北京地区黑线仓鼠年龄鉴定及种群年龄组成的研究

鼠类种群年龄组成的研究是种群生态学的基础内容。种群年龄组成的变化,直接关系到鼠类数量的波动。黑线仓鼠(Cricetulus barabensis)是北京地区农田的主要害鼠之一,为探讨该鼠种在农田生态系统中的作用,并控制其危害,研究其种群年龄组成及变化是非常必要的。     

生态位态势理论与扩充假说

生态位态势理论,即从个体到生物圈,无论是自然还是社会中的生物单元都具有生态和势两个方面的属性,态是指生物的状态,是过去生长发育,学习,社会经济发展以及与环境相互和积累的结果;势是指生物单元对环境的现实影响力或支配力,始能量和物质变换的速率,生产力,生物增长率,经济增长率,占据新生境的能力,生物单元态的变化一般呈“Ｓ”型曲线,而势的变化则呈“钟”型曲线,特定生态系统中某生物单元的生态位即是该生物单元     

ON THE TITRATION OF BACTERIOPHAGE AND THE PARTICULATE HYPOTHESIS

1. The theory of the serial dilution method of titration of bacterio-phage has been worked out on the basis of the simple particulate hypothesis. 2. It has been shown that, if the dilution constant is .1, only about 60 per cent of parallel runs on the same solution should give the same end-point, the average being taken over a great number of titrations of each of a great variety of solutions. 3. The discrepancy between this figure, 60 per cent, and Dr. Bronfenbrenner''s estimate, 85 per cent, is considerable. 4. Inasmuch as the particulate hypothesis is well founded, no explanation of the discrepancy is suggested.     

黄胸鼠的年龄鉴定和种群年龄组成

本文经晶体干重法鉴定黄胸鼠的年龄,分析其种群年龄组成,并与其他年龄鉴定方法如体重法、体长法、臼齿磨损法进行了比较。     

北羌塘盆地中部笙根地区索瓦组上段的孢粉型化石组合及时代

报道北羌塘盆地笙根地区前人划分的上侏罗统索瓦组的上部发现了具有典型意义的、代表早白垩世的Dicheiropollis花粉。表明在该地区索瓦组上部是以前未能识别的下白垩统。根据该套地层中Dicheiropollis花粉的出现及孢粉组合中大量出现的Cyathidites和Classopollis,以及较为丰富的Gonyaulacysta jurassica与多类型沟鞭藻化石组合特征,确定索瓦组上部时代归属为早白垩世早期。这不仅为北羌塘盆地笙根地区早白垩世海相地层的存在提供了依据,而且为进一步分析和完善北羌塘中生代盆地演化史提供了有意义的线索。     

社鼠的年龄鉴定与种群年龄组成

年龄组成是种群的重要特征之一。分析年龄组成中不同时期各年龄组数量的比例,有助于了解种群数量变动的规律。寿振黄等(1959)以臼齿齿根的分岐与否和前后根的长度作为红背(鼠平)的年龄标准。罗泽珣(1963)和诸葛阳等(1959、1978)分别用臼齿磨损程度和体重来划分黑线姬鼠的年龄。国外有以晶体干重为依据分析年龄组成,如Lord(1959),Adamczewska-Andrzejewska(1972),Geurley(1975),Yabe(1979)等分别对白尾兔(Cottontail rabbit)、黑线姬鼠(Apodemus agrarius)2种田鼠(Microtus pinetorum和Microtus montanus)、和褐家鼠(Rattus norvegicus)进行了不少工作。     

广州地区中华按蚊生理年龄的组成

中华按蚊是我国平原地区的传疟媒介,研究中华按蚊的生态学,对于疟疾的流行病学及预防均具有重要的意义。生理年龄及生殖营养环的研究,不但可以进一步认识中华按蚊在自然界的一些生态学问题,更重要的是有助于分析其传疟的作用,作为防制的依据。     

THE AGE AND RELATIONSHIPS OF THE MAJOR ANIMAL PHYLA

Given the uncertainties in the fossil record and the paucity of informative morphological characters, there is still considerable uncertainty as to the phylogenetic affinities and times of origins of essentially all of the phyla of animals. A multilocus analysis of amino-acid sequence data for mitochondrial genes suggests that the major triploblast phyla began diverging approximately 630 million years ago. These results support the hypothesis that the so-called Cambrian radiation of animals actually initiated about 100 million years prior to the Cambrian, as the fossil evidence suggests. In addition, phylogenetic analysis supports the monophyly of animals, an early (~900 million years ago) branching off of the cnidarian lineage, the monophyly of deuterostomes and protostomes, and the inclusion of nematodes in the protostome lineage. The results of this study suggest that, with appropriate levels of taxon sampling and a focus on conserved regions of protein-coding sequence, complete mitochondrial genome analysis may be sufficiently powerful to elucidate the genealogical relationships of many of the animal phyla.     

INTRASPECIFIC VARIATION IN ANT SEX RATIOS AND THE TRIVERS-HARE HYPOTHESIS

We consider worker-controlled sex investments in eusocial Hymenoptera (ants in particular) and assume that relatedness asymmetry is variable among colonies and that workers are able to assess the relatedness asymmetry in their own colony. We predict that such “assessing” workers should maximize their inclusive fitness by specializing in the production of the sex to which they are relatively most related, i.e., colonies whose workers have a relatedness asymmetry below the population average should specialize in males, whereas colonies whose workers have a higher than average relatedness asymmetry should specialize in making females. Our argument yields the expectation that colony sex ratios will be bimodally distributed in ant populations where relatedness asymmetry is variable owing to multiple mating, worker reproduction, and/or polygyny. No such bimodality is expected, however, in ant species where relatedness asymmetry is known to be constant, or in cases where relatedness asymmetry is supposed to be irrelevant due to allospecific brood rearing under queen control, as in the slave-making ants. Comparative data on colony sex ratios in ants are reviewed to test the predictions. The data partly support our contentions, but are as yet insufficient to be considered as decisive evidence.     

南秦岭略阳地区略阳组牙形刺新材料及其时代意义

略阳组分布于南秦岭勉略缝合带附近,是略阳地区重要的岩石地层单元。本次研究在略阳灵岩寺南部剖面的略阳组获得牙形刺13枚,共识别出3属5种,包含2亚种和2未定种,分别为:Siphonodella homosimplex,Polygnathus communis communis,Po.inornatus inornatus,Po. sp.和Pseudopolygnathus sp.。该牙形刺组合可以与华南同时期牙形刺进行对比,时代为早石炭世杜内期早期,这为确定略阳组的下部层位的具体时代提供了新的牙形刺证据。略阳组中所产出的Si.homosimplex为华南地区浅水相牙形刺的典型代表,Po.inornatus inornatus广泛见于西欧的浅水相地层,这表明在早石炭世期间勉略地区为浅水碳酸盐岩台地沉积环境,且与华南地区生物区系存在紧密联系,同前人根据底栖生物化石研究得出的结论相一致。