Landscape context affects genetic diversity at a much larger spatial extent than population abundance.
Landscape context affects genetic diversity at a much larger spatial extent than population abundance.
复制标题
景观环境对遗传多样性的影响空间范围远大于人口丰度。
作者：
Nathan D. Jackson;L. Fahrig
区域景观环境影响当地人口的命运，但这种影响的空间范围（称为“影响规模”）很难预测。因此，保护管理的一个主要问题是了解控制影响规模的因素，以便在生物相关的空间尺度上测量和管理焦点区域周围的景观结构。一个未解决的问题是影响的规模是否以及如何取决于所测量的人群反应（例如，丰度与存在/不存在）。如果特定物种的种群结果的影响程度不同，基于一种结果的管理可能会损害另一种结果，从而使保护决策进一步复杂化。在这里，我们使用基于个体的模拟模型来研究栖息地数量和破碎程度不同的景观影响规模在三种种群反应（局部丰度、存在/不存在和遗传多样性）之间有何不同。我们还探讨了测量的人口响应如何影响栖息地数量和破碎化在塑造当地人口方面的相对重要性，以及分散距离如何调节这些影响的程度和空间规模。我们发现，对当地人口影响最大的空间尺度取决于测量结果，预计丰度较小，存在/不存在为中等，遗传多样性较大。空间尺度的增加可能是由于结果受到调节的时间尺度的增加造成的（当地遗传多样性在最大数量的世代中受到调节）。因此，多代的扩散和基因流动将当地人口模式与区域人口规模联系起来。栖息地数量的影响主导了破碎化对所有三个结果的影响。扩散距离的增加大大降低了丰度，但不会降低存在/不存在或遗传多样性。我们的结果表明，根据种群丰度数据在空间尺度上管理受保护物种可能会忽略对种群遗传多样性和持久性的更广泛的景观影响，这支持了管理保护关注区域周围大型缓冲区的重要性。
Regional landscape context influences the fate of local populations, yet the spatial extent of this influence (called the "scale of effect") is difficult to predict. Thus, a major problem for conservation management is to understand the factors governing the scale of effect such that landscape structure surrounding a focal area is measured and managed at the biologically relevant spatial scale. One unresolved question is whether and how scale of effect may depend on the population response measured (e.g., abundance vs. presence/absence). If scales of effect differ across population outcomes of a given species, management based on one outcome may compromise another, further complicating conservation decision making. Here we used an individual-based simulation model to investigate how scales of effect of landscapes that vary in the amount and fragmentation of habitat differ among three population responses (local abundance, presence/absence, and genetic diversity). We also explored how the population response measured affects the relative importance of habitat amount and fragmentation in shaping local populations, and how dispersal distance mediates the magnitude and spatial scale of these effects. We found that the spatial scale most strongly influencing local populations depended on the outcome measured and was predicted to be small for abundance, medium-sized for presence/absence, and large for genetic diversity. Increasing spatial scales likely resulted from increasing temporal scales over which outcomes were regulated (with local genetic diversity being regulated over the largest number of generations). Thus, multiple generations of dispersal and gene flow linked local population patterns to regional population size. The effects of habitat amount dominated the effects of fragmentation for all three outcomes. Increased dispersal distance strongly reduced abundance, but not presence/absence or genetic diversity. Our results suggest that managing protected species at spatial scales based on population abundance data may ignore broader landscape effects on population genetic diversity and persistence, lending support to the importance of managing large buffers surrounding areas of conservation concern.