资源限制与发展停滞：传统社会的生态学分析

资源限制与发展停滞：传统社会的生态学分析王建革（复旦大学历史地理研究所,上海２００４３３）ＲｅｓｏｕｒｃｅｓＬｉｍｉｔａｔｉｏｎａｎｄＳｌｏｗＤｅｖｅｌｏｐｍｅｎｔ：ＡｎＥｃｏｌｏｇｉｃａｌＡｎａｌｙｓｉｓｏｆＴｒａｄｉｔｉｏｎａｌＳｏｃｉｅｔｙ．Ｗ...     

Autotoxicity: Concept,Organisms, and Ecological Significance

The present review deals with the phenomenon of autotoxicity — a type of intraspecific allelopathy, where a plant species inhibits the growth of its own kind through the release of toxic chemicals into the environment. This phenomenon has been reported to occur in a number of weeds and crop plants in agroecosystem and wastelands causing the soil sickness. Besides, it plays a significant role in the orchards (of apple, pear, grapes, etc.) where it is the major reason of the replant problem, natural forests and coffee and tea plantations causing the regeneration problems. Not only the higher plants, but even some ferns and algae are also reported to show this phenomenon. Some plants have even developed extensive mechanisms to overcome this phenomenon, whereas the others have adapted to it by making structural and ecological changes providing to them a competitive ecological advantage over the others. Although autotoxicity is a natural phenomena providing selective benefit to the plant, yet the chemicals responsible for this have good potential for weed and pest management.     

Feeding Strategies in Marine Snakes: An Analysis of Evolutionary, Morphological, Behavioral and Ecological Relationships

Analysis of 1,063 stomach contents from 39 species of sea snakesindicates that about one-third of the shallow, warm, marine,Indo-Australian fish families are preyed upon by sea snakes.Families of eels and gobies are taken by the greatest numbersof snake species. Most species of sea snakes feed on fish familieswhose members are relatively sedentary, dwelling along the bottom,within burrows or reef crevices. With one exception, a fishegg-eating specialization found uniquely in the Aipysurus-Emydocephaluslineage, the dietary habits of sea snakes cannot be categorizedaccording to the snakes' three phylogenetic lineages. Eels,mullet-like, rabbitfish-like and goby-like fish forms are takenby all three lineages. Two or three snake species are generalists,and numerous ones specialize on eels, goby-like fish or catfish.There are differences among sea snake species in the relationshipbetween snake neck girth and the maximum diameter of the prey;in the relationships of both snake gape measurements and fanglength, to the type of prey taken; and in the relationship ofsnake shape and body proportions to the prey selected. Severalmodes of feeding have been observed among sea snakes: feedingin nooks and crannies in the bottom or in reefs, cruising nearthe bottom, and feeding in drift lines. Analysis of percentdigestion of stomach contents and projections backward to thetimes of prey capture provides evidence for feeding periodicity.The greatest amount of diet overlap is for two species of seasnakes which do not both occur at the same locality. Where speciesdo co-occur, diet overlap index values are lower. The numbersof species present as well as their relative abundances varyamong localities as does the relative importance of generalists,eel-eaters, egg-eaters and other specialized feeders.     

World Ecological Degradation: Accumulation, Urbanization, and Deforestation, 3000 B.C.–A.D. 2000.

World Ecological Degradation: Accumulation, Urbanization, and Deforestation, 3000 B.C.–A.D. 2000. Sing C. Chew. Walnut Creek, CA: Altamira Press, 2001. 217 pp.     

家庭生态农场的氮素营养生产分析

引言土地的沙漠化也许是人类文明进程所付出的最沉重代价。我国北方干旱地区是一个巨大的潜在“沙漠化温床”,巳沙化土地达3.34×     

Insect Transgenesis: Mechanisms,Applications, and Ecological Safety

Abstract

Glycosylation is considered to be an important reaction for the chemical modification of compounds with useful biological activities. Glycoside hydrolases are biotechnologically attractive enzymes which can be used in synthetic reactions for assembling glycosidic linkages with absolute stereoselectivity at an anomeric centre. Most of these enzymes are commercially available but there is great interest in the search for new biocatalysts with original catalytic characteristics. The marine environment has shown to be a very interesting source for new glycosyl hydrolases for both hydrolytic and synthetic aspects. In particular, Aplysia fasciata a marine herbivorous mollusc has been shown to be a potent producer of a library of glycoside hydrolases applied to the synthesis of glycosidic bonds. The impressive assortment of glycosidases in marine organisms clearly indicates that the potential biodiversity of these enzymes is still largely unexplored and that potential applications of biocatalysts from the sea will increase in the near future.     

Ecological speciation in sympatric palms: 1. Gene expression,selection and pleiotropy

Ecological speciation requires divergent selection, reproductive isolation and a genetic mechanism to link the two. We examined the role of gene expression and coding sequence evolution in this process using two species of Howea palms that have diverged sympatrically on Lord Howe Island, Australia. These palms are associated with distinct soil types and have displaced flowering times, representing an ideal candidate for ecological speciation. We generated large amounts of RNA‐Seq data from multiple individuals and tissue types collected on the island from each of the two species. We found that differentially expressed loci as well as those with divergent coding sequences between Howea species were associated with known ecological and phenotypic differences, including response to salinity, drought, pH and flowering time. From these loci, we identified potential ‘ecological speciation genes’ and further validate their effect on flowering time by knocking out orthologous loci in a model plant species. Finally, we put forward six plausible ecological speciation loci, providing support for the hypothesis that pleiotropy could help to overcome the antagonism between selection and recombination during speciation with gene flow.