国家重点保护野生植物的保护现状及潜在分布区预测分析

野生植物是自然生态系统的重要组成部分,中国是野生植物种类最丰富的国家之一。研究国家重点保护野生植物的分布特征、保护现状以及潜在分布区,对于制定与支持生物多样性保护策略具有重要意义。该研究基于1 032种(隶属于129科315属)国家重点保护野生植物,利用前5%丰富度算法识别其热点地区,并与自然保护区叠加评估其保护成效、确定保护空缺,进而运用MaxEnt模型预测了国家重点保护野生植物的潜在分布区分布与变化趋势。结果表明:(1)中国南部和西南部是国家重点保护野生植物物种丰富度最高的地区,尤其是四川中部、云南南部和东南部、广西北部、广东北部与海南。(2)热点网格的保护成效分析表明,171个(85.50%)热点网格得到了有效保护(含80.50%的物种),29个(14.50%)热点网格未得到自然保护区的保护(含51.20%物种)。(3)通过比较当前与未来气候变化下国家重点保护野生植物的潜在分布区分布,发现未来潜在分布区将向西藏东南部、广西西南部、广东南部以及福建南部等地扩张,而向环四川盆地、云南南部和贵州南部等地缩减。因此,需要加强这些区域生物多样性的动态监测,持续关注气候变化对该区域国家重点保护野生植物的影响。基于该研究所确定的热点网格、保护成效以及潜在分布区的分析结果,可为国家重点保护野生植物多样性优先保护区的确定和保护政策的制定提供有力的数据支持与参考。     

Crinum alkaloids: their chemistry and biology

The current staus of research of free and glycosylated alkaloids occuring in members of the genus Crinum is reviewed. The distribution, isolation, spectral properties, structural properties, inter conventions and biological acitivities of these alkaloids are presented.     

Effect of water clarity on the distribution of marine birds in nearshore waters of Monterey Bay, California

ABSTRACT.   The distribution of marine birds relative to water clarity was examined in the nearshore waters of Monterey Bay, California. I conducted nine at-sea surveys in 1999 and 2000 and simultaneously recorded water clarity and the density of five taxa of marine birds. Among plunge-divers, Forster's Terns ( Sterna forsteri ) occurred more frequently than expected over turbid water (<2.5 m Secchi depth) and, among pursuit-diving species, Brandt's Cormorants ( Phalacrocorax penicillatus ) occurred most often in the clearest water available (>5 m Secchi depth). Turbidity in Monterey Bay may be caused by suspended organic matter, including phytoplankton, during summer and fall. Forster's Tern may prefer such areas because small fish are likely to occur near this potential food source. Brandt's Cormorants probably rely on vision to catch fish near the bottom and turbid water may reduce available light and limit visual acuity. The distribution of Brown Pelicans (Pelecanus occidentalis ), Western/Clark's Grebes (Aechmophorus occidentalis/clarkii ), and Marbled Murrelets ( Brachyramphus marmoratus ) did not appear to be influenced by turbidity levels, indicating that some seabirds use marine habitats with a wide range of water clarities.     

Distribution, abundance, and conservation of Vinaceous Amazons (Amazona vinacea) in Argentina and Paraguay

ABSTRACT.   Vinaceous Amazons ( Amazona vinacea ) are endemic to the Atlantic forest of southeastern Brazil, eastern Paraguay, and the province of Misiones in Argentina. We searched for Vinaceous Amazons throughout the western part of its range in Argentina and Paraguay during 1639 days of fieldwork from 1997 to 2006. These parrots have disappeared from most areas where they were historically recorded in these countries, and are now limited to a few sites in northeastern Paraguay and central Misiones (Argentina). We estimate the minimum remaining populations at 220 individuals in Paraguay and 203 individuals in Argentina. Important sites for the species are (1) the farming area from San Pedro to Tobuna (Misiones, Argentina) and (2) the Itaipú reserves complex and Reserva Natural Privada Itabó (Paraguay). In our surveys, Vinaceous Amazons were absent from the largest tracts of forest in Misiones, and were most often observed feeding, roosting, and nesting in small forest remnants and in agricultural areas that included forest fragments and isolated trees. Threats to amazons in these areas include nest poaching, forest clearing, and being shot as a crop pest. We confirmed 40 Vinaceous Amazons kept as pets in 35 homes between San Pedro and Tobuna. Environmental education and law enforcement are urgently needed to reduce threats in populated areas, and subsistence farmers need technical and logistical support to slow or stop the conversion of forest into cropland. Finally, additional study is needed to determine this amazon's habitat preferences, nest site requirements, and demography in different habitats.     

The changing otter population of Britain 1700–1989

Otters Lutra lutra were persecuted increasingly in Britain for fishery protection and for sport throughout the 18th and 19th centuries. There are indications of a population recovery occurring during the 1914–1918 war with the temporary cessation of hunting and keepering. Intensive otter hunting with packs of hounds throughout the 1920s and 1930s appears to have stressed the population by altering the age structure. A catastrophic decline occurring simultaneously over England, Wales and southern Scotland, but most severe in the south-east and starting in 1957–1958, appears to have been triggered in this stressed population by a single new factor, pollution of the rivers by organochlorine insecticides. The trough in the decline may have occurred around 1977— 1979. The first signs of rivers being re-occupied by otters have been seen by the early 1980s and partial recovery seems possible with legal protection and improved water quality.     

Climate change at the landscape scale: predicting fine-grained spatial heterogeneity in warming and potential refugia for vegetation

Current predictions of how species will respond to climate change are based on coarse‐grained climate surfaces or idealized scenarios of uniform warming. These predictions may erroneously estimate the risk of extinction because they neglect to consider spatially heterogenous warming at the landscape scale or identify refugia where species can persist despite unfavourable regional climate. To address this issue, we investigated the heterogeneity in warming that has occurred in a 10 km × 10 km area from 1972 to 2007. We developed estimates by combining long‐term daily observations from a limited number of weather stations with a more spatially comprehensive dataset (40 sites) obtained during 2005–2006. We found that the spatial distribution of warming was greater inland, at lower elevations, away from streams, and at sites exposed to the northwest (NW). These differences corresponded with changes in weather patterns, such as an increasing frequency of hot, dry NW winds. As plant species were biased in the topographic and geographic locations they occupied, these differences meant that some species experienced more warming than others, and are at greater risk from climate change. This species bias could not be detected at coarser scales. The uneven seasonal nature of warming (e.g. more warming in winter, minimums increased more than maximums) means that climate change predictions will vary according to which predictors are selected in species distribution models. Models based on a limited set of predictors will produce erroneous predictions when the correct limiting factor is not selected, and this is difficult to avoid when temperature predictors are correlated because they are produced using elevation‐sensitive interpolations. The results reinforce the importance of downscaling coarse‐grained (∼50 km) temperature surfaces, and suggest that the accuracy of this process could be improved by considering regional weather patterns (wind speed, direction, humidity) and topographic exposure to key wind directions.     

Individual‐based and stochastic modeling of cell population dynamics considering substrate dependency

In this article, we propose an individual‐based and stochastic modeling approach that is capable of describing the bacterial cell population dynamics during a batch culture. All stochastic nature inherent in intracellular molecular level reactions and cell division processes were considered in a single model framework by embedding a sub‐model describing individual cell's growth kinetics in a discrete event simulation algorithm. The resultant unique feature of the model is that the effects of the stochasticities on the cell population dynamics can be investigated for different substrate‐dependent cell growth kinetics. When Monod kinetics was used as the sub‐model, the stochasticities only slightly affected the cell mass increase and substrate consumption profiles during the batch culture although they were still important in describing the changes of cell population distributions. When Andrews substrate inhibition kinetics was used, however, it was revealed that the overall cell population dynamics could be seriously influenced by the stochasticities. Under a critical initial substrate level, the cell population could proliferate against the substrate inhibition only when the stochasticities were considered. Biotechnol. Bioeng. 2009;103: 891–899. © 2009 Wiley Periodicals, Inc.     

A phylogeographical analysis across three biogeographical provinces of the south-eastern Pacific: the case of the marine gastropod Concholepas concholepas

Aim The present‐day population structure of a species reflects the influence of population history as well as contemporary processes. Little is known about the mechanisms that have shaped the geographical distribution of genetic diversity in marine species present on the south‐eastern Pacific (SEP) coast. Here we provide the first comprehensive phylogeographical study of a species distributed along the SEP coast by analysing the endemic and emblematic muricid gastropod Concholepas concholepas. Location The study localities were distributed along the SEP coast ranging from Matarani (11° S) to Puerto Eden (49° S), crossing three major biogeographical provinces: Peruvian Province, Intermediate Area and Magellanic Province. Methods A total of 337 specimens of C. concholepas were collected from 14 localities in the three biogeographical provinces/areas. Mitochondrial cytochrome oxidase I (COI) gene partial sequences (658 bp) were obtained and analysed using coalescence‐based methods to infer molecular diversity and phylogeographical patterns. Results Across the 337 individuals, we found a large diversity, with a total of 179 haplotypes at the COI gene fragment. Although a slight decrease in gene diversity was observed from north to south, an analysis of molecular variance did not reveal any significant spatial population differentiation from Peru to the tip of Chile, not even across the recognized biogeographical boundaries at 30° S and 42° S. In addition, a star‐like haplotype network suggested the past occurrence of a rapid demographic and geographical expansion over the total range examined. Calculations of the onset of this expansion suggest that it might be due to climatic conditions during the period of the marine isotope stage 11 (MIS 11, 400,000 years ago), the longer and warmer interglacial episode during the Pleistocene epoch. Main conclusions Our phylogeographical analyses indicate that in the recent past C. concholepas mitochondrial DNA lineages underwent a sudden population expansion event. In addition, our data do not support the hypothesis of concordance between biogeographical barriers and phylogeographical breaks along the SEP coast. These two results are in accordance with the paradigm of high larval dispersal ability in marine species with an extended pelagic larval phase.     

A Bayesian Long‐term Survival Model Parametrized in the Cured Fraction

The main goal of this paper is to investigate a cure rate model that comprehends some well‐known proposals found in the literature. In our work the number of competing causes of the event of interest follows the negative binomial distribution. The model is conveniently reparametrized through the cured fraction, which is then linked to covariates by means of the logistic link. We explore the use of Markov chain Monte Carlo methods to develop a Bayesian analysis in the proposed model. The procedure is illustrated with a numerical example.