Figs (Ficus spp.) and fig wasps (Chalcidoidea, Agaonidae): hypotheses for an ancient symbiosis
Figs (Ficus spp.) and fig wasps (Chalcidoidea, Agaonidae): hypotheses for an ancient symbiosis
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DOI：
10.1111/j.1095-8312.1985.tb01552.x
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发表时间：
1985-09
影响因子：
1.9
通讯作者：
M. Murray
中科院分区：
文献类型：
--
作者：
M. Murray
无花果和它们的传粉榕小蜂是相互依赖的繁殖自己的种类。黄蜂通过在封闭的无花果花托（隐果）内的雌花花柱中产卵来繁殖。雌雄同株的榕果内约有一半的雌花的花柱比黄蜂的产卵器长，因此它们会产生种子而不是黄蜂幼虫。既然更长的产卵器可以使黄蜂到达更多的胚珠并存款更多的卵，那么问题就出现了，为什么更长的产卵器没有进化出来。在试图回答这个问题，四个看似合理的假设进行了检查，但每一个被证明是有问题的，在某种程度上。然后考虑到第五个假设，它提出产卵器长度的限制与相对较少的种子胚和许多agaonid幼虫的隐孢子虫的流产。有人认为，首先，这种模式的流产将选择在一个持续的时期，严重的黄蜂侵扰，因为种子将成为稀缺相对于花粉携带黄蜂。因此，无花果在种子生产上的支出增加将受到自然选择的青睐。一个更大的支出，种子会发生，如果年轻的隐孢子虫与特别沉重的黄蜂侵扰下降和保存的养分投资于隐孢子虫的后续作物含有平均水平的黄蜂幼虫和种子。只要投下小隐孢子虫的能量和营养成本很小，就可以消除产卵器较长的黄蜂的选择优势。因此，无花果和黄蜂的稳定共存是可能的。本文最后讨论了两个一般性的预测流产假说，以及如何这些可能会被测试。
Figs and their pollinating fig wasps are dependent on one another for propagation of their own kinds. The wasps reproduce by ovipositing through the styles of female flowers within the closed fig receptacles (syconia). About half of the female flowers within the syconia of monoecious figs have styles which are longer than the ovipositors of the wasp, and they will therefore produce seeds rather than wasp larvae. Since a longer ovipositor would enable a wasp to reach more ovules and deposit more eggs, the question arises at to why longer ovipositors have not evolved. In an attempt to answer this question, four seemingly plausible hypotheses are examined but each is shown to be problematical in some way. Consideration is then given to a fifth hypothesis which proposes that ovipositor length is constrained by abortion of syconia with relatively few seed embryos and many agaonid larvae. It is argued first that this pattern of abortion will be selected during a sustained period of heavy wasp infestation because seeds will then become scarce relative to pollen-carrying wasps. Increased expenditure by the fig on seed production would therefore be favoured by natural selection. A greater expenditure on seeds would occur if young syconia with exceptionally heavy wasp infestations were dropped and the saved nutrients invested in syconia of a subsequent crop containing average levels of wasp larvae and seeds. Provided that the energy and nutrient cost of dropping young syconia is small, the selective advantage to the wasp of longer ovipositors is eliminated in this way. A stable coexistence of figs and wasps is therefore possible. The paper concludes by discussing two general predictions of the abortion hypothesis, and how these may be tested.