The time to extinction of a colonizing propagule of lizards increases with island area
The time to extinction of a colonizing propagule of lizards increases with island area
复制标题
蜥蜴繁殖体灭绝的时间随着岛屿面积的增加而增加
作者：
T. Schoener;A. Schoener
物种灭绝的原因和如何防止物种灭绝的问题是基础生态学和应用生态学的一个关键问题。三种岛屿生物地理实地研究对这一问题作出了特别重要的贡献。首先，各种鸟类研究表明，在小种群中，灭绝时间与种群规模呈负相关；较小的岛屿通常人口较少（见参考文献1和H. L.琼斯、J. M.戴蒙德和M.吉尔平，正在准备手稿）。其次，在一项关于节肢动物的研究中，通过实验减少已经饱和的红树林岛屿的面积，导致物种数量减少，可能是因为种群规模减少。第三，在一项对哺乳动物的研究中，将小型的、大小不一的种群（繁殖体）实验性地引入岛屿，较大的繁殖体存活的时间更长。在蜥蜴的研究中，实验改变了岛屿面积和繁殖体大小，试图分离它们的影响。结果表明：(1)同一物种的灭绝时间随岛屿面积的增加呈单调增长趋势；(2)在某一岛屿区域以上，迅速发生了殖民；低于这个阈值，繁殖体很快就灭绝了；(3)繁殖体大小不受影响。
The question of what causes species extinction and how to prevent it is a crucial one for both basic and applied ecology. Three kinds of island-biogeographical field studies have made particularly important contributions towards this problem. First, a variety of bird studies suggest for small populations a negative relation between extinction time and population size; smaller islands typically have smaller populations (see ref. 1 and H. L. Jones, J. M. Diamond and M. Gilpin, manuscript in preparation). Second, in a study on arthropods2, experimentally reducing the area of already saturated mangrove islands caused numbers of species to decrease, presumably because of reduced population sizes. Third, in a study of mammals3 in which small, variably sized populations of colonists (propagules) were experimentally introduced onto islands, larger propagules survived longer. In the present study with lizards, both island area and propagule size were varied experimentally in an attempt to separate their effects. The results show: (1) for a given species, time to extinction increased with island area in a monotonic fashion; (2) above a certain island area, rapid colonization occurred; below that threshold, propagules went extinct quickly; and (3) propagule size had no effect.