The marginal value theorem (MVT) provides a framework to predict how habitat modifications related to the distribution of resourcesover patches should impact the realized fitness of individuals and their optimal rate of movement (or patch residence times) across the habitat. The MVT theory has focused on the consequences of changing the shape of the gain functions in some patches, describing for instance, patch enrichment. However, an alternative form of habitat modification is habitat conversion, whereby patches are converted from one existing type to another (e.g., closed habitat to open habitat). In such a case, the set of gain functions existing in the habitat does not change, only their relative frequencies does. This case however has received comparatively little attention. Here we analyze mathematically the consequences of habitat conversion under the MVT. We study how realized fitness and the average rate of movement should respond to changes in the frequency distribution of patch-types and how they should covary. We further compare the response of optimal and non-plastic foragers. We find that the initial pattern of patch exploitation in a habitat, characterized by the regression slope of patch yields over residence times, can help predict the qualitative responses of fitness and movement rate following habitat conversion. We also find that for some habitat conversion patterns, optimal and non-plastic foragers exhibit qualitatively different responses, and that adaptive foragers can have opposite responses in the short- and long-term following habitat conversion. We suggest taking into account behavioral responses may help better understand the ecological consequences of habitat conversion.

中文翻译：

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最佳觅食者应如何应对生境变化：生境转变的后果

边际价值定理（MVT）提供了一个框架，用于预测与斑块上的资源分布有关的栖息地修改将如何影响个体的实际适应度及其在整个栖息地中的最佳移动速率（或斑块停留时间）。MVT理论集中在改变某些补丁中增益函数的形状的后果上，例如描述了补丁的丰富化。但是，栖息地改造的另一种形式是栖息地转换，即将斑块从一种现有类型转换为另一种（例如，从封闭的栖息地转变为开放的栖息地）。在这种情况下，栖息地中存在的一组增益函数不会改变，只有它们的相对频率会改变。但是，这种情况很少受到关注。在这里，我们在数学上分析了MVT下栖息地转换的后果。我们研究了实现的适应度和平均运动速率应如何响应贴片类型的频率分布变化以及它们应该如何变曲。我们进一步比较了最佳和非塑性觅食者的反应。我们发现，栖息地斑块开发的初始模式以斑块产量随停留时间的回归斜率表征，可以帮助预测栖息地转换后适应度和运动速率的定性响应。我们还发现，对于某些生境转换模式，最佳和非塑性觅食者表现出质的不同响应，而适应性觅食者在生境转换后的短期和长期中可能具有相反的响应。