Comparing Species Assemblages Via Species Accumulation Curves

Summary Comparing species assemblages given incidence‐based data is of importance in ecological studies, often done by a visual inspection of estimated species accumulation curves or by an ad hoc use of 95% pointwise confidence bands of these curves. It is shown that comparing species assemblages is a challenging problem. A χ² test is proposed. An adjustment using an eigenvalue decomposition is proposed to overcome computational difficulties. The bootstrap method is also suggested to approximate the distribution of the proposed test statistic. The eigenvalue adjusted (Eva) χ² test and the Eva‐bootstrap test are assessed by a simulation study. Both the Eva‐χ² and the Eva‐bootstrap tests are applied to a study that involves two woody seedling species assemblages.     

蜘蛛与蜘蛛、蜘蛛与猎物之间的信息联系机制

作为农林生态系统中首要的捕食性节肢动物的蜘蛛,只有单眼和听毛,并没有复眼和听器。因而在一定的距离之外,蜘蛛要高效、成功寻觅其理想的猎物,仅仅凭视觉、触觉、听觉均无法实现和完成这一功能。因此,蜘蛛的嗅觉即化学通信于蜘蛛种间和种内的信息联系中扮演着举足轻重的角色,现已有大量的研究用行为学的方法证明蜘蛛与猎物之间,蜘蛛与蜘蛛之间能够通过信息化学物质进行信息联系,但蜘蛛的嗅觉即化学信息素的释放与接收机制以及信息素的结构成份等方面的研究甚少,有待进一步深人。对蜘蛛与猎物之间,蜘蛛与蜘蛛之间的信息化学联系机制的研究进展做一综述。     

Species orthogonalization

We discuss the general formation of complementary behaviors, functions and forms in biological species competing for resources. We call orthogonalization the related processes on macro and micro-level of a self-organized formation of correlations in the species properties. Orthogonalization processes could be, for example, easily observed in sympatric speciation, as we show in numerical studies carried out with a new population equation. As a practical result, we find that the number of species is proportional to the effective richness of resources and depends on their history.     

Species monophyly

In biological systematics, as well as in the philosophy of biology, species and higher taxa are individuated through their unique evolutionary origin. This is taken by some authors to mean that monophyly is a (relational) property not only of higher taxa, but also of species. A species is said to originate through speciation, and to go extinct when it splits into two daughter species (or through terminal extinction). Its unique evolutionary origin is said to bestow identity on a species through time and change, and to render species names rigid designators. Species names are thus believed to function just like names of supraspecific taxa. However, large parts of the Web of Life are composed of species that do not have a unique evolutionary origin from a single population, lineage or stem-species. Further, monophyly is an ambiguous concept if it is defined simply in terms of 'unique evolutionary origin'. Disambiguating the concept by defining a monophyletic taxon as 'a taxon that includes the ancestor and all, and only, its descendant' renders monophyly inapplicable to species. At the heart of the problem lies a fundamental distinction between species and monophyletic taxa, where species form mutually exclusive reticulated systems, while higher taxa form inclusive hierarchical systems. Examples are given both at the species level and below to illustrate the problems that result from the application of the monophyly criterion to species. The conclusion is that the concepts of exclusivity and monophyly should be treated as non-overlapping: exclusivity marks out a species synchronistically, i.e. in the present time. Monophyly marks out clades (groups of species) diachronistically, i.e. within an historical dimension.     

Species Specific Flavone Glucuronides in Elodea Species

The flavonoid patterns of plants of Elodea canadensis, E. ernstae and E. nuttallii apigenin were investigated. The main flavonoids of E. canadensis are apeginin, luteolin and chrysoeriol 7-O-diglucuronides, of E. nuttalli apigenin and luteolin 7-O- diglucuronides, and of E. ernstae apigenin and luteonin 7-O-monoglucoronides. The qualitative stability of these flavonoid patterns is checked by chromatographic comparison of various populations from a wide area of the three species, it is shown that the flavonoid patterns are valuable criteria for the separation of these species.     

山东省的长肢林蛙种组物种

前人报道天津和山东有日本林蛙的分布,但也有学者表示怀疑。本文报道采集于山东徂徕山的该类物种。从成体量度和蝌蚪唇踟式来看,与现报道的镇海林蛙和峨眉林蛙有一定差异。该物种体型大小与峨眉林蛙相近似,唇齿式为1：2-2／111     

Species as individuals

There is no question that the constituents of cells and organisms are joined together by the part-whole relation. Genes are part of cells, and cells are part of organisms. Species taxa, however, have traditionally been conceived of, not as wholes with parts, but as classes with members. But why does the relation change abruptly from part-whole to class-membership above the level of organisms? Ghiselin, Hull and others have argued that it doesn't. Cells and organisms are cohesive mereological sums, and since species taxa are like cells and organisms in the relevant respects, they, too, are cohesive mereological sums. I provide further reasons in support of the thesis that species are mereological sums. I argue, moreover, that the advocate of this thesis is committed to a form of pluralism with respect to the species concept.