Sale P F, Tolimieri N
Great Lakes Institute for Environmental Research and Biological Sciences Department, University of Windsor, Windsor, Ontario, N9B 3P4, Canada e-mail:
Oecologia. 2000 Aug;124(2):166-171. doi: 10.1007/s004420050003.
There appears to be widespread acceptance that for a population to persist, some demographic parameter must be density dependent at some place or time. In this paper, we question the veracity and heuristic value of treating this statement as a general principle of ecology. We also point out that some processes that have recently been defined as density dependent are, in fact, not. Taken in its original sense, density dependence implies a change in demographic rates based on biological (generally negative) feedback. Situations exist, however, in which demographic rates change in relation to density without negative biological feedback. For example, per capita recruitment in marine populations will decrease as local population size increases even as absolute numbers of arriving larvae do not change. The failure to separate these density-related processes from true density-dependent processes affects our understanding of population regulation and of the way in which the natural world functions. Furthermore, focusing solely on density-dependent processes and their role in population regulation neglects to address numerous density-independent processes like disturbance and climatic variation that may have important impacts in determining population size.
人们似乎普遍认为，对于一个种群的持续存在而言，某些人口统计学参数在某些地点或时间必须是密度依赖的。在本文中，我们质疑将这一陈述视为生态学一般原则的真实性和启发价值。我们还指出，一些最近被定义为密度依赖的过程实际上并非如此。从其原始意义上讲，密度依赖意味着基于生物（通常为负）反馈的人口统计学速率的变化。然而，存在这样的情况，即人口统计学速率与密度相关，但没有负生物反馈。例如，即使到达幼虫的绝对数量不变，随着当地种群规模的增加，海洋种群的人均补充量也会下降。未能将这些与密度相关的过程与真正的密度依赖过程区分开来，会影响我们对种群调节以及自然世界运作方式的理解。此外，仅关注密度依赖过程及其在种群调节中的作用，忽略了许多与密度无关的过程，如干扰和气候变化，而这些过程在决定种群规模方面可能具有重要影响。
