Fishes from the Edge of Victoria Falls, Africa: Demise of a Physical Barrier for Downstream Invasions
Fishes from the Edge of Victoria Falls, Africa: Demise of a Physical Barrier for Downstream Invasions
复制标题
非洲维多利亚瀑布边缘的鱼类：下游入侵的物理屏障的消失
作者：
E. Balon
从维多利亚瀑布（赞比亚-罗得西亚）边缘采集的鱼类样本被用来解释两个鱼类动物群之间的交流历史和卡里巴湖的入侵。前赞比西河上游的鱼类与前中赞比西河和赞比西河下游的鱼类有着不同的起源。当两个独立的河流系统，现在组成赞比西河合并作为一个结果，构造隆起，统一点成为维多利亚瀑布。湍急的沃茨在玄武岩熔岩的断层线上沿着切割出陡峭的峡谷。该福尔斯被认为是一个物理屏障分隔鱼类的上游和中部赞比西河。最近的环境变化，伴随着人造湖卡里巴的创建，以及上游赞比西鱼入侵湖泊，证明了福尔斯作为下游屏障的无效性。本文提出了一种由生境差异和生态位数量差异引起的生态屏障理论。当这两条分开的河流第一次汇合时，这道生态屏障已经运作了50万年。
Samples of fishes from the edge of Victoria Falls (Zambia-Rhodesia) were utilized in explaining the history of exchanges between two fish faunas and the invasion of Lake Kariba. Fishes of the pre-Upper Zambezi River are of a different origin from those in the pre-Middle and Lower Zambezi. When the two separate river systems which now make up the Zambezi were united as a result of a tectonic upwarp, the point of unification became the Victoria Falls. The rushing waters of the river cut steep gorges along the fault lines in the basalt lava. The Falls were considered a physical barrier separating fishes of the Upper and Middle Zambezi. Recent environmental changes which accompanied the creation of man-made Lake Kariba, together with the invasion of the lake by Upper Zambezi fishes, demonstrate the ineffectiveness of the Falls as a downstream barrier. A theory of an ecological barrier caused by differences in habitat and by differences in number of available niches is presented here. This ecological barrier was functional for 500,000 years, when the separate rivers first united.