Highly invasive tree species are more dependent on mutualisms.
Highly invasive tree species are more dependent on mutualisms.
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DOI：
10.1002/ecy.2997
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发表时间：
2020-01
期刊：
影响因子：
4.8
通讯作者：
J. Moyano;M. Rodríguez-Cabal;Martin A. Nuñez
中科院分区：
文献类型：
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作者：
J. Moyano;M. Rodríguez-Cabal;Martin A. Nuñez
为什么有些物种会成为入侵物种，而另一些则不会，这仍然是一个难以捉摸的问题。有人提出，入侵物种应该减少对互惠关系的依赖，因为它们的传播将较少受到互惠伙伴的可用性的限制。我们用松属验证了这一观点，松属的入侵程度在物种水平上是已知的（与种子大小高度负相关），并且与外生菌根真菌（EMF）形成了强制性的互惠关系。菌根依赖性被定义为植物需要菌根真菌来显示最大生长的程度。在这方面，我们使用植物对菌根真菌的生长反应作为菌根依赖性的代理。我们利用34种松树的1206份对比资料评估了松树物种对EMF的响应性，并将这些数据与松树物种入侵性数据进行了匹配。令人惊讶的是，我们发现更具侵入性的物种更多地依赖于相互作用（EMF）。种子越小的物种的幼苗生长越受益于共生关系，表明相互依赖程度越高。对EMF的高度依赖可能是一种策略的一部分，在这种策略中，小种子物种产生更多的种子，这些种子可以进一步传播，而这些物种只有在菌根真菌的促进下才有可能建立起来。相反，大种子物种对EMF的依赖性较低，这可能与它们在建立过程中对应激条件的耐受性有关。然而，大种子的有限传播可能会限制这些物种的传播。我们提出了强有力的证据，反对生态学中一个古老的信念，即更多依赖于共生关系的物种更不容易入侵，并提出在某些情况下，更依赖于共生关系可以增加传播能力。
Why some species become invasive while others do not remains an elusive question. It has been proposed that invasive species should depend less on mutualisms, because their spread would then be less constrained by the availability of mutualistic partners. We tested this idea with the genus Pinus, whose degree of invasiveness is known at the species level (being highly and negatively correlated with seed size) and which forms obligate mutualistic associations with ectomycorrhizal fungi (EMF). Mycorrhizal dependence is defined as the degree to which a plant needs the mycorrhizal fungi to show the maximum growth. In this regard, we use plant growth response to mycorrhizal fungi as a proxy for mycorrhizal dependence. We assessed the responsiveness of Pinus species to EMF using 1206 contrasts published on 34 species, and matched these data with data on Pinus species invasiveness. Surprisingly, we found that species which are more invasive depend more on mutualisms (EMF). Seedling growth of species with smaller seeds benefited more from mutualisms, indicating a higher dependence. A higher reliance on EMF could be part of a strategy in which small-seeded species produce more seeds that can disperse further, and these species are likely to establish only if facilitated by mycorrhizal fungi. On the contrary, big seeded species showed a lower dependence on EMF, which may be explained by their tolerance to stressful conditions during establishment. However, the limited dispersal of larger seeds may limit the spread of these species. We present strong evidence against a venerable belief in ecology that species that rely more on mutualisms are less prone to invade, and suggest that in certain circumstances greater reliance on mutualists can increase spread capacity.