather low peripheral mountain chains of the Alps, which have not been glaciated during the Pleistocene. There, tree line expansion disproportionally reduces habitats of high‐altitude species. Such legacies of climate history, which may aggravate extinction risks under future climate change have to be expected for many temperate mountain ranges.     

Putting floodplain hyperdiversity in a regional context: an assessment of terrestrial–floodplain connectivity in a montane environment

Abstract Aim and location Alluvial flood plains support higher levels of vascular plant species richness than other terrestrial ecosystems. Whereas the spatial and temporal heterogeneity of these ecosystems has been considered the local determinant of high plant richness, regional influences, such as regional species pools have received little attention. In this study we surveyed plant species richness across the entire Nyack catchment (c. 21,000 ha), in Glacier National Park, USA, to determine the relation of upland ecosystem community structure to biodiversity patterns on montane floodplains that are relatively extensive and flood‐scoured ecosystems. Method We surveyed floodplain and other terrestrial ecosystems within the Nyack catchment using 50 × 2 m plots to record species present and visual estimates of percentage cover. Species pools from flood plains and three other terrestrial ecosystems (low elevation forests, sub‐Alpine forests and alpine) were analysed with nested subset analysis, detrended correspondence analysis (DCA), and an index of beta diversity to identify dissimilarity in species composition and richness, and the separate contributions of generalists (species occurring in more than one ecosystem) and specialists to richness in each ecosystem. Analysis of variance and post hoc Tukey–Kramer tests were used to identify where in the Nyack catchment each species was most abundant. Species life form and dispersal strategies were analysed to better understand influences on beta diversity. Results Our data show that in this pristine system, floodplain ecosystems host 202 (63%) of the 320 vascular plants identified within Nyack catchment. Of these species, the nested subset analysis showed that 146 (72%) are found in at least one adjacent upland ecosystem. While the DCA ordination scatter plots show statistically significant separations of ecosystems on the first two axes, values of beta diversity showed that substantial similarity exists between floodplain and all upland species pools. Further, of the 146 floodplain species shared with upland ecosystems, 61% were more frequent in upland ecosystems, whereas 55% were more abundant in uplands than flood plains (Tukey–Kramer P ≤ 0.05). Significant numbers of specialists were found on flood plains (24% of floodplain species), but also within upland ecosystems, where 23% and 40% of low elevation forest and alpine species were found to be specialists, respectively. Whereas 83% of herb generalists were wind dispersed, <70% of specialists were animal dispersed, indicating that similarity in species pools may be driven by wind dispersal. Main conclusions These results suggest a re‐evaluation of the contribution of floodplain ecosystems to regional plant species richness. While flood plains host specialists, other ecosystems had equal or higher levels of regional ‘endemism’. Furthermore, these data suggest that conservation of high levels of biodiversity on floodplain ecosystems may require consideration of upland ecosystems throughout the catchment as the majority of species were relatively rare on flood plains, indicating they may be sink habitats for some species.     

Butterfly community ecology: the influences of habitat type,weather patterns,and dominant species in a temperate ecosystem

We compared variation in butterfly communities across 3 years at six different habitats in a temperate ecosystem near Boulder, Colorado, USA. These habitats were classified by the local Open Space consortium as Grasslands, Tallgrass, Foothills Grasslands, Foothills Riparian, Plains Riparian, and Montane Woodland. Rainfall and temperature varied considerably during these years. We surveyed butterflies using the Pollard‐Yates method of invertebrate sampling and compared abundance, species richness, and diversity across habitats and years. Communities were most influenced by habitat, with all three quantitative measures varying significantly across habitats but only two measures showing variation across years. Among habitats, butterfly abundance was higher in Plains Riparian sites than in Montane Woodland or Grassland sites, though diversity was lowest in Plains Riparian areas. Butterfly species richness was higher in Foothills Riparian sites than it was in all but one other habitat (Tallgrass). Among years, butterfly abundance and species richness were lower during the year of least rainfall and highest temperatures, suggesting a substantial impact of the hot, dry conditions. Across habitats and years, butterfly abundance was consistently high at Plains Riparian and Foothills Riparian sites, and richness and diversity were consistently high in Foothills Riparian areas. These two habitats may be highly suitable for butterflies in this ecosystem, regardless of weather conditions. Generally low abundance and species richness in Montane Woodlands sites, particularly in 2002, suggested low suitability of the habitat to butterflies in this ecosystem, and this may be especially important during drought‐like conditions. Finally, to examine the effect that the presence of the very abundant non‐native species Pieris rapae L. (Lepidoptera: Pieridae) has on these communities, we re‐analyzed the data in the absence of this species. Excluding P. rapae dramatically reduced variation of both butterfly abundance and diversity across habitats, highlighting the importance of considering community membership in analyses like ours.     

The vegetation of the Farasān Islands,Red Sea,Saudi Arabia

Abstract. Classification of the vegetation of the Farasān Islands using TWINSPAN technique resulted in the recognition of seven community types associated with seven different habitat types: silty runnels, palm orchards, rocky plains, rocky plateau crevices, coastal sand dunes, sand plains, and mangroves. These communities were dominated or co-dominated by 13 perennial species; 87 associate species were recorded in the study area with chamaephytes dominating the life-form spectrum. Canonical Correspondence Analysis (CCA) indicated that organic carbon, soil moisture, silt, electrical conductivity and calcium carbonate were the major edaphic gradients controlling the distribution of the plant communities on the Farasān Islands. Higher species richness was recorded in the plant communities inhabiting the palm orchards, the crevices of the rocky plateau, silty runnels, rocky plains and rocky plateau, while those of the mangrove and sand formations (dunes and plains) showed a lower species richness. Soil texture and organic matter are the main factors promoting species diversity in the more diversified habitats, while high salinity and calcium carbonate are the main factors associated with lower species diversity in the less diversified habitats of the study area.     

黄鼬(Mustela sibirica)体型大小的性二型及地理变异

本文报道黄鼬体型大小的性二型及其与地理变异的关系。个体大小的性二型现象很可能与繁殖行为有关,许多在繁殖季节有争偶行为的一雄多雌兽类,雄性都有较大的个体。     

Pervasive migration across rainforest and sandy coastal plain Aechmea nudicaulis (Bromeliaceae) populations despite contrasting environmental conditions

Understanding the colonization of extreme marginal habitats and the relative roles of space and environment in maintaining peripheral populations remains challenging. Here, we leverage a system of pairs of rainforest and sandy coastal plain communities that allow us to decouple spatial and environmental effects in the population structure and migration rates of the bromeliad Aechmea nudicaulis. Structure and gene flow between populations were estimated from Bayesian clustering and coalescent‐based migration models applied to chloroplast sequence and nuclear microsatellite data. Contrary to our initial expectation, the sharp environmental gradient between rainforest and sandy plains does not seem to have affected the colonization and migration dynamics in A. nudicaulis. Our analyses uncover pervasive gene flow between neighbouring habitats in both chloroplast and nuclear data despite the striking differences in environmental conditions. This result is consistent with a scenario of repeated colonization of the sandy coastal plains from forest populations through seed dispersal, as well as the maintenance of gene flow between habitats through pollination. We also recovered a broad north/south population structure that has been found in other Atlantic rainforest groups and possibly reflects older phylogeographic dynamics.