Amarasekare Priyanga
Department of Biological Sciences, Purdue University, 47907, West Lafayette, IN, USA.
Oecologia. 1994 Nov;100(1-2):166-176. doi: 10.1007/BF00317143.
I attempted to characterize spatial units of local dynamics and dispersal in banner-tailed kangaroo rats (Dipodomys spectabilis), to determine if spatial structure influenced population dynamics in the way predicted by current metapopulation models. D. spectabilis exhibited a hierarchical spatial structure. "Local populations" that appeared as discrete entities on a scale of kilometers were subdivided into clusters of mounds on a scale of meters. This structure, however, cannot be characyerized in terms of the discrete habitat patches envisioned by the metapopulation models. Occupied areas were statistically distinguishable from the surrounding matrix, but this difference was only quantitative. There were no discrete boundaries between occupied areas and the matrix. Habitat within occupied areas was heterogeneous, and occupied areas in different locations were statistically distinguishable from each other. High heterogeneity within occupied areas, and high contrast among them, make it difficult to define what is a suitable habitat patch for D. spectabilis. On a smaller spatial scale, there was significant aggregation of resident mounds within occupied areas. These aggregations, however, do not correspond to discrete habitat patches. Rather, they appear to result from an interaction between fine-scale habitat heterogeneity and limited dispersal due to natal philopatry and low adult vagility. These complications make it difficult to identify habitat patches independent of the species' distribution. For species like D. spectabilis that are patchily distributed but do not occupy discrete habitat patches, a patch occupancy approach does not seem appropriate for describing spatial structure. Hierarchical spatial structure underscores the need for a framework that incorporates multiple scales of spatial structure, rather than one that pre-imposes a single spatial scale as being important for population dynamics. A framework that (i) considers patchiness as a combination of both habitat heterogeneity, and life-history and behavioral characteristics, and (ii) incorporates hierarchical spatial structure, appears to be the most suitable for conceptualizing spatial dynamics of behaviorally complex vertebrates such as D. spectabilis.
我试图描述旗尾更格卢鼠（Dipodomys spectabilis）局部动态和扩散的空间单元，以确定空间结构是否以当前集合种群模型所预测的方式影响种群动态。旗尾更格卢鼠呈现出一种层次化的空间结构。在千米尺度上看似离散实体的“局部种群”，在米尺度上又被细分为土丘集群。然而，这种结构无法按照集合种群模型所设想的离散栖息地斑块来进行描述。被占据区域在统计学上与周围基质可区分，但这种差异只是数量上的。被占据区域与基质之间没有离散的边界。被占据区域内的栖息地是异质的，不同位置的被占据区域在统计学上也相互可区分。被占据区域内的高度异质性以及它们之间的高对比度，使得很难界定什么是适合旗尾更格卢鼠的栖息地斑块。在较小的空间尺度上，被占据区域内有显著的常驻土丘聚集。然而，这些聚集并不对应于离散的栖息地斑块。相反，它们似乎是由精细尺度的栖息地异质性与由于出生地偏爱和成年个体低迁移性导致的有限扩散之间的相互作用所产生的。这些复杂情况使得难以独立于物种分布来识别栖息地斑块。对于像旗尾更格卢鼠这样分布零散但不占据离散栖息地斑块的物种，斑块占据方法似乎不适用于描述空间结构。层次化的空间结构强调需要一个纳入多种空间结构尺度的框架，而不是预先设定单一空间尺度对种群动态很重要的框架。一个（i）将斑块性视为栖息地异质性以及生活史和行为特征的组合，并且（ii）纳入层次化空间结构的框架，似乎最适合概念化像旗尾更格卢鼠这样行为复杂的脊椎动物的空间动态。
