The modern theory of biological evolution: an expanded synthesis

In 1858, two naturalists, Charles Darwin and Alfred Russel Wallace, independently proposed natural selection as the basic mechanism responsible for the origin of new phenotypic variants and, ultimately, new species. A large body of evidence for this hypothesis was published in Darwins Origin of Species one year later, the appearance of which provoked other leading scientists like August Weismann to adopt and amplify Darwins perspective. Weismanns neo-Darwinian theory of evolution was further elaborated, most notably in a series of books by Theodosius Dobzhansky, Ernst Mayr, Julian Huxley and others. In this article we first summarize the history of life on Earth and provide recent evidence demonstrating that Darwins dilemma (the apparent missing Precambrian record of life) has been resolved. Next, the historical development and structure of the modern synthesis is described within the context of the following topics: paleobiology and rates of evolution, mass extinctions and species selection, macroevolution and punctuated equilibrium, sexual reproduction and recombination, sexual selection and altruism, endosymbiosis and eukaryotic cell evolution, evolutionary developmental biology, phenotypic plasticity, epigenetic inheritance and molecular evolution, experimental bacterial evolution, and computer simulations (in silico evolution of digital organisms). In addition, we discuss the expansion of the modern synthesis, embracing all branches of scientific disciplines. It is concluded that the basic tenets of the synthetic theory have survived, but in modified form. These sub-theories require continued elaboration, particularly in light of molecular biology, to answer open-ended questions concerning the mechanisms of evolution in all five kingdoms of life.Dedicated to Prof. Dr. Dr. hc mult. Ernst Mayr on the occasion of his 100th birthdayThis revised version was published online in March 2004, with corrections to the caption of Figure 6.     

当地资源管理中多学科冲突分析和冲突减缓

在瑞典的研究项目"海岸带可持续管理"中,迄今已完成了几项冲突研究.鉴于这些研究的详细结果是分别发表的,本文综述这些冲突研究的重要成果,以及总结和概要讨论海岸带可持续管理资源和冲突研究的方法和主要成果.在关于环境和资源利用冲突的多学科和理论上分析以后,提出了海岸带可持续管理中所使用的方法,即相关利益方和冲突的结合分析.可归纳为以下主要4点:①绘制诸利益相关者及其利益图;②分析所有冲突;③研制减缓冲突和与利益相关者合作的方法;④把这些内容综合到一个系统之下,以便进行自然资源管理.在瑞典东、西海岸已经开展了一些资源利用冲突的范例研究,包括沿岸渔业、贻贝养殖、海岸带规划及具体的冲突,例如种群保护(海豹)和沿岸渔业之间冲突.研究人员既作为专家也作为冲突当事方参与.在冲突研究中,科学家作为利益相关者其作用值得特别注意.冲突管理不仅是为了解决目前的冲突,而且还作为资源综合管理系统的一部分,其中可开展知识转让;建立制度;科学、政治和行政等部门共同学习;以及科学家和资源用户之间合作.     

Activities of alkaline phosphatase in first trimester chorion biopsy tissue

We have determined the activity of alkaline phosphatase in chorionic villous tissue obtained in the first trimester of pregnancy, in order to obtain the normal range of values as a prerequisite for application to the prenatal diagnosis of the rare bone disease hypophosphatasia. The activities found were a combination of intestinal and liver/bone/kidney types; traces of placental type were present in only one sample.     

Hopanoid Biosynthesis and Function in Bacteria

   Hopanoids are pentacyclic triterpenoid lipids occurring in bacteria. They are synthesized from isopentenyl units which are formed in a new biosynthetic route leading to isopentenyl diphosphate. Six C₅ units are joined to form squalene, the immediate precursor in hopanoid synthesis. In a highly complex cyclization reaction that shares considerable similarities with that of oxidosqualene to sterols, the hopane skeleton is formed from squalene by the squalene-hopene cyclase. Recent elucidation of the X-ray structure of this membrane-bound cyclase has shed some light on the properties of this unusual enzyme. The active site is located in a cavity within the enzyme. The squalene substrate diffuses through a channel structure from the membrane into this cavity and is there transformed into hopene. Polar side chains are attached to hopene resulting in the amphiphilic molecular structure of many hopanoids. These hopanoids are membrane components involved in regulating membrane fluidity and stability. However, the many structural variants of hopanoids indicate that they may have other interesting but as yet unknown functions.