den Boer P J
Biological Station LUW, Kampsweg, 27 9418 PD, Wijster, The Netherlands.
Oecologia. 1991 May;86(4):484-491. doi: 10.1007/BF00318314.
It is often claimed that the fluctuation of numbers in field populations is fundamentally different from random walks of densities, in that population size is kept between certain positive limits. To test this hypothesis patterns of fluctuation in field populations were compared with random walks of density of about the same duration. It was found that the boundaries (Log-Range) between which numbers fluctuate in field populations increase with time to about the same extent as in comparable random walks of density. Moreover, deviations of the trend of numbers over years (Average lnR) from zero trend in populations of 62 (carabid) species were just those expected for simulated random walk runs, with the median value of Var(lnR), and different values for mean population size that cover the possible range of "survival times" for these species. This means that the null hypothesis that in the field numbers would fluctuate as random walks of densities could not be rejected. Although it is not very probable that field populations fluctuate exactly like random walks of densities, random walk models appear to mimic the fluctuation patterns of field populations sufficiently closely to explain what happens in nature, and to deny the need for regulation. The same conclusion was drawn in earlier studies where statistical tests were applied to fluctuation patterns of field populations (Den Boer and Reddingius 1989; Den Boer 1990a). Random walks of densities do not exclude the possibility that local populations can persist for some centuries.
人们常常声称，野外种群数量的波动与密度的随机游走有着根本的不同，因为种群数量被维持在一定的正极限之间。为了检验这一假设，将野外种群的波动模式与持续时间大致相同的密度随机游走进行了比较。结果发现，野外种群数量波动的边界（对数范围）随时间的增加幅度与密度可比的随机游走大致相同。此外，62种（步甲科）物种的种群数量多年趋势（平均lnR）与零趋势的偏差，正是模拟随机游走运行所预期的，其Var(lnR)的中位数，以及平均种群大小的不同值涵盖了这些物种“生存时间”的可能范围。这意味着，野外数量会像密度随机游走一样波动的零假设无法被拒绝。虽然野外种群数量的波动不太可能与密度随机游走完全一样，但随机游走模型似乎能够充分紧密地模拟野外种群的波动模式，从而解释自然界中发生的情况，并否定了调控的必要性。在早期将统计检验应用于野外种群波动模式的研究中也得出了相同的结论（登·布尔和雷丁纽斯，1989年；登·布尔，1990a）。密度随机游走并不排除当地种群能够持续存在几个世纪的可能性。
