秋浦河源国家湿地公园溪流鱼类群落的时空格局

确定溪流鱼类群落的时空格局及其形成机制是开展鱼类物种多样性保护和管理的科学基础。该文于2012年5月和10月两次对秋浦河源国家湿地公园境内的24个可涉水河段取样,共采集鱼类29种,隶属10科4目。研究了溪流鱼类群落结构及其多样性的时空格局,并解析了局域栖息地条件与支流空间位置变量对鱼类群落的影响。鱼类多样性的时空变化显著,鱼类多样性总体上为二级溪流高于一级溪流,10月份高于5月份。流量量级、底质粗糙度及异质性、水温和水深等对鱼类多样性及群落结构的空间变化影响显著。鱼类群落结构符合嵌套格局,季节动态不显著,上游鱼类群落呈现为下游群落的嵌套子集。一、二级溪流间的群落结构尽管存在部分重叠但差异显著,且这种差异主要源于稀有花鳅(Cobitis rarus)、吻虾虎鱼(Ctenogobius spp.)、宽鳍鱲(Zacco platypus)、尖头鱥(Phoxinus oxycephalus)、高体鰟鲏(Rhodeus ocellatus)和原缨口鳅(Vanmanenia stenosoma)等鱼类相对多度的空间变化,其中,除尖头鱥的多度在一级溪流中更高外,其他5种鱼类均在在二级溪流更高。     

珠江流域植被覆盖时空变化分析

为阐明珠江流域植被覆盖变化的整体状况,基于RS与GIS技术,应用美国国家航天航空局最新的全球植被指数变化研究数据(GIMMS),对珠江流域1982~2003年间的地表植被覆盖的空间分布及时间序列变化进行了综合分析。结果表明:(1)22年来,珠江流域大部分地区的NDVI都呈现不同程度的下降趋势,表明珠江流域植被活动在减弱;(2)从季节变化来看,珠江流域平均植被覆盖除春季呈不显著上升外,其余各季均呈不显著下降趋势;(3)空间上,中下游地区都呈现不同程度的下降趋势,其中珠江三角洲地区达到了极显著水平;而上游南、北盘江流域、右江、左江及郁江流域则呈不显著增加趋势。这种空间异质性是由于城市化过程、农业生产活动、区域气候特征等综合因素作用的结果。     

Patterns and processes in plant phylogeography in the Mediterranean Basin. A review

Phylogeography, born to bridge population genetics and phylogenetics in an explicit geographic context, has provided a successful platform for unveiling species evolutionary histories. The Mediterranean Basin, one of the earth's 25 biodiversity hotspots, is known for its complex geological and palaeoclimatic history. Aiming to throw light on the causes and circumstances that underlie such a rich biota, a review of the phylogeographic literature on plant lineages from the Mediterranean Basin is presented focusing on two levels. First, phylogeographic patterns are examined, arranged by potential driving forces such as longitude, latitude – and its interaction with altitude –, straits or glacial refugia. Spatial coincidences in phylogeographic splits are found but, in comparison to other regions such as the Alps or North America, no largely common phylogeographic patterns across species are found in this region. Factors contributing to phylogeographic complexity and scarcity of common patterns include less drastic effects of Pleistocene glaciations than other temperate regions, environmental heterogeneity, the blurring of genetic footprints via admixing over time and, for older lineages, possibly a greater stochasticity due to the accumulation of responses to palaeoclimatic changes. At a second level, processes inferred in phylogeographically framed studies that are potential drivers of evolution are examined. These include gradual range expansion, vicariance, long-distance dispersal, radiations, hybridization and introgression, changes in reproductive system, and determinants of successful colonization. Future phylogeographic studies have a great potential to help explaining biodiversity patterns of plant groups and understanding why the Basin has come to be one of the biodiversity hotspots on earth. This potential is based on the crucial questions that can be addressed when geographic gaps are adequately filled (mainly northern Africa and the eastern part of the region), on the important contribution of younger lineages – for which phylogeographic approaches are most useful – to the whole diversity of the Basin, and on the integration of new methods, particularly those that allow refining the search for spatio-temporal concordance across genealogies.     

Ground-truthing the impact of invasive species: spatio-temporal overlap between native least chub and introduced western mosquitofish

Western mosquitofish (Gambusia affinis) are one of the most destructive introduced species in the American West. The negative impact of introduced species on native taxa depends on their spatio-temporal overlap, which will determine the availability of refugia for native species. Experiments on the mechanisms underlying the interactions between introduced and native species rarely address habitat use, overlap, and refugia because individuals are confined to enclosures. In a previous study we used cages, microcosms, and aquaria to show that mosquitofish could prey on and out-compete native least chub (Iotichthys phlegethontis). In this study, we examined the spatio-temporal overlap between mosquitofish and least chub under natural conditions. We found periods of overlap and partitioning in the seasonal and diel habitat use of these species. Both species used shallow habitats during the day and night throughout the spring when least chub were spawning. Predation by adult mosquitofish on young least chub during the spring likely explains the reduction in least chub recruitment in the presence of mosquitofish. During the summer least chub avoided mosquitofish by exclusively using cooler habitats, or by occupying deeper, cooler habitats during the day when mosquitofish were active, and shallower, warmer habitats at night when mosquitofish were inactive. A shift to cooler habitats in the presence of mosquitofish may result in decreased growth and fecundity of least chub. However, we suggest that a reduction of warm shallow habitat may have a disproportionately greater negative impact on mosquitofish than species native to temperate regions, such as least chub. Habitat manipulations that reduce or eliminate warm habitats may ameliorate the harmful effects of mosquitofish and promote the long-term persistence of native taxa.     

Medical records vs. interview responses: a comparative analysis of selected variables for linked birth defect cases

BACKGROUND: Data pertaining to birth defects are subject to certain limitations depending on the collection method. This study compares the agreement of data from medical records and maternal interviews. METHODS: The medical records and maternal interviews were linked for 1017 deliveries. Prevalence, concordance and kappa coefficients were calculated for maternal gestational and non-gestational diabetes, insulin use, seizures/epilepsy, Hispanic ethnicity, and infant/fetus sex. RESULTS: The prevalence of non-gestational diabetes was 4.3% in the medical records and 3.4% in the maternal interviews, with 98.1% agreement. The prevalence of gestational diabetes was 7.9% in medical records and 9.2% in maternal interviews, with 94.3% agreement. Similar prevalences and high levels of agreement were observed between the two systems for infant/fetus sex and mother's Hispanic ethnicity. Although high concordance was observed for seizures/epilepsy, kappa value was moderate. CONCLUSIONS: The availability of two distinct sources of data provides an exceptional opportunity to compare and validate both data sources. We found that the data for certain variables from maternal interviews strongly agreed with information from medical records. However, the extent of that agreement depended on the type of variable measured. Our results suggest that for some variables such as demographic variables, researchers can use either of the two data sources.     

Extreme land-cover and biodiversity change as an outcome of land abandonment on a Mediterranean island (eastern Adriatic)

Understanding land abandonment and the resulting changes in land cover provides data for suitable reaction to habitat and species losses this process brings. This study aimed to define land-cover types and their biodiversity, record spatio-temporal changes and detect the trajectories and magnitude of these changes. The study was conducted on the island of Molat in the eastern Adriatic Sea. Land cover was defined for different years (1910, 1959, 1986, 2006) using remote sensing and recent vegetation sampling. The obtained land-cover maps were used for spatio-temporal analysis of land-cover change. Open vegetation units of rocky grassland, mesophilous grasslands and farm land dominated in 1910, covering 90% of the island. The observed changes occurred in trajectories through semi-open towards closed vegetation. In 2006, closed vegetation dominated, covering approximately 70% of the island area. The overall land-cover change was extreme, occurring over 90% of the island surface. Biodiversity analysis was related to the present land-cover types and change trajectories, and showed a considerable decline of species richness towards closed vegetation types. All observed changes were correlated to island depopulation and land abandonment. Re-population and encouragement of agro-pastoral activities should reduce habitat and species loss in the process of secondary succession.