Effects of Social Structure and Prey Dynamics on Extinction Risk in Gray Wolves

Extinction models based on diffusion theory generally fail to incorporate two important aspects of population biology—social structure and prey dynamics. We include these aspects in an individual-based extinction model for small, isolated populations of the gray wolf (Canis lupus). Our model predicts mean times to extinction significantly longer than those predicted by more general (diffusion) models. According to our model, an isolated population of 50 wolves has a 95% chance of surviving just 9 years and only a 30% chance of surviving beyond 100 years. Reflecting the influence of social structure, a wolf population initially comprising 50 individuals is expected to persist only a few years longer, on average (71 years), than is a population initially comprising just a single reproductive pair (62 years). In contrast, substantially greater average prey abundance leads to dramatically longer expected persistence times. Autocorrelated prey dynamics result in a more complex distribution of extinction times than predicted by many extinction models. We contend that demographic stochasticity may pose the greatest threat to small, isolated wolf populations, although environmental stochasticity and genetic effects may compound this threat. Our work highlights the importance of considering social structure and resource dynamics in the development of population viability analyses.     

Mitochondrial DNA Variability in Italian and East European Wolves: Detecting the Consequences of Small Population Size and Hybridization

Abstract: The Italian wolf ( Canis lupus ) population has declined continuously over the last few centuries and become isolated as a result of the extermination of other populations in central Europe and the Alps during the nineteenth century. In the 1970s, approximately 100 wolves survived in 10 isolated areas in the central and southern Italian Apennines. Loss of genetic variability, as suggested by preliminary studies of mitochondrial DNA (mtDNA) sequences, hybridization with feral dogs, and the illegal release of captive, non-native wolves are considered potential threats to the viability of the Italian wolf population. We sequenced 546 base pairs of the mtDNA control region in a comprehensive set of Italian wolves and compared them to those of dogs and other wolf populations from Europe and the Near East. Our data confirm the absence of mtDNA variability in Italian wolves: all 101 individuals sampled across their distribution in Italy had the same, unique haplotype, whereas seven haplotypes were found in only 26 wolves from an outbred population in Bulgaria. Most haplotypes were specific either to wolves or dogs, but some east European wolves shared haplotypes with dogs, indicative of hybridization. In contrast, neither hybridization with dogs nor introgression of non-native wolves was detected in the Italian population. These findings exclude the introgression of dog genes via matings between male wolves and female dogs, the most likely direction of hybridization. The observed mtDNA monomorphism is the possible outcome of random drift in the declining and isolated Italian wolf population, which probably existed at low effective population size during the last 100–150 years. Low effective population size and the continued loss of genetic variability might be a major threat to the long-term viability of Italian wolves. A controlled demographic increase, leading to recolonization of the historical wolf range in Italy, should be enforced.     

Hunting Effects on Favourable Conservation Status of Highly Inbred Swedish Wolves

The wolf (Canis lupus) is classified as endangered in Sweden by the Swedish Species Information Centre, which is the official authority for threat classification. The present population, which was founded in the early 1980s, descends from 5 individuals. It is isolated and highly inbred, and on average individuals are more related than siblings. Hunts have been used by Swedish authorities during 2010 and 2011 to reduce the population size to its upper tolerable level of 210 wolves. European Union (EU) biodiversity legislation requires all member states to promote a concept called “favourable conservation status” (FCS) for a series of species including the wolf. Swedish national policy stipulates maintenance of viable populations with sufficient levels of genetic variation of all naturally occurring species. Hunting to reduce wolf numbers in Sweden is currently not in line with national and EU policy agreements and will make genetically based FCS criteria less achievable for this species. We suggest that to reach FCS for the wolf in Sweden the following criteria need to be met: (1) a well‐connected, large, subdivided wolf population over Scandinavia, Finland, and the Russian Karelia‐Kola region should be reestablished, (2) genetically effective size (N_e) of this population is in the minimum range of N_e = 500–1000, (3) Sweden harbors a part of this total population that substantially contributes to the total N_e and that is large enough to not be classified as threatened genetically or according to IUCN criteria, and (4) average inbreeding levels in the Swedish population are <0.1. Efectos de la Cacería sobre el Estatus de Conservación Favorable de Lobos Suecos con Endogamia Alta     

Conservation Value of Sites of Hybridization in Peripheral Populations of Rare Plant Species

Abstract:  Populations at the periphery of a species' range are of interest to conservation biologists because they can show marked genetic differentiation from populations at the center of a range and because of potential hybridization among rare and common species. We examined two closely related Cyclamen species. One is a narrow endemic, and the other is more geographically widespread (both protected by law in continental southern France). We used floral traits and genetic variability to test for hybridization among the species in peripheral populations of the rare species. The species co-occurred on Corsica in a disjunct, peripheral part of the distribution of the endemic species and in an ecologically marginal area for the widespread species. The two species have hybridized and the endemic species showed high levels of introgression with its widespread congener. Genetic and floral variability in sites with both species was markedly higher than in sites with a single species. Our results highlight the need for a conservation strategy that integrates hybrid populations because they represent a source of novel diversity that may have adaptive potential.     

Persistence of oxyfluorfen in soil and detection of its residues in rice crop

Oxyfluorfen is a post-emergence herbicide used for control of annual and perennial broad-leaf weeds and sedges in rice. There is increasing concern about persistence of pesticide residues in soils, agricultural products and sub-sequent contamination of ground water through runoff, leaching and drift. Thus, persistence of oxyfluorfen was evaluated under field conditions in a rice cropping system. Oxyfluorfen was sprayed at 240 and 500 g ai ha^?1 application rates to the rice crop as post-emergence herbicide. Paddy grains, straw and soil samples were collected at harvest and analyzed for oxyfluorfen residues by HPLC. Straw samples contained 0.01 and 0.03 µg g^?1 oxyfluorfen residues at 240 and 500 g ha^?1 concentrations, respectively. In the soil, 0.028 and 0.03 µg g^?1 of oxyfluorfen residues were detected when applied at 240 and 500 g ai ha^?1, respectively. However, in rice grains, 0.018 and 0.106 µg g^?1 of oxyfluorfen residues were found in 240 and 500 g ai ha^?1 treated plots. In light of the potential adverse effects of oxyfluorfen, it is important to determine herbicide levels in these crops.     

Spontaneous Interspecific Hybridization and Patterns of Pollen Dispersal in Ex Situ Populations of a Tree Species (Sinojackia xylocarpa) that is Extinct in the Wild

Abstract:  For endangered plants interspecific hybridization occurring in ex situ collections may lead to failure of reintroduction actions. We used Sinojackia xylocarpa , a well documented Chinese endemic species that is extinct in the wild, as a model case to address this concern. We used paternity analyses to assess the spontaneous hybridization and patterns of pollen flow between S. xylocarpa and its congener species, S. rehderiana , in conserved populations in Wuhan Botanic Garden. Interspecific hybridization events were detected in seven out of eight maternal trees of S. xylocarpa , and an average of 32.7% seeds collected from maternal trees of S. xylocarpa were hybrids. The paternity of 93 out of 249 seedlings from S. xylocarpa assigned to S. rehderiana provided convincing evidence that spontaneous interspecific hybridization occurred extensively in the living garden collection we studied. Different patterns of pollen dispersal (predominantly short-distance vs. long-distance pollination) were observed between intra- and interspecific hybridization events in the garden. Pollen dispersal within the ex situ populations was not restricted by distance, as evidenced by a lack of significant correlations between the average effective pollen dispersal distance (δ) and the geographic distances (d1 and d2) between maternal and paternal trees. The interspecific pollen-dispersal distance ranged from 10 to 620.1 m (mean 294.4 m). Such extensive hybridization in ex situ collections could jeopardize the genetic integrity of endangered species and irrevocably contaminate the gene pool if such hybrids are used for reintroduction and restoration. We recommend strongly that measures be taken to minimize the genetic risks of this kind of hybridization, including establishing buffer zones in ex situ collections, manipulating flowering phenology, testing seed lots before use in reintroduction programs, and controlling pollination for seed purity.     

The Normative Dimension and Legal Meaning of Endangered and Recovery in the U.S. Endangered Species Act

Abstract:  The ethical, legal, and social significance of the U.S. Endangered Species Act of 1973 (ESA) is widely appreciated. Much of the significance of the act arises from the legal definitions that the act provides for the terms threatened species and endangered species. The meanings of these terms are important because they give legal meaning to the concept of a recovered species. Unfortunately, the meanings of these terms are often misapprehended and rarely subjected to formal analysis. We analyzed the legal meaning of recovered species and illustrate key points with details from "recovery" efforts for the gray wolf ( Canis lupus ). We focused on interpreting the phrase "significant portion of its range," which is part of the legal definition of endangered species. We argue that recovery and endangerment entail a fundamentally normative dimension (i.e., specifying conditions of endangerment) and a fundamentally scientific dimension (i.e., determining whether a species meets the conditions of endangerment). Specifying conditions for endangerment is largely normative because it judges risks of extinction to be either acceptable or unacceptable. Like many other laws that specify what is unacceptable, the ESA largely specifies the conditions that constitute unacceptable extinction risk. The ESA specifies unacceptable risks of extinction by defining endangered species in terms of the portion of a species' range over which a species is "in danger of extinction." Our analysis indicated that (1) legal recovery entails much more than the scientific notion of population viability, (2) most efforts to recover endangered species are grossly inadequate, and (3) many unlisted species meet the legal definition of an endangered or threatened species.     

Hybridization,agency discretion,and implementation of the U.S. Endangered Species Act

The U.S. Endangered Species Act (ESA) requires that the “best available scientific and commercial data” be used to protect imperiled species from extinction and preserve biodiversity. However, it does not provide specific guidance on how to apply this mandate. Scientific data can be uncertain and controversial, particularly regarding species delineation and hybridization issues. The U.S. Fish and Wildlife Service (FWS) had an evolving hybrid policy to guide protection decisions for individuals of hybrid origin. Currently, this policy is in limbo because it resulted in several controversial conservation decisions in the past. Biologists from FWS must interpret and apply the best available science to their recommendations and likely use considerable discretion in making recommendations for what species to list, how to define those species, and how to recover them. We used semistructured interviews to collect data on FWS biologists’ use of discretion to make recommendations for listed species with hybridization issues. These biologists had a large amount of discretion to determine the best available science and how to interpret it but generally deferred to the scientific consensus on the taxonomic status of an organism. Respondents viewed hybridization primarily as a problem in the context of the ESA, although biologists who had experience with hybridization issues were more likely to describe it in more nuanced terms. Many interviewees expressed a desire to continue the current case‐by‐case approach for handling hybridization issues, but some wanted more guidance on procedures (i.e., a “flexible” hybrid policy). Field‐level information can provide critical insight into which policies are working (or not working) and why. The FWS biologists’ we interviewed had a high level of discretion, which greatly influenced ESA implementation, particularly in the context of hybridization.     

Bioactivity,adsorption and persistence of pretilachlor in paddy field soils

The effects of environmental factors on bioactivity, adsorption and persistence of pretilachlor were studied in the laboratory and greenhouse using cucumber (Cucumis sativus L.) as the bioassay species. The three soils studied viz. Bernam, Selangor and Sabrang series were chosen for their different characteristics. The half‐life of pretilachlor decreased from 10.24 to 4.90 days as temperature increased from 25°C to 35°C in the Selangor Series soil and from 10.86 to 7.63 days in the Bernam Series soil at 60% field capacity. At the same moisture level, an increase of temperature from 25°C to 35°C also reduced the half‐life of pretilachlor in Sabrang soil from 8.87 to 2.59 days. The half‐life of pretilachlor also decreased with increasing moisture levels in Selangor and Sabrang series but not in Bernam series soils. The greatest adsorption of pretilachlor was observed in Bernam series, followed by Selangor and Sabrang series. No phytotoxic residue of pretilachlor was detected in the supernatant after 10 h incubation. Since the residue was strongly adsorbed in Bernam series, its biological activity was less than in the other soils studied.     

漓江流域红壤区生态恢复过程中植被结构动态和生物量变化

利用时空替代原理,选取漓江流域红壤区退化生态系统恢复过程中具有代表性的草丛、灌丛、针叶林、针阔混交林、常绿阔叶林5个阶段作为演替序列,研究自然恢复过程中各演替阶段的植被结构动态和生物量变化。结果表明：随着草丛→灌丛→针叶林→针阔混交林→次生常绿阔叶林正向演替的进行,在未形成成熟而稳定的顶极群落之前,物种丰富度、物种多样性指数、植被生物量及生产力都呈增大趋势。退化群落通过自然恢复总是向着结构更复杂、更完善的方向发展。根据恢复过程中植被的动态变化规律,提出了一些人工促进植被恢复的建议．     

松花江水质因子分析及动态变化

松花江的水质一直受到各方的关注,尤其是在80年代末到90年代初.大多数的研究都关注重金属、有机有毒污染物等主要污染物的源、汇、归宿以及生态效应.然而,这些研究通常只考虑一个或几个独立的水质指标,多个指标的联合效应则很少研究.文章在监测数据的基础上,对松花江水质运用因子分析方法进行了研究.利用因子分析方法可以综合地考虑每个监测断面上的各个监测指标在不同水文期的变化.分析结果表明,松花江的主要污染物是来自非点源的氮源污染物,且其水质在不同的水文期是不同的.这一结果也表明,因子分析方法在分析水质动态变化上是综合有效的.     

Feasibility of metabolic parameter estimation in pharmacokinetic models of carbon tetrachloride exposure in rats1

Carbon tetrachloride (CCl₄) is a toxic chemical that was once used in degreasers and detergents, and some remnants of the chemical may be present in the water supply. Physiologically-based pharmacokinetic (PBPK) modeling can assist in understanding resulting internal doses of CCl₄ after exposure, but the pharmacokinetic parameters describing the metabolism of CCl₄ are not well characterized. The goal of this study was to provide insights into how to more accurately estimate these values in rats using PBPK modeling and data from previous studies. Three different PBPK models were constructed to describe CCl₄ exposure in rats via inhalation, oral ingestion, and venous injection. Each of these models was compared to data, and sensitivity analysis was performed for each model to determine whether the available data could be used to accurately determine the metabolic parameters of interest. These parameter sensitivities were so low that optimization to the available data yielded physiologically unrealistic results. Model sensitivities were analyzed for different doses and routes of exposure in order to find experimental conditions that would allow for greater identifiability of the metabolic parameters. Data were simulated from these models at optimal conditions with varying levels of noise from a normal distribution. Optimizations were then performed to confirm that the original values could be obtained. The experiments developed are left as suggestions for investigators who wish to further pursue estimating these metabolic parameters.     

Sensitivity Analyses of Spatial Population Viability Analysis Models for Species at Risk and Habitat Conservation Planning

Abstract:  Population viability analysis (PVA) is an effective framework for modeling species- and habitat-recovery efforts, but uncertainty in parameter estimates and model structure can lead to unreliable predictions. Integrating complex and often uncertain information into spatial PVA models requires that comprehensive sensitivity analyses be applied to explore the influence of spatial and nonspatial parameters on model predictions. We reviewed 87 analyses of spatial demographic PVA models of plants and animals to identify common approaches to sensitivity analysis in recent publications. In contrast to best practices recommended in the broader modeling community, sensitivity analyses of spatial PVAs were typically ad hoc, inconsistent, and difficult to compare. Most studies applied local approaches to sensitivity analyses, but few varied multiple parameters simultaneously. A lack of standards for sensitivity analysis and reporting in spatial PVAs has the potential to compromise the ability to learn collectively from PVA results, accurately interpret results in cases where model relationships include nonlinearities and interactions, prioritize monitoring and management actions, and ensure conservation-planning decisions are robust to uncertainties in spatial and nonspatial parameters. Our review underscores the need to develop tools for global sensitivity analysis and apply these to spatial PVA.     

天津植被指数对气候因子响应的敏感性分析

探索植被覆盖与气候变化相互关系是全球环境变化研究领域的重要内容之一,研究特定区域植被对气候变化响应特征对植被重建和生态恢复具有重要意义。然而,目前植被对气候因子响应的敏感性研究还十分缺乏。利用1982—2003年8km×8km的NASA/GIMMS半月合成的归一化植被指数（NDVI）和同期气候数据,研究了天津地区NDVI对气候因子响应特征及其敏感性。结果表明：植被NDVI与气温及降水均有显著非线性正相关关系（P〈0.0001）;在半月平均气温低于0℃时,植被NDVI与气温没有显著性相关,而从气温高于0℃,一直到高于22℃,NDVI与气温的关系均达到显著性水平（P〈0.05）,但相关性是逐渐降低的;当半月平均气温高于23℃及以上时,NDVI与气温没有显著的相关关系（P〉0.05）;当半月降水量〉0mm时,NDVI与降水存在极显著正相关关系（P〈0.0001）,随着降水量的增加,相关关系减弱,在降水量大于50mm时,NDVI与降水没有显著相关关系（P〉0.05）;研究结果证实,天津地区植被指数对气候的响应存有明显的非线性特征,在低温和低降水量条件下植被的响应更为敏感,23℃和50mm分别是该地区影响植被生长的气温和降水阈值。结合1982—2003年逐半月气候条件分析发现,气温的影响主要是春、秋两季,而降水的影响主要表现在春、秋及夏初。     

Population frequencies of alternative male phenotypes in tree lizards: geographic variation and common-garden rearing studies

Tree lizards (Urosaurus ornatus) vary in throat fan (dewlap) color. Earlier, we described five dewlap types (Orange, Orange-Blue, Yellow, Yellow-Blue, and Blue), and reported that only males had blue in the dewlap and that presence or absence of a discrete blue patch was correlated with male alternative reproductive phenotypes in a central Arizona population. Here, with a modified scheme characterizing two dewlap elements, background color (orange, yellow, blue) and blue patch occurrence, we assessed: (1) sexual, annual, and geographic variation in the frequencies of dewlap elements; (2) simple habitat correlates; and (3) the effects of laboratory rearing regime on dewlap type. Within a population, frequencies of males and females expressing orange or yellow backgrounds did not differ, suggesting that control of background is similar in the sexes. Within several populations, frequencies of the dewlap elements did not differ across years (and probably generations), indicating that phenotype frequencies are relatively stable. Among five populations frequencies of background colors varied, as did frequencies of male types (blue patch present or absent). Dewlap frequencies did not correlate with habitat (boulders or mesquite trees), although few populations were sampled. In male and female offspring reared from eggs to sexual maturity in a common-garden laboratory study, background color frequencies in both sexes and blue patch frequencies in males differed among offspring from different populations. Offspring frequencies matched respective parental population frequencies. Results suggest that among-population variation in frequencies of the two dewlap elements are mediated by differences in genetics, in maternal effects, or both. Thus, differences in male behavior functionally linked to the blue patch also may be controlled by genetic or maternal effects. Received: 17 January 1997 / Accepted after revision: 30 August 1997     

南京老山国家森林公园朴树种群动态

运用相邻格子法对南京老山国家森林公园朴树(Celtis sinensis)种群(以下简称老山朴树种群)进行野外调查,以定量方法研究其种群结构特征。编制种群静态生命表,并绘制存活曲线、死亡率曲线、消失率曲线和4个生存函数曲线,同时结合时间序列预测模型研究老山朴树种群的数量动态。结果表明,种群各龄级个体数虽然存在波动,但整体呈增长趋势,存活曲线属DeeveyⅡ型,分别在第Ⅰ和第Ⅶ龄级出现2个死亡率高峰。第1个峰值的出现主要是由于种内竞争激烈,第2个峰值伴随种群进入生理死亡年龄而出现。生存分析结果表明,朴树种群至第Ⅵ龄级时,生存率仅为0.5%,累计死亡率高达99.5%;危险率曲线与死亡率和消失率曲线变化情况基本一致,反映朴树种群生长发育过程具有前期薄弱、中期稳定、后期衰退的特点。时间序列预测结果表明,在未来的2～6 a内,老山朴树种群呈增长趋势。对幼苗及幼林进行人工抚育管理将有助于老山朴树种群的天然更新。     

Phytotoxicity and persistence of metribuzin residues in black soil

A bioassay procedure based on the root and shoot growth of cucumber and sorghum were used to study the phytotoxicity, as affected by varying the concentration of metribuzin, and persistence of metribuzin residues in soil. Sorghum and cucumber were found to be very susceptible test plant species to metribuzin. It was found that the persistence and phytotoxicity increased with increasing rate of application of metribuzin, and the relationship between herbicide concentration and phytotoxicity was best described by a quadratic equation. Sorghum and cucumber plants emerged as very sensitive new bioassay plants for metribuzin and could detect residues even at 0.010 and 0.046?ppm in the post harvest soil of potato crop.     

松嫩草甸不同退化程度生境土壤磷素动态研究

对松嫩草甸不同退化程度生境的几种代表植物群落土壤磷素状况的研究表明,各群落相同土层的全磷含量没有显著的差异,说明土壤磷库具有较强的弹性,土壤退化落后于地上植物群落的退化.各群落土壤全磷的季节变化相似,均经历迅速累积,达到峰值后下降,之后又有一个缓慢积累的过程.羊草、寸草苔和碱茅群落全磷含量随土层的加深而减少,虎尾草群落土壤全磷聚集于10~20cm土层.随退化程度的加重,土壤速效磷含量增加,虎尾草群落土壤速效磷占全磷的比重最高(2.8%),表明退化生境植物群落对速效磷素的利用并不充分.各群落土壤微生物量磷含量均高于速效磷含量,其季节动态均为单峰曲线,峰值出现在8月.虎尾草群落土壤微生物量磷在10~20cm的土层最多,其他群落土壤微生物量磷在0~10cm土层的含量最多.灰色分析的结果表明,土壤速效磷的形成主要受到土壤养分,尤其是碳、氮养分的影响;而土壤温度、水分状况、酸碱状况和盐化程度等因素对土壤微生物量磷的影响较强.图2表3参26     

兰州市郊红砂种群数量动态与分布格局

对兰州市南北两山天然分布的红砂种群数量动态和空间分布格局进行研究。利用地径回归得到红砂种群年龄结构,编制静态生命表,进行生存分析及谱分析,计算红砂种群年龄结构动态指数,以揭示种群数量动态特征;采用扩散系数、负二项指数、平均拥挤度、聚块性指数、扩散型指数、丛生指数、Cassie指数和Green指数8个分布指标判断红砂种群时空尺度上的格局类型。结果表明,南北两山红砂种群密度、盖度适宜,动态指数均大于0,呈现增长型,并存在明显的周期性;种群以中幼龄植株为主体,各龄级的死亡率基本平稳,但在第Ⅱ过渡到第Ⅲ龄级时,出现死亡高峰,存活曲线趋于Deevey-Ⅲ型。种群时空异质性明显,阳坡的红砂种群呈现聚集分布,阴坡则多呈现均匀分布;不同发育阶段红砂种群分布格局呈现明显递变规律,幼龄阶段聚集度高,随着年龄增大,聚集性大幅减弱。     

Sex-specific reproductive behaviours and paternity in free-ranging Barbary macaques (Macaca sylvanus)

In a wide variety of species, male reproductive success is determined by contest for access to females. Among multi-male primate groups, however, factors in addition to male competitive ability may also influence paternity outcome, although their exact nature and force is still largely unclear. Here, we have investigated in a group of free-ranging Barbary macaques whether paternity is determined on the pre- or postcopulatory level and how male competitive ability and female direct mate choice during the female fertile phase are related to male reproductive success. Behavioural observations were combined with faecal hormone analysis for timing of the fertile phase (13 cycles, 8 females) and genetic paternity analysis (n = 12). During the fertile phase, complete monopolisation of females did not occur. Females were consorted for only 49% of observation time, and all females had ejaculatory copulations with several males. Thus, in all cases, paternity was determined on the postcopulatory level. More than 80% of infants were sired by high-ranking males, and this reproductive skew was related to both, male competitive ability and female direct mate choice as high-ranking males spent more time in consort with females than low-ranking males, and females solicited copulations mainly from dominant males. As most ejaculatory copulations were female-initiated, female direct mate choice appeared to have the highest impact on male reproductive success. However, female preference was not directly translated into paternity, as fathers were not preferred over non-fathers in terms of solicitation, consortship and mating behaviour. Collectively, our data show that in the Barbary macaque, both sexes significantly influence male mating success, but that sperm of several males generally compete within the female reproductive tract and that therefore paternity is determined by mechanisms operating at the postcopulatory level.