Interference competition and high temperatures reduce the virulence of fig wasps and stabilize a fig-wasp mutualism.
Interference competition and high temperatures reduce the virulence of fig wasps and stabilize a fig-wasp mutualism.
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干扰竞争和高温降低了无花果黄蜂的毒力并稳定了无花果黄蜂的互利关系
DOI：
10.1371/journal.pone.0007802
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发表时间：
2009-11-12
期刊：
影响因子：
3.7
通讯作者：
Yu DW
中科院分区：
文献类型：
--
作者：
Wang RW;Ridley J;Sun BF;Zheng Q;Dunn DW;Cook J;Shi L;Zhang YP;Yu DW
无花果树是由无花果小蜂授粉的，它们也在雌花中产卵。黄蜂的幼虫虫瘿并吃掉正在发育的种子。虽然无花果树从允许黄蜂产卵中受益，因为黄蜂的后代传播花粉，无花果必须阻止黄蜂在所有花朵中产卵，否则种子生产将停止，互利共生将灭绝。在总状榕中，我们发现很少有种子（产卵黄蜂）的隐头树（“无花果”）在夏天被开发不足（种子少、虫瘿少、空胚珠多），而在冬天被过度开发（种子少、虫瘿多、空胚珠少）。）。相反，有许多foundress的隐孢子虫产生中间数量的虫瘿和种子，无论季节如何。我们用实验来解释这些模式，从而解释这种互利关系是如何维持的。在炎热的夏天，黄蜂的寿命很短，因此不能在许多花中产卵。相比之下，冬季较低的温度允许黄蜂的寿命更长，这反过来又允许黄蜂利用大多数花朵。然而，即使在冬天，只有在碰巧有几个foundresses的syconia大多数花变成了虫瘿。在有较多的foundress的syconia中，干扰竞争降低了foundress的寿命，这降低了被擦伤的花的比例。我们进一步表明，syconia鼓励进入多个foundresses延迟气孔关闭。总之，这些因素使无花果树在黄蜂良性的冬季减少擦伤，在黄蜂应激的夏季增加擦伤（和授粉）。干扰竞争已被证明可以降低病原菌的毒力。我们的研究结果表明，干扰也保持合作，在一个经典的，合作共生，从而连接理论的毒力和互利。更一般地说，我们的研究结果揭示了如何频率依赖的人口调节可以发生在无花果黄蜂互惠，以及如何主机物种可以“设置游戏规则”，以确保互惠行为在其共生体。
Fig trees are pollinated by fig wasps, which also oviposit in female flowers. The wasp larvae gall and eat developing seeds. Although fig trees benefit from allowing wasps to oviposit, because the wasp offspring disperse pollen, figs must prevent wasps from ovipositing in all flowers, or seed production would cease, and the mutualism would go extinct. In Ficus racemosa, we find that syconia (‘figs’) that have few foundresses (ovipositing wasps) are underexploited in the summer (few seeds, few galls, many empty ovules) and are overexploited in the winter (few seeds, many galls, few empty ovules). Conversely, syconia with many foundresses produce intermediate numbers of galls and seeds, regardless of season. We use experiments to explain these patterns, and thus, to explain how this mutualism is maintained. In the hot summer, wasps suffer short lifespans and therefore fail to oviposit in many flowers. In contrast, cooler temperatures in the winter permit longer wasp lifespans, which in turn allows most flowers to be exploited by the wasps. However, even in winter, only in syconia that happen to have few foundresses are most flowers turned into galls. In syconia with higher numbers of foundresses, interference competition reduces foundress lifespans, which reduces the proportion of flowers that are galled. We further show that syconia encourage the entry of multiple foundresses by delaying ostiole closure. Taken together, these factors allow fig trees to reduce galling in the wasp-benign winter and boost galling (and pollination) in the wasp-stressing summer. Interference competition has been shown to reduce virulence in pathogenic bacteria. Our results show that interference also maintains cooperation in a classic, cooperative symbiosis, thus linking theories of virulence and mutualism. More generally, our results reveal how frequency-dependent population regulation can occur in the fig-wasp mutualism, and how a host species can ‘set the rules of the game’ to ensure mutualistic behavior in its symbionts.
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影响因子：
2.9
作者：
Denison, RF
通讯作者：
Denison, RF
DOI：
10.1073/pnas.2533483100
发表时间：
2003-12-23
影响因子：
11.1
作者：
Arnold, AE;Mejía, LC;Herre, EA
通讯作者：
Herre, EA
影响因子：
9.4
作者：
GALIL, J;EISIKOWI.D
通讯作者：
EISIKOWI.D
影响因子：
1
作者：
ASPI, J;HOIKKALA, A
通讯作者：
HOIKKALA, A
影响因子：
4.8
作者：
Dunn, Derek W.;Yu, Douglas W.;Cook, James M.
通讯作者：
Cook, James M.