Samia Yasmine, Lutscher Frithjof, Hastings Alan
Department of Mathematics and Statistics, University of Ottawa, Ottawa, Canada.
Department of Mathematics and Statistics, University of Ottawa, Ottawa, Canada Department of Biology, University of Ottawa, Ottawa, Canada
J R Soc Interface. 2015 Sep 6;12(110):0435. doi: 10.1098/rsif.2015.0435.
The movement of fish in watersheds is frequently inhibited by human-made migration barriers such as dams or culverts. The resulting lack of connectivity of spatial subpopulations is often cited as a cause for observed population decline. We formulate a matrix model for a spatially distributed fish population in a watershed, and we investigate how location and other characteristics of a single movement barrier impact the asymptotic growth rate of the population. We find that while population growth rate often decreases with the introduction of a movement obstacle, it may also increase due to a 'retention effect'. Furthermore, obstacle mortality greatly affects population growth rate. In practice, different connectivity indices are used to predict population effects of migration barriers, but the relation of these indices to population growth rates in demographic models is often unclear. When comparing our results with the dentritic connectivity index, we see that the index captures neither the retention effect nor the influences of obstacle mortality. We argue that structural indices cannot entirely replace more detailed demographic models to understand questions of persistence and extinction. We advocate the development of novel functional indices and characteristics.
流域中鱼类的洄游常常受到诸如大坝或涵洞等人为迁移障碍的抑制。由此导致的空间亚种群连通性的缺乏，常被认为是观察到的种群数量下降的一个原因。我们为流域内空间分布的鱼类种群建立了一个矩阵模型，并研究单个迁移障碍的位置和其他特征如何影响种群的渐近增长率。我们发现，虽然引入迁移障碍时种群增长率通常会下降，但由于“滞留效应”，其也可能会增加。此外，障碍死亡率对种群增长率有很大影响。在实际应用中，不同的连通性指数被用于预测迁移障碍对种群的影响，但这些指数与人口统计学模型中种群增长率的关系往往并不明确。当将我们的结果与树枝状连通性指数进行比较时，我们发现该指数既没有捕捉到滞留效应，也没有捕捉到障碍死亡率的影响。我们认为，结构指数不能完全取代更详细的人口统计学模型来理解种群的存续和灭绝问题。我们主张开发新的功能指数和特征。
