Study on diversity of fish communities in Lake Tangenyika

在过去的十年中，我们的实地研究表明，合作种间关系以及竞争的高度纳入坦噶尼喀湖沿海鱼类群落。本项目在赞比亚的咸水区和布隆迪的北方水域进行了实地调查，主要研究内容包括：（1）赞比亚海岸线沿着不同地点鱼类群落的比较;（2）鱼类的生境利用、繁殖行为、交配系统，（3）慈鲷科鱼类分类学的再研究。主要结果如下：（1）岩栖动物在形态和颜色上的地理差异大于砂栖动物 ...更多信息 （B）从远古时代（至少从3万年前）就存在的两个长沙滩（7和13 km）对遗传流起着屏障作用;（c）鱼类群落中一些相当的摄食生态位，特别是底栖动物的摄食生态位，被相关但不同的物种占据，并且在一些底栖动物中发现了特征位移。此外，还使用刺网探索了深海底（60-160米深）的鱼类群落。它们完全由肉食性鱼类组成，如食动物、底栖动物、食鱼动物和食鳞动物。最突出的是兼性壳亲鱼的表型可塑性。在使用空腹足类壳作为产卵基质的种群中，只有雌性或雄性和雌性都比使用岩石洞和裂缝的种群矮小。美鳍亮丽鲷（Lepidiolamprologus callipterus）和细鳞亮丽鲷（Lepidiolamprologus attenuatus）的部分抱壳种群在动物界中表现出了最大的两性异形（雄性>>雌性）。对一些群体的分类学审查（即，奇非鲫属）的研究工作将于近期完成。此外，建立慈鲷科鱼类遗传树的DNA分析正在进行中。少

Our field studies in the last decade have revealed that cooperative interspecific relationships as well as competitivc ones are highly incorporated in coastal fish communities in Lake Tanganyika. The great diversity of the fish communities are attributed to the explosive radiation of cichlids descended from several old lineages.In this project, we carried out the field studies at the sourthern water in Zambia and at the northern water in Burundi and mainly concerned with (1) comparison of fish communities in separated localities along the Zambian shoreline, (2) habitat utilization, reproductive behavior, mating systems, feeding bchaviour, and inter- and intraspecific interactions in cichlid fishes, and (3) taxonomic re-examination of cichlid fishes.For the first subject, we conducted line censuses at more than 10 localities and collected specimens. Main results we obtained were as follows : (a) geographic variations in morphology and coloration were greater in rock-dwellers than sand-d … More wellers, (b) it was suggested that two long sand beaches (7 and 13 km long) which have existed from ancient times (at least from 30 thousand years ago) functioned as barriers against genetic flow, and (c) some equivalent feeding niches, especially those of benthos-feeders, in fish communities were occupied by related but different species, and charcter displacement was found in some benthos-feeders. Furthermore, fish communities on the deep bottom (60-160 m deep) were explored by using gillnets. They consisted exclusively of carnivorous fishes such as zooplankton-feeders, benthos-feeders, piscivores and scaleeaters.On the second subject, we obtained many results. The most outstanding was the phenotypic plasticity in facultative shell-brooders. In populations that use empty gastropod shells as spawning substrate, only females or both males and females dwarfed compared with populations that use rock holes and crevices. Some shell-brooding populations of Lamprologus callipterus and Lepidiolamprologus attenuatus exhibited nearly the greatest sexual size dimorphism (male>>female)in the animal kingdom.For the third subject, specimens we collected in Burundi and Zambia waters were examined and compared with type specimens deposited in the British Museum etc.. Taxonomic reviews on some groups (i.c., the genus Xenotilapia) will be completed in near future. And, DNA analyzes for establishing a phylogenic tree of cichlid fishes are in progress. Less