Airborne dispersal is a key part of the life history of many saprotrophic fungi. Theory suggests a transition from growth and resource capture to airborne dispersal at some point as the resource availability in a patch declines, but in the absence of an experimental model system this theory has not been empirically tested. For saprobes, resources are arrayed in an ever‐shifting archipelago of islands with the quality of each island being defined by patch size and resource density. We tracked how Phacidium lacerum, a saprotrophic fungus, allocated resources to dispersal in small and large islands of varying resource density through production of fruiting bodies. We found that Phacidium altered the timing and rate of dispersal allocation in response to both patch size and resource density. On small resource islands, Phacidium drastically increased dispersal allocation after reaching the edge of the patch; if resource density was sufficient, on larger resource islands, Phacidium began allocation to dispersal prior to reaching the edge of the island, suggesting an additional absolute total resource level cue. These results are consistent with a two‐cue model for the switch to allocation to airborne dispersal: 1) absolute resource level controlled by the fungus, 2) the fungus’ perception of patch size. This can be thought of as a mix between a full resource allocation switch (bang–bang) if the fungus perceives the patch is fully occupied with a smaller magnitude early shift (bet‐hedging) if absolute resource level crosses a threshold.

中文翻译：

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在模拟岛屿中散布在丝状真菌中的环境提示

空气传播是许多腐生真菌生活史的关键部分。理论表明，随着斑块中资源的可用性下降，在某个时候从增长和资源捕获到空中传播的过渡，但是在缺乏实验模型系统的情况下，该理论尚未经过经验检验。对于腐生菌，资源分布在不断变化的岛屿群岛中，每个岛屿的质量由斑块大小和资源密度定义。我们跟踪了腐生性真菌Phacidiumlacrum如何通过子实体的生产来分配资源以分散在资源密度各异的大小岛屿上。我们发现Phacidium响应补丁大小和资源密度，更改了分散分配的时间和速率。在资源较小的岛屿上，Phacidium到达斑块边缘后急剧增加了扩散分配。如果资源密度足够的话，在较大的资源岛上，Phacidium在到达岛屿边缘之前就开始分配分散资源，这暗示了额外的绝对总资源水平提示。这些结果与切换到空中传播分配的两线索模型相一致：1）真菌控制的绝对资源水平，2）真菌对斑块大小的感知。如果真菌感知到补丁被完全占用，并且如果绝对资源水平超过阈值，则以较小幅度的早期移位（对冲）被认为是完全资源分配开关之间的混合。