Large-scale spatial synchrony and cross-synchrony in acorn production by two California oaks
Large-scale spatial synchrony and cross-synchrony in acorn production by two California oaks
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DOI：
10.1890/12-0940.1
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发表时间：
2013-01-01
期刊：
影响因子：
4.8
通讯作者：
Knops, Johannes M. H.
中科院分区：
文献类型：
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作者：
Koenig, Walter D.;Knops, Johannes M. H.
每年的种子产量变化很大，被称为“密集”或“密集结果”行为，是一种种群水平的现象，已知表现出地理同步延伸，至少在某些情况下，数百公里。对于这种地理上广泛的同步驱动因素，有两个主要的非排他性假设：(1)环境因素（Moran效应）和(2)树木对异交花粉的相互依赖（花粉偶联）。我们使用加州两种橡树18年的橡子生产数据，测试了与这两个假设相关的10个预测。在相隔745公里的12个地点（每个物种10个）获得了这两个物种整个分布范围的数据。总的来说，我们的研究结果有力地支持了Moran效应作为两个物种内部和之间空间同步的驱动因素的重要性。尤其令人信服的证据是，橡子生产的空间同步性与扩展到两个物种范围内的关键环境因子之间的密切一致性，以及两个物种之间显著的空间交叉同步性，尽管它们的地理生态存在相当大的差异。由于橡树是雌雄同株的，雌花与花粉生产不一定相关，因此，我们的测试没有解决花粉偶联在两性物种中的作用，花粉和花朵生产必然相关。然而，对于这里考虑的橡树物种，莫兰效应是橡子生产大规模空间同步性的关键驱动因素。
Seed production that varies greatly from year to year, known as "masting'' or "mast-fruiting'' behavior, is a population-level phenomenon known to exhibit geographic synchrony extending, at least in some cases, hundreds of kilometers. The two main nonexclusive hypotheses for the driver of such geographically extensive synchrony are (1) environmental factors (the Moran effect), and (2) the mutual dependence of trees on outcrossed pollen (pollen coupling). We tested 10 predictions relevant to these two hypotheses using 18 years of acorn production data on two species of California oaks. Data were obtained across the entire ranges of the two species at 12 sites (10 for each species) separated by up to 745 km. In general, our results provided strong support for the importance of the Moran effect as a driver of spatial synchrony in and between these two species. Particularly compelling was evidence of close concordance between spatial synchrony in acorn production and key environmental factors extending over the range of both species and significant spatial cross-synchrony between the two species, despite considerable differences in their geographical ecology. Because oaks are monoecious, female flowers are not necessarily related to pollen production, and thus, our tests do not address the role of pollen coupling in bisexual species where pollen and flower production are necessarily correlated. For the oak species considered here, however, the Moran effect is a key driver of large-scale spatial synchrony in acorn production.