Namba T, Umemoto A, Minami E
Department of Natural Science, Osaka Women's University, Daisen-cho 2-1, Sakai, Osaka, 590-0035, Japan.
Theor Popul Biol. 1999 Aug;56(1):123-37. doi: 10.1006/tpbi.1999.1422.
We consider systems with one predator and one prey, or a common predator and two prey species (apparent competitors) in source and sink habitats. In both models, the predator species is vulnerable to extinction, if productivity in the source is insufficient to rescue demographically deficient sink populations. Conversely, in the model with two prey species, if the source is too rich, one of the prey species may be driven extinct by apparent competition, since the predator can maintain a large population because of the alternative prey. Increasing the rate of predator movement from the source population has opposite effects on prey and predator persistence. High emigration rate exposes the predator population to danger of extinction, reducing the number of individuals that breed and produce offspring in the source habitat. This may promote coexistence of prey by relaxing predation pressure and apparent competition between the two prey species. The number of sinks and spatial arrangement of patches, or connectivity between patches, also influence persistence of the species. More sinks favor the prey and fewer sinks are advantageous to the predator. A linear pattern with the source at one end is profitable for the predator, and a centrifugal pattern in which the source is surrounded by sinks is advantageous to the prey. When the dispersal rate is low, effects of the spatial structure may exceed those of the number of sinks. In brief, productivity in patches and patterns of connectivity between patches differentially influence persistence of populations in different trophic levels.
我们考虑在源生境和汇生境中具有一种捕食者和一种猎物，或一种常见捕食者和两种猎物物种（表观竞争）的系统。在这两种模型中，如果源生境中的生产力不足以拯救在数量上不足的汇种群，捕食者物种就容易灭绝。相反，在具有两种猎物物种的模型中，如果源生境过于丰富，其中一种猎物物种可能会因表观竞争而灭绝，因为捕食者可以因有替代猎物而维持大量种群。提高捕食者从源种群的迁移率对猎物和捕食者的持久性有相反的影响。高迁移率使捕食者种群面临灭绝的危险，减少了在源生境中繁殖和产生后代的个体数量。这可能通过减轻捕食压力和两种猎物物种之间的表观竞争来促进猎物的共存。汇的数量和斑块的空间排列，或斑块之间的连通性，也会影响物种的持久性。更多的汇有利于猎物，而较少的汇对捕食者有利。源在一端的线性格局对捕食者有利，而源被汇包围的离心格局对猎物有利。当扩散率较低时，空间结构的影响可能超过汇数量的影响。简而言之，斑块中的生产力和斑块之间的连通性模式对不同营养级种群的持久性有不同的影响。
