994 resultados para 146-889A
Resumo:
Western Atlantic synodontid species were studied as part of an ongoing effort to reanalyze Caribbean shorefish diversity. A neighbor-joining tree constructed from cytochrome c oxidase I (COI) data revealed 2 highly divergent genetic lineages within both Synodus intermedius (Agassiz, 1829) (Sand Diver) and S. foetens (Linnaeus, 1766) (Inshore Lizardfish). A new species, Synodus macrostigmus, is described for one of the S. intermedius lineages. Synodus macrostigmus and S. intermedius differ in number of lateral-line scales, caudal pigmentation, size of the scapular blotch, and shape of the anterior-nostril flap. Synodus macrostigmus and S. intermedius have overlapping geographic and depth distributions, but S. macrostigmus generally inhabits deeper water (>28 m) than does S. intermedius and is known only from coastal waters of the southeastern United States and the Gulf of Mexico, in contrast to those areas and the Caribbean for S. intermedius. Synodus bondi Fowler, 1939, is resurrected from the synonymy of S. foetens for one of the S. foetens genetic lineages. The 2 species differ in length and shape of the snout, number of anal-fin rays, and shape of the anterior-nostril flap. Synodus bondi and S. foetens co-occur in the central Caribbean, but S. bondi otherwise has a more southerly distribution than does S. foetens. Redescriptions are provided for S. intermedius, S. foetens, and S. bondi. Neotypes are designated for S. intermedius and S. foetens. A revised key to Synodus species in the western Atlantic is presented.
Resumo:
原产于亚马逊河流域的水生植物凤眼莲(Eichhornia crassipes)在花部结构上有三种花型(L、M和S),故其配殖系统(mating system)为典型的三型花柱(tristyly)。但在入侵地区,它却常只有M和L两种花型,其中尤以M型占据绝对优势,使有性繁殖水平大为下降。为了解释凤眼莲在入侵过程中,花型频率为何发生变化以及该变化对其在入侵地的适应性进化上有何影响,作者在中国西南的两个居群中连续两年开展了野外生长和人工授粉实验,对比分析水面和泥地两类不同生境中M和L在克隆生长、生物量积累以及有性繁殖水平等方面的异同,并利用RAPD、 ISSR片段比较了具M型和L型花植物个体间的遗传变异水平。对三型花柱这一长期引人注目的遗传模式的分子位点也尝试了连锁片段的克隆和测序。 克隆生长的对比实验发现,在2004年,漂浮生长的M个体平均克隆分株数为25.37,L为21.20,前者显示较强的克隆生长能力(t=2.252, P< 0.05);2005年的实验再次证实M(每个个体19.83个分株)比L(每个个体15.53分株)表现出了显著较强的克隆优势(t=2.631,P<0.001)。M较L多产生克隆约24%。 但在岸边泥地上固着生长时,2004年L个体平均克隆分株为16.20,M 为10.17个分株。L表现出了更强的克隆生长能力(t=4.788,p<0.001),与漂浮生长状况下的情形恰恰相反,暗示M与L个体可能存在一定的生态位分化。这种分化可能是在入侵过程中形成的,也可能反映了原产地亚马孙流域旱涝交替造成的固着生长与漂浮生长交替发生的种内适应性。 生物量(干重)的对比分析发现,M个体在漂浮生长和固着生长的情况下都比L有着更高的生物量积累(漂浮生长实验:t=6.173,p<0.005(2004年);t=6.99,p<0.001(2005年)。固着生长实验:t=4.029,p<0.001)。生物量对凤眼莲的竞争和过冬有着一定的作用,因此较大的生物量积累可能是M个体在当地气候和环境中逐渐适应的一个结果。 有性繁殖的实验包括了实验个体的花序数与花朵数、自交与异交人工授粉的结实情况以及种子萌发率等方面的对比分析。结果表明,虽然M和L个体在花序数和花朵数上不存在显著差异,但是M个体在自交和异交的种子产量上比L略高,尤其是自交的种子产量,M显著高于L(M平均每个蒴果的自交种子产量为139.8,L为76.2)。以各100粒种子进行萌发实验,发现两花型之间在种子萌发率上不存在显著差异。对于M而言,其自交种子产量远大于异交种子产量 (139.8 vs. 93.3),且种子萌发率也略大于异交的种子萌发率(自交种子萌发率45.47%,异交种子萌发率 30.73%)。结合以上的实验结果,本文认为M基因型优势的形成可能与M个体与当地环境长期适应导致的生长与繁殖 上的优势有关。M的本地适应性是建立在特定的遗传背景上时,异交反而会破坏这种遗传组合,造成远交衰退。 对40个M和30个L个体进行20个RAPD引物和20个ISSR引物的遗传分析时发现,所有个体在RAPD表型上没有区别,但是在M中出现了3个ISSR表型,在L中出现了2个ISSR表型。本文还尝试利用RAPD技术扫描与三型花柱的遗传位点连锁的DNA片段。在146个RAPD随机引物中,初步发现两个候选片段,一个750bp,另一个2 000bp;已对它们进行了克隆、测序。 这些初步实验表明凤眼莲在我国的入侵可能伴随着基因型的差异表现和居群遗传分化,这种基因型的差异表现对该植物的成功入侵具有作用。其中,花型为M的个体的优势生长解释了该花型在中国分布区内的主导地位。推测该生长优势的遗传基础可能来源于基因组内较高的杂合子水平和在入侵地较长的适应历史,但最终结论尚有待进一步的实验证据。
Resumo:
To develop a portfolio of indicators and measures that could best measure changes in the social, economic, environmental and health dimensions of well-being in coastal counties we convened a group of experts March 8-9, 2011 in Charleston, SC, U.S.A. The region of interest was of the northern Gulf of Mexico, specifically, those coastal counties most impacted during the explosion and subsequent oil spill from the Macondo Prospect wellhead during the summer of 2010. Over the course of the two-day workshop participants moved through presentations and facilitated sessions to identify and prioritize potential indicators and measures deemed most valuable for capturing changes in well-being related to changes in or disruption of ecosystem services. The experts reached consensus on a list of indicators that are now being operationalized by NOAA researchers. The ultimate goal of this research project is to determine whether a meaningful set of social and economic indicators can be developed to document changes in well-being that occur as a result of changes in ecosystem services. The outcomes and outputs from the workshop that is the subject of this report helped us to identify high-quality indicators useful for measuring well-being.