Gautestad Arild O, Mysterud Ivar
Department of Biology, University of Oslo, Norway.
Am Nat. 2005 Jan;165(1):44-55. doi: 10.1086/426673. Epub 2004 Nov 22.
Ecological theory related to animal distribution and abundance is at present incomplete and to some extent naive. We suggest that this may partly be due to a long tradition in the field of model development for choosing mathematical and statistical tools for convenience rather than applicability. Real population dynamics are influenced by nonlinear interactions, nonequilibrium conditions, and scaling complexity from system openness. Thus, a coherent theory for individual-, population-, and community-level processes should rest on mathematical and statistical methods that explicitly confront these issues in a manner that satisfies principles from statistical mechanics for complex systems. Instead, ecological theory is traditionally based on premises from simpler statistical mechanical theory for memory-free, scale-specific, random-walk, and diffusion processes, while animals from many taxa generally express strategic homing, site fidelity, and conspecific attraction in direct violation of primary model assumptions. Thus, the main challenge is to generalize the theory for memory-free physical, many-body systems to include a more realistic memory-influenced framework that better satisfies ecological realism. We describe, simulate, and discuss three testable aspects of a model for multiscaled habitat use at the individual level: (1) scale-free distribution of movement steps under influence of self-reinforcing site fidelity, (2) fractal spatial dispersion of intra-home range relocations, and (3) nonasymptotic expansion of observed intra-home range patch use with increasing set of relocations. Examples of literature data apparently supporting the conjecture that multiscaled, strategic space use is widespread among many animal taxa are also described. We suggest that the present approach, which provides a protocol to test for influence from scale-free, memory-dependent habitat use at the individual level, may also point toward a guideline for development of a generalized theoretical framework for complex population kinetics and spatiotemporal population dynamics.
目前，与动物分布和丰度相关的生态理论并不完整，在某种程度上还很幼稚。我们认为，这可能部分是由于模型开发领域长期以来的传统，即选择数学和统计工具时更多地是出于便利性而非适用性。实际的种群动态受到非线性相互作用、非平衡条件以及系统开放性导致的尺度复杂性的影响。因此，一个关于个体、种群和群落水平过程的连贯理论应该基于数学和统计方法，这些方法应以符合复杂系统统计力学原理的方式明确应对这些问题。相反，生态理论传统上基于更简单的统计力学理论的前提，适用于无记忆、特定尺度、随机游走和扩散过程，而许多分类群的动物通常表现出策略性归巢、位点忠实性和种内吸引，这直接违背了主要的模型假设。因此，主要挑战在于将无记忆物理多体系统的理论推广到一个更现实的、受记忆影响的框架，该框架能更好地符合生态现实。我们描述、模拟并讨论了一个关于个体水平多尺度栖息地利用模型的三个可检验方面：（1）在自我强化的位点忠实性影响下运动步长的无标度分布；（2）家域内重新定位的分形空间扩散；（3）随着重新定位次数增加，观察到的家域内斑块利用的非渐近扩展。还描述了一些文献数据实例，这些数据显然支持了多尺度、策略性空间利用在许多动物分类群中广泛存在的推测。我们认为，目前的方法提供了一个在个体水平测试无标度、依赖记忆的栖息地利用影响的方案，也可能为复杂种群动力学和时空种群动态的广义理论框架发展指明方向。
