Haugen Thrond O, Winfield Ian J, Vøllestad L Asbjørn, Fletcher Janice M, James J Ben, Stenseth Nils Chr
Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway.
Proc Biol Sci. 2006 Dec 7;273(1604):2917-24. doi: 10.1098/rspb.2006.3659.
The ideal free distribution (IFD) theory is one of the most influential theories in evolutionary ecology. It predicts how animals ought to distribute themselves within a heterogeneous habitat in order to maximize lifetime fitness. We test the population level consequence of the IFD theory using 40-year worth data on pike (Esox lucius) living in a natural lake divided into two basins. We do so by employing empirically derived density-dependent survival, dispersal and fecundity functions in the estimation of basin-specific density-dependent fitness surfaces. The intersection of the fitness surfaces for the two basins is used for deriving expected spatial distributions of pike. Comparing the derived expected spatial distributions with 50 years data of the actual spatial distribution demonstrated that pike is ideal free distributed within the lake. In general, there was a net migration from the less productive north basin to the more productive south basin. However, a pike density-manipulation experiment imposing shifting pike density gradients between the two basins managed to switch the net migration direction and hence clearly demonstrated that the Windermere pike choose their habitat in an ideal free manner. Demonstration of ideal free habitat selection on an operational field scale like this has never been undertaken before.
理想自由分布（IFD）理论是进化生态学中最具影响力的理论之一。它预测了动物应该如何在异质栖息地中分布，以实现终身适应度的最大化。我们利用生活在一个被分为两个流域的天然湖泊中的梭子鱼（白斑狗鱼）长达40年的数据，来检验IFD理论在种群水平上的影响。我们通过在估计特定流域的密度依赖适应度曲面时采用根据经验得出的密度依赖生存、扩散和繁殖力函数来做到这一点。两个流域适应度曲面的交点用于推导梭子鱼的预期空间分布。将推导得出的预期空间分布与50年的实际空间分布数据进行比较，结果表明梭子鱼在湖泊中呈理想自由分布。一般来说，存在从生产力较低的北部流域向生产力较高的南部流域的净迁移。然而，一项在两个流域之间施加变化的梭子鱼密度梯度的梭子鱼密度操纵实验成功地改变了净迁移方向，从而清楚地表明温德米尔湖的梭子鱼以理想自由的方式选择它们的栖息地。像这样在实际操作的野外尺度上证明理想自由的栖息地选择此前从未有过。
