Mechanistic modelling of animal dispersal offers new insights into range expansion dynamics across fragmented landscapes
Mechanistic modelling of animal dispersal offers new insights into range expansion dynamics across fragmented landscapes
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DOI：
10.1111/ecog.01041
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发表时间：
2014-12-01
期刊：
影响因子：
5.9
通讯作者：
Travis, Justin M. J.
中科院分区：
文献类型：
--
作者：
Bocedi, Greta;Zurell, Damaris;Travis, Justin M. J.
了解和预测的动态范围扩展是一个主要的主题，在生态学的入侵物种扩展到非本地地区的范围和物种改变其自然分布的气候变化的结果。在一个日益变化的景观中，一个关键问题是“种群如何在斑块景观中传播？”“扩散是分布区扩张的一个中心过程，虽然关于扩散核的形状如何影响扩散速度有相当多的理论，但我们对移民，运动和定居规则以及入侵率之间的关系知之甚少。在这里，我们使用一个简单的，单一物种的个人为基础的模型，明确模拟动物扩散，建立密度依赖的移民和定居规则如何与景观特征相互作用，以确定传播率。我们表明，取决于扩散行为和矩阵中的死亡率的风险，增加补丁的数量不一定最大化的传播率。这是由于两个影响：第一，个人分散在不断扩大的前线可能会表现出较低的净位移，因为他们通常不会旅行很远，然后才找到一个补丁;第二，随着高质量的栖息地，移民和定居的密度依赖性增加，可以减少移民的数量和净位移。传播速度最终取决于净传播距离、传播死亡率和传播个体数量之间的平衡，而这又取决于景观和物种传播行为之间的相互作用。这些结果突出表明，在异质景观的传播率预测是一项复杂的任务，需要更好地了解个人在移民，转移和定居决策中使用的规则。
Understanding and predicting the dynamics of range expansion is a major topic in ecology both for invasive species extending their ranges into non-native regions and for species shifting their natural distributions as a consequence of climate change. In an increasingly modified landscape, a key question is 'how do populations spread across patchy landscapes?' Dispersal is a central process in range expansion and while there is a considerable theory on how the shape of a dispersal kernel influences the rate of spread, we know much less about the relationships between emigration, movement and settlement rules, and invasion rates. Here, we use a simple, single species individual-based model that explicitly simulates animal dispersal to establish how density-dependent emigration and settlement rules interact with landscape characteristics to determine spread rates. We show that depending on the dispersal behaviour and on the risk of mortality in the matrix, increasing the number of patches does not necessarily maximise the spread rate. This is due to two effects: first, individuals dispersing at the expanding front are likely to exhibit lower net-displacement as they typically do not travel far before finding a patch; secondly, with increasing availability of high quality habitat, density-dependence in emigration and settlement can decrease the number of emigrants and their net-displacement. The rate of spread is ultimately determined by the balance between net travelled distance, the dispersal mortality and the number of dispersing individuals, which in turn depend on the interaction between the landscape and the species' dispersal behaviour. These results highlight that predicting spread rates in heterogeneous landscapes is a complex task and requires better understanding of the rules that individuals use in emigration, transfer and settlement decisions.