Parasites and mutualism function: measuring enemy-free space in a fig-pollinator symbiosis
Parasites and mutualism function: measuring enemy-free space in a fig-pollinator symbiosis
复制标题
DOI：
10.1111/j.1600-0706.2011.20179.x
复制
发表时间：
2012-11-01
期刊：
影响因子：
3.4
通讯作者：
Cook, James M.
中科院分区：
文献类型：
--
作者：
Al-Beidh, Sarah;Dunn, Derek W.;Cook, James M.
互惠关系涉及物种之间的合作，并支持几种生态系统功能。然而，互助主义者之间也存在冲突，因为他们的利益并不完全一致。此外，大多数互惠都被寄生虫利用。在这里，我们研究了合作，冲突和寄生之间的相互作用，在无花果树和它们的传粉小蜂的互惠关系。冲突的发生是因为每个无花果子房可以培育一个种子或一个传粉者后代，而无花果树直接受益于种子和传粉者后代（花粉载体），传粉者只直接受益于传粉者后代。解决冲突的机制是有争议的，但必须解释广泛的观察，传粉者在内部发展，种子在外部，无花果花层。我们最近提出了一个角色，非传粉榕小蜂（NPFWs），是天敌或竞争对手的传粉者，并通过无花果墙产卵。大多数NPFW后代在外层和中层花中发育，表明内层花为传粉者后代提供了无天敌的空间。在这里，我们测试的假设，NPFWs不能达到内部的花，通过测量黄蜂和无花果形态在特定的时间NPFW攻击领域。结果表明，三种榕小蜂对传粉昆虫的寄生率分别为34.73%、75.92%和82.97%。同时，Eukobelea和Pseudidarnes gall-formers，尽管有较短的产卵器，可以访问几乎所有的无花果花（9399%和100%），因为他们攻击较小的（年轻）无花果果实。我们从产卵黄蜂的机制研究结果支持的空间格局内的榕小蜂后代分离表明，内胚珠为传粉昆虫提供了无天敌的空间。这可能有助于互利共生的稳定性，帮助选择传粉者，以避免产卵，他们可能会被寄生。这些外部的花然后保持自由发展为种子，促进互惠共生的持久性。
Mutualisms involve cooperation between species and underpin several ecosystem functions. However, there is also conflict between mutualists, because their interests are not perfectly aligned. In addition, most mutualisms are exploited by parasites. Here, we study the interplay between cooperation, conflict and parasitism in the mutualism between fig trees and their pollinator wasps. Conflict occurs because each fig ovary can nurture either one seed or one pollinator offspring and, while fig trees benefit directly from seeds and pollinator offspring (pollen vectors), pollinators only benefit directly from pollinator offspring. The mechanism(s) of conflict resolution is debated, but must explain the widespread observation that pollinators develop in inner, and seeds in outer, layers of fig flowers. We recently suggested a role for non-pollinating figs wasps (NPFWs) that are natural enemies or competitors of the pollinators and lay their eggs through the fig wall. Most NPFW offspring develop in outer and middle layer flowers, suggesting that inner flowers provide enemy-free space for pollinator offspring. Here, we test the hypothesis that NPFWs cannot reach inner flowers, by measuring wasp and fig morphology at the species-specific times of NPFW attack in the field. We found that three species of Sycoscapter and Philotrypesis wasps that parasitise pollinators could reach 3473%, 7592% and 8297% of fig ovaries, respectively. Meanwhile, Eukobelea and Pseudidarnes gall-formers, despite having shorter ovipositors, can access almost all fig flowers (9399% and 100%), because they attack smaller (younger) fig fruits. Our mechanistic results from ovipositing wasps support spatial patterns of wasp offspring segregation within figs to suggest that inner ovules provide enemy-free-space for pollinators. This may contribute to mutualism stability by helping select for pollinators to avoid laying eggs where they are likely to be parasitised. These outer flowers then remain free to develop as seeds, promoting mutualism persistence.