Redpath Stephen M, Mougeot François, Leckie Fiona M, Elston David A, Hudson Peter J
Ecol Lett. 2006 Apr;9(4):410-8. doi: 10.1111/j.1461-0248.2006.00895.x.
The role of parasites in regulating populations has been the subject of debate. We tested whether parasites caused population cycles in red grouse by manipulating parasite intensities in four, paired 1 km(2) study areas during cyclic population declines over 4 years. Parasite reductions led to (1) larger grouse broods, (2) higher population densities in both autumn and spring, (3) reduced autumn population declines in one of two regions, and (4) reduced spring declines, but only in the first year. We infer that a single trophic interaction between a parasite and its host does not explain cyclic dynamics in spring breeding density in this species, although it contributed to the start of a cyclic decline. Another process was operating to drive the populations down. Together with our other results these findings emphasize that both trophic and intrinsic processes may act within populations to cause unstable dynamics.
寄生虫在调节种群数量方面的作用一直是争论的焦点。我们通过在4年的周期性种群数量下降期间，对4对1平方公里的研究区域内的寄生虫感染强度进行控制，来测试寄生虫是否导致了红松鸡种群数量的周期性变化。寄生虫数量的减少导致了：（1）松鸡育雏数量增加；（2）秋季和春季的种群密度都更高；（3）在两个区域中的一个区域，秋季种群数量下降幅度减小；（4）春季种群数量下降幅度减小，但仅在第一年。我们推断，尽管寄生虫与其宿主之间的单一营养相互作用促成了周期性下降的开始，但它并不能解释该物种春季繁殖密度的周期性动态变化。另一个过程在促使种群数量下降。连同我们的其他研究结果，这些发现强调，营养过程和内在过程都可能在种群内部起作用，从而导致不稳定的动态变化。
