Why trees migrate so fast: Confronting theory with dispersal biology and the paleorecord
Why trees migrate so fast: Confronting theory with dispersal biology and the paleorecord
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DOI：
10.1086/286162
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发表时间：
1998-08-01
影响因子：
2.9
通讯作者：
Clark, JS
中科院分区：
文献类型：
--
作者：
Clark, JS
里德悖论描述了这样一个事实，即经典模型不能解释更新世末期树木的快速（10（2）-10（3）m yr（-1））蔓延。我用现场估计种子传播的integrodifference方程和人口增长的模拟模型表明，扩散数据是兼容的快速传播。扩散的估计排除了通过扩散而迅速传播的可能性。积分差分模型预测，如果种子阴影有一个长的“胖”尾巴，那么快速传播是可能的，尽管平均传播距离很短。它进一步预测，速度是更敏感的生活史比经典的扩散。由于种子阴影的尾部不能与数据拟合，这种模型的应用受到挫折。然而，这些数据可以用来测试一个“长距离”的假设对替代（“本地”）模型的扩散使用赤池的信息标准和似然比测试。试验表明，数据与>10%的种子分散为长（10（2）m）厚尾籽粒一致。基于这种内核的模型预测传播速度与从花粉记录中推断的传播速度一样快。如果厚尾扩散解释了这些快速的速度，那么令人惊讶的是，在具有不同生活史的类群之间，没有看到速度的巨大差异。快速传播的推断，加上缺乏明显的生命史效应，表明速度可能还没有达到其潜力，被气候变化率，地理，或两者兼而有之。
Reid's paradox describes the fact that classical models cannot account for the rapid (10(2)-10(3) m yr(-1)) spread of trees at the end of the Pleistocene. I use field estimates of seed dispersal with an integrodifference equation and simulation models of population growth to show that dispersal data are compatible with rapid spread. Dispersal estimates lay to rest the possibility that rapid spread occurred by diffusion. The integrodifference model predicts that, if the seed shadow has a long "fat" tail, then rapid spread is possible, despite short average dispersal distances. It further predicts that velocity is more sensitive to life history than is classical diffusion. Application of such models is frustrated because the tail of the seed shadow cannot be fitted to data. However, the data can be used to test a "long-distance" hypothesis against alternative ("local") models of dispersal using Akaike's Information Criterion and likelihood ratio tests. Tests show that data are consistent with >10% of seed dispersed as a long (10(2) m) fat-tailed kernel. Models based on such kernels predict spread as rapid as that inferred from the pollen record. If fat-tailed dispersal explains these rapid rates, then it is surprising not to see large differences in velocities among taxa with contrasting life histories. The inference of rapid spread, together with lack of obvious life-history effects, suggests velocities may have not reached their potentials, being stalled by rates of climate change, geography, or both.