Testing hypotheses driving genetic structure in the cooperatively breeding Brown‐headed Nuthatch Sitta pusilla

Habitat fragmentation has often been implicated in the decline of many species. For habitat specialists and/or sedentary species, loss of habitat can result in population isolation and lead to negative genetic effects. However, factors other than fragmentation can often be important and also need to be considered when assessing the genetic structure of a species. We genotyped individuals from 13 populations of the cooperatively breeding Brown‐headed Nuthatch Sitta pusilla in Florida to test three alternative hypotheses regarding the effects that habitat fragmentation might have on genetic structure. A map of potential habitat developed from recent satellite imagery suggested that Brown‐headed Nuthatch populations in southern Florida occupied smaller and more isolated habitat patches (i.e. were more fragmented) than populations in northern Florida. We also genotyped individuals from a small, isolated Brown‐headed Nuthatch population on Grand Bahama Island. We found that populations associated with more fragmented habitat in southern Florida had lower allelic richness than populations in northern Florida (P = 0.02), although there were no differences in heterozygosity. Although pairwise estimates of F_ST were low overall, values among southern populations were generally higher than northern populations. Population assignment tests identified K = 3 clusters corresponding to a northern cluster, a southern cluster and a unique population in southeast Florida; using sampling localities as prior information revealed K = 7 clusters, with greater structure only among southern Florida populations. The Bahamas population showed moderate to high differentiation compared with Florida populations. Overall, our results suggest that fragmentation could affect gene flow in Brown‐headed Nuthatch populations and is likely to become more pronounced over time.     

风景园林与绿色基础设施在城市流域水资源规划中的重要作用

通过绿色基础设施途径,处理美国波士顿北部的马萨诸塞州城市流域的水资源规划问题。从多个尺度为风景园林师提供水资源规划的经验与启发,探究公众对新型绿色基础设施解决方案的态度与偏好,以及公众偏好对于整体规划设计的重要作用。     

神农架北坡堵河源自然保护区植物多样性研究

为建立自然保护区,保护神农架北坡堵河源地区丰富的生物多样性资源,并为神农架地区植物起源、植被演替以及生物多样性和濒危物种状况深入、准确评价提供基础数据,2002年,采用路线调查与标准地调查相结合的方法,结合历史资料,对堵河源地区的野生植物资源进行了实地野外调查研究,分析了植物区系和植物多样性及其受威胁状况。结果表明:(1)该保护区具有丰富的植物物种多样性,有维管束植物174科730属1733种(含亚种、变种),其中,国家重点保护野生植物有23种;(2)该区植物区系成分具有复杂性、多样性,拥有中国种子植物分布区类型属级水平的全部类型,但明显偏重于温带性质。且植物区系起源古老,有中国特有分布属37个,其中,古特有属27个;(3)该区具有丰富的植被类型,包括4个植被型组,8个植被型,26个群系,具有较高的保护和科研价值。同时针对保护区植物多样性受威胁状况,提出了植被恢复、加强防火设备设施建设、生态移民、保护珍稀濒危植物及社区共管是保护植物多样性的有效措施。     

中国苦苣苔科植物的多样性与地理分布（附表）

物种多样性编目是开展生物多样性保护的重要基础,该研究结合最新分子系统学研究成果以及近年来发表的新资料,对中国苦苣苔科植物多样性和地理分布数据进行了统计和分析.结果表明:中国苦苣苔科植物共有44属671种(含种下单位,下同),其中特有属11个;特有种573种,占总种数的85.39%.种数最多的10个属依次为广义报春苣苔属(180种)、广义马铃苣苔属(122种)、石蝴蝶属(39种)、半蒴苣苔属(39种)、芒毛苣苔属(38种)、长蒴苣苔属(35种)、石山苣苔属(31种)、吊石苣苔属(31种)、蛛毛苣苔属(28种)、汉克苣苔属(22种).在地理分布上,种数排名前10的省份(区)有广西(260种,33属)、云南(236种,30属)、贵州(96种,28属)、广东(93种,17属)、四川(85种,21属)、湖南(58种,13属)、西藏(39种,9属)、湖北(29种,15属)、福建(26种,13属)、江西(25种,9属).含中国特有苦苣苔科植物的属中排前10位的分别为广义报春苣苔属(178种)、广义马铃苣苔属(119种)、石蝴蝶属(37种)、半蒴苣苔属(35种)、石山苣苔属(30种)、长蒴苣苔属(29种)、吊石苣苔属(23种)、蛛毛苣苔属(19种)、芒毛苣苔属(19种)、汉克苣苔属(11种).这表明中国南部和西南部是苦苣苔科植物的一个分布中心,特别是石灰岩地区有着高度的物种多样性和特有性,广义报春苣苔属、广义马铃苣苔属、石蝴蝶属、半蒴苣苔属、石山苣苔属、吊石苣苔属等为我国典型的优势属.此外,根据目前的研究现状,还对我国苦苣苔科植物资源的调查、分类学和系统发育研究、保护和可持续利用等进行了讨论.     

水土保持与生态农业旅游技术研究--以四川省南充市嘉陵区木老乡生态农业旅游区为例

嘉陵江流域水土流失日趋严重,已成为农业生态环境最突出的问题。从治理水土流失的角度出发,提出了以营造经果林和水保林为主,配合蔬菜、花卉、生草及植被恢复,结合观光旅游和农民培训的“生态农业旅游”技术与示范。取得了良好的社会效益与经济效益。通过对试验区和试验辐射区的研究,提出了在发展生态农业旅游时必须坚持的原则和注意的问题。     

New evidence for hybrid zones of forest and savanna elephants in Central and West Africa

The African elephant consists of forest and savanna subspecies. Both subspecies are highly endangered due to severe poaching and habitat loss, and knowledge of their population structure is vital to their conservation. Previous studies have demonstrated marked genetic and morphological differences between forest and savanna elephants, and despite extensive sampling, genetic evidence of hybridization between them has been restricted largely to a few hybrids in the Garamba region of northeastern Democratic Republic of Congo (DRC). Here, we present new genetic data on hybridization from previously unsampled areas of Africa. Novel statistical methods applied to these data identify 46 hybrid samples – many more than have been previously identified – only two of which are from the Garamba region. The remaining 44 are from three other geographically distinct locations: a major hybrid zone along the border of the DRC and Uganda, a second potential hybrid zone in Central African Republic and a smaller fraction of hybrids in the Pendjari–Arli complex of West Africa. Most of the hybrids show evidence of interbreeding over more than one generation, demonstrating that hybrids are fertile. Mitochondrial and Y chromosome data demonstrate that the hybridization is bidirectional, involving males and females from both subspecies. We hypothesize that the hybrid zones may have been facilitated by poaching and habitat modification. The localized geography and rarity of hybrid zones, their possible facilitation from human pressures, and the high divergence and genetic distinctness of forest and savanna elephants throughout their ranges, are consistent with calls for separate species classification.     

Environmental Drivers and Spatial Prediction of the Critically Endangered Species <i>Thuja sutchuenensis</i> in Sichuan-Chongqing,China

Identifying the ecological environment suitable for the growth of Thuja sutchuenensis and predicting other potential distribution areas are essential to protect this endangered species. After selecting 24 environmental factors that could affect the distribution of T. sutchuenensis, including climate, topography, soil and Normalized Difference Vegetation Index (NDVI), we adopted the Random Forest-MaxEnt integrated model to analyze our data. Based on the Random Forest study, the contribution of the mean temperature of the warmest quarter, mean temperature of the coldest quarter, annual mean temperature and mean temperature of the driest quarter was large. Based on MaxEnt model prediction outputs, the potential distribution map not only identified areas that originally recorded T. sutchuenensis, such as Xuanhan County, Kai County and Chengkou County, but also identified highly suitable distribution areas where T. sutchuenensis may exist, including Wanyuan County, Sichuan Province, and the junction of Chongqing and Hubei Province. This provides a more explicit geographic range for ex situ conservation and reintroduction of T. sutchuenensis. Our results also indicate that, in addition to climate factors, topography and soil factors are also important environmental factors that affect distribution. This provides a theoretical basis for subsequent laboratory construction to simulate the indoor growth of T. sutchuenensis.