Testing hypotheses in macroevolution

Experimental manipulation of microevolution (changes in frequency of heritable traits in populations) has shed much light on evolutionary processes. But many evolutionary processes occur on scales that are not amenable to experimental manipulation. Indeed, one of the reasons that macroevolution (changes in biodiversity over time, space and lineages) has sometimes been a controversial topic is that processes underlying the generation of biological diversity generally operate at scales that are not open to direct observation or manipulation. Macroevolutionary hypotheses can be tested by using them to generate predictions then asking whether observations from the biological world match those predictions. Each study that identifies significant correlations between evolutionary events, processes or outcomes can generate new predictions that can be further tested with different datasets, allowing a cumulative process that may narrow down on plausible explanations, or lead to rejection of other explanations as inconsistent or unsupported. A similar approach can be taken even for unique events, for example by comparing patterns in different regions, lineages, or time periods. I will illustrate the promise and pitfalls of these approaches using a range of examples, and discuss the problems of inferring causality from significant evolutionary associations.     

寄生传输中的抗干扰研究

本文讨论了寄生传输中干扰的特点及抗干扰的有效途径，给出了软件抗干扰的编码方式，可直接应用于系统的工程设计中。     

Two remarkable nematodes from sharks in Japan

Two species of nematodes, Acanthocheilus rotundatus (Rudolphi, 1819) and Metaleptus rabuka Machida, Ogawa and Okiyama, 1982, have been recorded from the stomach of Mustelus griseus Pietschmann and M. manazo Bleeker (Triakinidae, Carcharhiniformes) and from the intestine of Apristurus fedorovi Dolganov (Scyliorhinidae, Carcharhiniformes), respectively, from the North Pacific Ocean off Honshu, Japan. Both species are redescribed and their cephalic structures have been studied, for the first time, by scanning electron microscopy. A. fedorovi represents a new host record for M. rabuka. The morphology of M. rabuka, particularly the presence of a somewhat trilobed pseudolabia, an undivided oesophagus and the structure of the male caudal end, shows that it is necessary to transfer the monotypic genus Metaleptus Machida, Ogawa and Okiyama, 1982 from the Physalopteroidea to the Gnathostomatoidea, where a new subfamily, Metaleptidae subfam. n., is established to accommodate it. Undoubtedly, Metaleptus represents a very old and primitive form of nematode, the morphology of which indicates affinities also to physalopterids, cucullanids and acanthocheilids.     

The decrease in seed germination ofStriga hermonthica in Benin in the course of the rainy season is due to a dying-off process

Germination rate and viability ofStriga hermonthica seeds in the field in the Republic of Benin decreased steadily in the course of the rainy season. The percentage of germinating seeds decreased from 82% on April 13, 1993 to 16% on October 13, 1993. The percentage of viable seeds, according to the tetrazolium colour test, decreased in the same period from 90% to 15%. In the subsequent rainy season these values further decreased and it was concluded that the seeds do not enter a stage of secondary dormancy. This implies that if host plants (including wild hosts) are consistently kept away from infested fields for one or two year periods, this will lead to a dramatic decrease in the number of viableS. hermonthica seeds in the soil.     

Biogeography and phylogeny of Paraergasilus Markevich, 1937 (Copepoda: Ergasilidae) with descriptions of two new species from the gills of grey mullet

Two new species of Paraergasilus are reported from the gills of four species of grey mullet (Mugilidae). Paraergasilus dichotomus n. sp. was recorded on M. cephalus Linn. from New South Wales, Australia. Paraergasilus curtus n. sp. was found on the same host in Western Australia, on Valamugil cunnesius (Valenciennes) from the Philippines, on Valamugil seheli (Forsskal) from Sri Lanka and on Liza macrolepis (Smith) from Socotra, Yemen. Both new species differ from congeners in possessing a bifid antennary claw. The distribution of Paraergasilus species is summarized and the host specificity of Paraergasilus species is examined. Phylogenetic analysis of the relationships between Paraergasilus species indicated that there are two main lineages within the genus.     

野外大熊猫粪便中内寄生虫病的研究

自1985年11月至1988年12月.我们对四川省的27个县、市和8个自然保护区及甘肃省的文县和白水河自然保护区的不同海拔、不同地域的野外大熊猫粪便共计2680份.每份称取适量粪便,用沉淀法和漂浮法(漂浮液为硫酸镁饱和溶液)进行检查。检查结果,在1505份粪便内发现有西氏蛔虫(Ascaris schroederi)卵,感染率56.15%;在121份粪便内发现熊弓蛔虫(Toxas-caris seleactis)卵,阳性率4.51%;在13份粪便中发现槽盘吸虫(Ogmocotyle sp.)卵,感染率0.48%;在3份粪便中发现圆形线虫(Strongylata)卵,感染率0.11%,在1份粪便内发现肺线虫幼虫,阳性率0.04%。调查结果表明,西氏蛔虫是大熊猫体内寄生虫的优势种,而且不同地区,不同海拔高度和不同年龄的大熊猫感染情况无明显差别。因此,对大熊猫西氏蛔虫的进一步研究是保护大熊猫的一大课题。     

矢尖蚧蚜小蜂种群数量动态及其自然控制作用

矢尖蚧蚜小蜂(Aphytis yanonensis DeBach et Rosen)是矢尖蚧未产卵雌成虫的一种体外寄生蜂。主要以幼虫越冬。贵阳花溪地区7—8月和10—11月是该蜂发生的两个主要时期。寄生率叶片高于枝条、叶面高于叶背。全年的寄生率最高峰出现在11月、最低峰出现在6月。     

Parasitic copepods of Carcharhinidae and Sphyridae (Elasmobranchia) from the Atlantic Ocean

Seventy-four sharks of the families Carcharhinidae and Sphyridae, mainly from the central Atlantic Ocean, were examined. Fourteen species of Copepoda were found on them. Prionace glauca and Sphyrna zygaena are new hosts for the copepod Pandarus floridanus. Kroyeria carchariaeglauci is reported from the nasal cavities of Prionace glauca for the first time.     

硬序重寄生的生活习性

对中国云南一山地针阔叶混交林区的初步调查和观察表明：颤香料重寄生植物只有硬序重寄生一个种;该植物是全寄生性的专性重寄生植物,黄褐色,主要寄生于显脉松寄生上,生活在灌木层和乔木冠层之间以及稀疏林的茎干和大柱上。硬序重寄生为细小灌木,雌雄异株,植体在寄主体外部分1年生,但在寄生主体内部分可能多年生;有寄生位置移动现象,其花或果实着生密度较大,全年内都有花和果实成熟。种子传播媒介是鸟类,花粉传播媒介可能是蚂蚁,硬序重寄生的生活习性与生态金字塔等生物学规律,以及与以寄主和传播种子与花粉的鸟,虫的达应性密切相关。