Partner abundance controls mutualism stability and the pace of morphological change over geologic time
Partner abundance controls mutualism stability and the pace of morphological change over geologic time
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DOI：
10.1073/pnas.1616837114
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发表时间：
2017-04-11
影响因子：
11.1
通讯作者：
Renner, Susanne S.
中科院分区：
文献类型：
--
作者：
Chomicki, Guillaume;Renner, Susanne S.
涉及专业伙伴之间共生的互惠关系可能比通才之间的互惠关系更稳定，理论模型预测，在许多互惠关系中，伙伴对直接参与互动的特征进行互惠稳定选择。一个推论是，互惠互利的崩溃应该会增加形态进化的速度。在这里，我们使用最大的蚂蚁植物分支(Hydnophytinae)，对互惠共生的蚂蚁共生体具有不同程度的专化性，以研究互惠共生破裂的生态背景，以及与共生相关的关键特征--omatium入口孔大小--的响应，该特征根据共生体的大小过滤共生体。我们的分析支持互惠理论的三个预测。首先，所有12项损失显然只发生在通才共生状态下。第二，共生损失发生在共生体稀少的地方，在我们的系统中，在高海拔地区。第三，在专门性共生物种中，洞穴的大小几乎没有变化，但一旦与蚂蚁的共生被打破，洞穴的大小就会迅速进化，一张形态图揭示了洞穴进化的热点聚集在高海拔地区。我们的研究表明，互惠策略深刻地影响了相互作用中涉及的特征的形态变化的速度，并表明伙伴的相对丰富度的变化可能经常推动通才互惠关系向自主的逆转。
Mutualisms that involve symbioses among specialized partners may be more stable than mutualisms among generalists, and theoretical models predict that in many mutualisms, partners exert reciprocal stabilizing selection on traits directly involved in the interaction. A corollary is that mutualism breakdown should increase morphological rates of evolution. We here use the largest ant-plant clade (Hydnophytinae), with different levels of specialization for mutualistic ant symbionts, to study the ecological context of mutualism breakdown and the response of a key symbiosis-related trait, domatium entrance hole size, which filters symbionts by size. Our analyses support three predictions from mutualism theory. First, all 12 losses apparently only occur from a generalist symbiotic state. Second, mutualism losses occurred where symbionts are scarce, in our system at high altitudes. Third, domatium entrance hole size barely changes in specialized symbiotic species, but evolves rapidly once symbiosis with ants has broken down, with a "morphorate map" revealing that hotspots of entrance hole evolution are clustered in high-altitude areas. Our study reveals that mutualistic strategy profoundly affects the pace of morphological change in traits involved in the interaction and suggests that shifts in partners' relative abundances may frequently drive reversions of generalist mutualisms to autonomy.