Ontogeny of head and caudal fin shape of an apex marine predator: The tiger shark (Galeocerdo cuvier)

How morphology changes with size can have profound effects on the life history and ecology of an animal. For apex predators that can impact higher level ecosystem processes, such changes may have consequences for other species. Tiger sharks (Galeocerdo cuvier) are an apex predator in tropical seas, and, as adults, are highly migratory. However, little is known about ontogenetic changes in their body form, especially in relation to two aspects of shape that influence locomotion (caudal fin) and feeding (head shape). We captured digital images of the heads and caudal fins of live tiger sharks from Southern Florida and the Bahamas ranging in body size (hence age), and quantified shape of each using elliptical Fourier analysis. This revealed changes in the shape of the head and caudal fin of tiger sharks across ontogeny. Smaller juvenile tiger sharks show an asymmetrical tail with the dorsal (upper) lobe being substantially larger than the ventral (lower) lobe, and transition to more symmetrical tail in larger adults, although the upper lobe remains relatively larger in adults. The heads of juvenile tiger sharks are more conical, which transition to relatively broader heads over ontogeny. We interpret these changes as a result of two ecological transitions. First, adult tiger sharks can undertake extensive migrations and a more symmetrical tail could be more efficient for swimming longer distances, although we did not test this possibility. Second, adult tiger sharks expand their diet to consume larger and more diverse prey with age (turtles, mammals, and elasmobranchs), which requires substantially greater bite area and force to process. In contrast, juvenile tiger sharks consume smaller prey, such as fishes, crustaceans, and invertebrates. Our data reveal significant morphological shifts in an apex predator, which could have effects for other species that tiger sharks consume and interact with. J. Morphol. 277:556–564, 2016. © 2016 Wiley Periodicals, Inc.     

基于集合经验模态分解去趋势的水分利用效率对气候变化响应的高程分异——以“21世纪海上丝绸之路”沿线省份为例

水分利用效率(WUE)是表征陆地碳-水循环耦合关系的重要指标，但其对气候变化响应的高程分异仍不清楚。通过集合经验模态分解(EEMD)去趋势和偏相关方法，以"21世纪海上丝绸之路"沿线省份为研究区，揭示WUE对气候变化的响应及其随高程的分异。研究结果表明：(1)研究区内WUE多年均值由中心向南北递减。不同植被类型的WUE多年均值由高到低依次为：常绿针叶林、混交林、常绿阔叶林、稀树灌木草地、耕地和城市建设用地。(2)51.11%的区域表现出均温与WUE的正相关；而81.46%地区表明温差的扩大会使得WUE增加；有近一半的研究区表明最高温的升高有利于提高WUE，而最低温的作用则相反；有67.99%的区域表明降水增多反而会导致WUE的减少。(3)在大多数土地覆盖类型，日温差和最低温主要与WUE呈正相关，而最高温和降水主要与WUE呈负相关。在常绿针叶林、耕地和城市建设用地，日均温与WUE呈负相关。在其他三种植被类型下则呈正相关。(4)在低海拔地区，均温与WUE呈负相关而在中高海拔地区则转变为正相关关系。而最高温则正好相反。降水与WUE的负相关关系系数随高度的增加而不断加强，而温差和最低温与WUE的正相关关系也随高度的增加而剧烈波动增强。     

Application of the phosphomannose-isomerase/mannose selection system in the Agrobacterium-mediated transformation of Lonicera hypoglauca Miq.

Journal of Plant Biochemistry and Biotechnology - The dried buds of Lonicera hypoglauca Miq. have antipyretic, antidotal and anti-inflammatory properties and as Flos lonicerae are widely used in...     

A generic algorithm for finding restriction sites within DNA sequences

This paper describes a generic algorithm for finding restrictionsites within DNA sequences. The ‘genericity’ ofthe algorithm is made possible through the use of set theory.Basic elements of DNA sequences, i.e. nucleotides (bases), arerepresented in sets, and DNA sequences, whether specific, ambiguousor even protein-coding, are represented as sequences of thosesets. The set intersection operation demonstrates its abilityto perform pattern-matching correctly on various DNA sequences.The performance analysis showed that the degree of complexityof the pattern matching is reduced from exponential to linear.An example is given to show the actual and potential restrictionsites, derived by the generic algorithm, in the DNA sequencetemplate coding for a synthetic calmodulin. Received on October 2, 1990; accepted on December 18, 1990     

气候变化和人类活动对中国北方旱区植被变绿的定量贡献

气候变化和大规模的生态恢复使中国北方旱区植被发生了显著变化，量化气候变化和人类活动对植被动态的相对贡献，对于旱区生态系统管理和应对未来气候变化具有重要意义。目前，中国北方旱区植被变化影响因素的时间动态（2000年大规模生态恢复工程实施前后）和空间异质性（沿干旱梯度）仍需进一步的定量研究。基于多源数据，采用趋势分析、偏相关分析和随机森林模型等方法，分析了1981-2018年中国北方旱区气候和植被的时空变化规律，量化了2000年前后气候变化和人类活动对植被动态的相对贡献并分析其在干旱梯度上的空间差异性。结果表明：（1）1981-2018年期间，中国北方旱区的叶面积指数（LAI）平均增加速率为（0.0037±0.0443） a^-1，且增加速率沿干旱梯度增大。2000年前仅10.46%（P<0.05）的地区显著变绿，而2000年后达到36.84%，且植被变绿主要归因于非树木植被。（2）2000年后降水对植被变绿的正效应在不同干旱梯度均增加，而在半干旱区和亚湿润干旱区，温度对植被变绿由正向促进转为负向抑制，而辐射在干旱区由负效应转向正效应。（3）2000年前后，气候变化均主导着植被的动态，贡献率分别为96.07%和73.72%，人类活动的贡献在2000年后进一步增强（从3.93%增加到26.28%），且沿着干旱梯度而增加，其中人类活动对植被变绿的贡献在半干旱地区增加最显著（+0.0289 m² m^-2 a^-1，P<0.05）。研究结果可为未来气候变化下中国北方旱区的植被恢复和可持续发展提供科学依据。