The effects of size-selective fisheries on the stock dynamics of and sperm limitation in sex-changing fish

Fisheries models have traditionally focused on patterns of growth, fecundity, and survival of fish. However, reproductive rates are the outcome of a variety of interconnected factors such as life-history strategies, mating patterns, population sex ratio, social interactions, and individual fecundity and fertility. Behaviorally appropriate models are necessary to understand stock dynamics and predict the success of management strategies. Protogynous sex-changing fish present a challenge for management because size-selective fisheries can drastically reduce reproductive rates. We present a general framework using an individual-based simulation model to determine the effect of life-history pattern, sperm production, mating system, and management strategy on stock dynamics. We apply this general approach to the specific question of how size-selective fisheries that remove mainly males will impact the stock dynamics of a protogynous population with fixed sex change compared to an otherwise identical dioecious population. In this dioecious population, we kept all aspects of the stock constant except for the pattern of sex determination (i.e. whether the species changes sex or is dioecious). Protogynous stocks with fixed sex change are predicted to be very sensitive to the size-selective fishing pattern. If all male size classes are fished, protogynous populations are predicted to crash even at relatively low fishing mortality. When some male size classes escape fishing, we predict that the mean population size of sex-changing stocks will decrease proportionally less than the mean population size of dioecious species experiencing the same fishing mortality. For protogynous species, spawning-per-recruit measures that ignore fertilization rates are not good indicators of the impact of fishing on the population. Decreased mating aggregation size is predicted to lead to an increased effect of sperm limitation at constant fishing mortality and effort. Marine protected areas have the potential to mitigate some effects of fishing on sperm limitation in sex-changing populations.

Life history of South African snoek, Thyrsites atun (Pisces: Gempylidae): a pelagic predator of the Benguela ecosystem

Snoek (Thyrsites atun) is a valuable commercial species and an important predator of small pelagic fishes in the Benguela ecosystem. The South African population attains 50% sexual maturity at a fork length of ca.73.0 cm (3 years). Spawning occurs offshore during winter−spring, along the shelf break (150–400 m) of the western Agulhas Bank and the South African west coast. Prevailing currents transport eggs and larvae to a primary nursery ground north of Cape Columbine and to a secondary nursery area to the east of Danger Point; both shallower than 150 m. Juveniles remain on the nursery grounds until maturity, growing to between 33 and 44 cm in the first year (3.25 cm/month). Onshore– offshore distribution (between 5- and 150-m isobaths) of juveniles is deter-mined largely by prey availability and includes a seasonal inshore migration in autumn in response to clupeoid recruitment. Adults are found through-out the distribution range of the species, and although they move offshore to spawn—there is some southward dispersion as the spawning season progresses—longshore movement is apparently random and without a seasonal basis. Relative condition of both sexes declined dramatically with the onset of spawning. Mesenteric fat loss was, however, higher in females, despite a greater rate of prey consumption. Spatial differences in sex ratios and indices of prey consumption suggest that females on the west coast move inshore to feed between spawning events, but that those found farther south along the western Agulhas Bank remain on the spawning ground throughout the spawning season. This regional difference in female behavior is attributed to higher offshore abundance of clupeid prey on the western Agulhas Bank, as determined from both diet and rates of prey consumption.

Modelling the long-term sustainability of indigenous hunting in Manu National Park, Peru: landscape-scale management implications for Amazonia

P> Widespread hunting throughout Amazonia threatens the persistence of large primates and other vertebrates. Most studies have used models of limited validity and restricted spatial and temporal scales to assess the sustainability. We use human-demographi

构建度量区间时序逻辑的时间自动机

实时系统的安全性至关重要，使用模型检测工具对其进行形式化分析是提高 其安全性的重要手段。我们已有的实时系统模型检测工具CTAV 目前可以验证 LTL 描述的性质。本文工作的最终目的是让CTAV 能够验证实时时序逻辑，即， 使得CTAV 同样可以直接验证由实时时序逻辑描述的连续时间域上的实时性质。 度量区间时序逻辑MITL 是常用的一种关于实时系统的性质规范语言。已有 不少文献讨论过MITL 到时间Büchi 自动机的转换，但由于过程较复杂，大多数 仅限于理论研究，并没有与时间Büchi 自动机的空性判定过程结合成为一个可用 的关于MITL 的模型检测工具。 为了开发可用的关于MITL 性质的模型检测工具，本文采用与CTAV 中待验 证系统模型一致的pointwise 语义模型，选取了MITL 的一个可以较高效的进行模型检测的子类——MITL≤/<。在表达能力方面，这个子集能够描述实时系统模 型检测实际过程中常见的实时性质。 本文给出了将MITL≤/<公式转化为等价的基于迁移的扩展时间Büchi 自动机 的算法过程，并讨论了转化中逻辑公式重写规则的正确性和完备性问题。基于迁 移的扩展时间Büchi 自动机是时间Büchi 自动机的一种变体。二者最主要的区别在于它们采用了不同类型的Büchi 接受条件。文中给出的构造算法是将原先应用于非实时领域的Tableau 方法扩展调整，并应用于实时连续领域。Tableau 方法的关键之一是公式重写规则。而为了保证结果自动机仅存在有限多个状态，在重写规则中定义不动子公式是至关重要的。本文给出的在pointwise 语义模型下的公式重写规则，借用了此前在continuous 语义模型下已有的将时钟变量作为时序算子的约束直接引入公式中来保证重写规则中存在不动子公式的思想，并对其进行了修改，使原先性质自动机的时钟递减变为时钟递增，与系统自动机中的时钟行走方式一致。这省去了下一步将性质自动机和系统自动机相乘判空时，因为时钟行走方式不一致而引起的麻烦。另外，本文将MITL≤/<中的某些公式扩展为包含时钟约束的新的公式。这样，在定义重写公式时，不仅保证重写规则中存在不动子公式，也保证结果自动的前进性。 本文还根据构造算法实现了转化工具MITLCon。与Marc Geilen 和Dennis Dames 实现的逻辑转化工具相比，MITLCon 显著地减少了结果自动机节点和迁 移的数量，从而降低了结果自动机的大小，有利于进一步的模型检测过程。

金丝桃素体外抗高致病性猪生殖与呼吸综合征病毒活性的研究

为研究金丝桃素体外对高致病性猪生殖与呼吸综合征病毒(PRRSV)活性的影响,以Marc-145细胞培养增殖的PRRSV为研究对象,通过噻唑蓝(MTT)比色法和观察细胞病变效应(CPE),测定吸光度值(D490nm)和半数细胞感染量(TCID50),以细胞存活率、病毒抑制率和TCID50为指标,评价不同剂量的金丝桃素体外抑制PRRSV活性的效应,并通过改变加药方式(同时、感染前、感染后给药),探讨其抗PRRSV的作用机制。结果表明,在PRRSV感染的同时加入金丝桃素,其细胞存活率和对PRRSV的抑制率略有升高,与PRRSV对照组和拉米夫定对照组相比,均有显著性差异(P<0.01)。在PRRSV感染前和感染后加入金丝桃素,其细胞存活率和对PRRSV的抑制率明显升高,且随药物浓度的增加而上升,与PRRSV对照组相比,有显著性差异(P<0.01),与拉米夫定对照组相比无统计学意义(P>0.05)。金丝桃素可使PRRSV的TCID50从6.1下降至4.15。证实,金丝桃素具有多环节体外抗PRRSV效应;不同浓度的金丝桃素表现出不同的抗PRRSV活性,并呈现剂量依赖关系。

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 May 2009-31 July 2009

This article documents the addition of 512 microsatellite marker loci and nine pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Alcippe morrisonia morrisonia, Bashania fangiana, Bashania fargesii, Chaetodon vagabundus, Colletes floralis, Coluber constrictor flaviventris, Coptotermes gestroi, Crotophaga major, Cyprinella lutrensis, Danaus plexippus, Fagus grandifolia, Falco tinnunculus, Fletcherimyia fletcheri, Hydrilla verticillata, Laterallus jamaicensis coturniculus, Leavenworthia alabamica, Marmosops incanus, Miichthys miiuy, Nasua nasua, Noturus exilis, Odontesthes bonariensis, Quadrula fragosa, Pinctada maxima, Pseudaletia separata, Pseudoperonospora cubensis, Podocarpus elatus, Portunus trituberculatus, Rhagoletis cerasi, Rhinella schneideri, Sarracenia alata, Skeletonema marinoi, Sminthurus viridis, Syngnathus abaster, Uroteuthis (Photololigo) chinensis, Verticillium dahliae, Wasmannia auropunctata, and Zygochlamys patagonica. These loci were cross-tested on the following species: Chaetodon baronessa, Falco columbarius, Falco eleonorae, Falco naumanni, Falco peregrinus, Falco subbuteo, Didelphis aurita, Gracilinanus microtarsus, Marmosops paulensis, Monodelphis Americana, Odontesthes hatcheri, Podocarpus grayi, Podocarpus lawrencei, Podocarpus smithii, Portunus pelagicus, Syngnathus acus, Syngnathus typhle,Uroteuthis (Photololigo) edulis, Uroteuthis (Photololigo) duvauceli and Verticillium albo-atrum. This article also documents the addition of nine sequencing primer pairs and sixteen allele specific primers or probes for Oncorhynchus mykiss and Oncorhynchus tshawytscha; these primers and assays were cross-tested in both species.

Dynamically Stable Legged Locomotion (September 1985-Septembers1989)

This report documents our work in exploring active balance for dynamic legged systems for the period from September 1985 through September 1989. The purpose of this research is to build a foundation of knowledge that can lead both to the construction of useful legged vehicles and to a better understanding of animal locomotion. In this report we focus on the control of biped locomotion, the use of terrain footholds, running at high speed, biped gymnastics, symmetry in running, and the mechanical design of articulated legs.