Longevity, early emergence and body size in a pollinating fig wasp - implications for stability in a fig-pollinator mutualism
Longevity, early emergence and body size in a pollinating fig wasp - implications for stability in a fig-pollinator mutualism
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DOI：
10.1111/j.1365-2656.2008.01416.x
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发表时间：
2008-09-01
影响因子：
4.8
通讯作者：
Cook, James M.
中科院分区：
文献类型：
--
作者：
Dunn, Derek W.;Yu, Douglas W.;Cook, James M.
1.无花果树（Ficus）仅由Agaonid黄蜂授粉，其幼虫也会虫瘿无花果胚珠。每个胚珠要么发育成种子（授粉时），要么发育成黄蜂（当卵也产在里面时），但不是两者兼而有之。产卵蜂（foundresses）喜欢靠近封闭花序（syconium或“fig”）中心的胚珠，将胚珠留在外壁附近发育成种子。黄蜂和种子的这种空间分层确保了双方的繁殖，从而使互利共生持续下去。然而，对此负责的机制仍然不明。理论表明，foundresses将寻找越来越罕见的内胚珠，忽略外胚珠，只要产卵在外胚珠是足够慢和/或如果内胚珠赋予更大的健身黄蜂。因此，无花果传粉者互利共生可以通过对foundresses的强时间约束和胚珠位置变化的后代适应度梯度来稳定。雌性榕小蜂在没有雄性协助的情况下不能离开它们的虫瘿。我们发现，女性在外部胚珠是不太可能被释放。因此，内部胚珠对母种有附加价值，因为它们的雌性后代更容易交配和分散。对于那些确实出现的后代，瘿位置（内/外）和身体大小并没有影响雌性传粉者离开隐孢子虫的顺序，也没有早期出现的黄蜂享受增加的寿命。我们还发现，当获得水分时，雌性黄蜂的寿命几乎翻了一番。我们认为，冲突解决无花果传粉者互惠可能因此受到热带季节性的影响，因为黄蜂可能不太能够过度利用胚珠在干燥时期，由于时间的限制。
1. Fig trees (Ficus) are pollinated only by agaonid wasps, whose larvae also gall fig ovules. Each ovule develops into either a seed (when pollinated) or a wasp (when an egg is also laid inside) but not both.2. Ovipositing wasps (foundresses) favour ovules near the centre of the enclosed inflorescence (syconium or 'fig'), leaving ovules near the outer wall to develop into seeds. This spatial stratification of wasps and seeds ensures reproduction in both partners, and thereby enables mutualism persistence. However, the mechanism(s) responsible remain(s) unknown.3. Theory shows that foundresses will search for increasingly rare inner ovules and ignore outer ovules, as long as ovipositing in outer ovules is sufficiently slow and/or if inner ovules confer greater fitness to wasps. The fig-pollinator mutualism can therefore be stabilized by strong time constraints on foundresses and by offspring fitness gradients over variation in ovule position.4. Female fig wasps cannot leave their galls without male assistance. We found that females in outer ovules were unlikely to be released. Inner ovules thus have added value to foundresses, because their female offspring are more likely to mate and disperse.5. For those offspring that did emerge, gall position (inner/outer) and body size did not influence the order in which female pollinators exited syconia, nor did early emerging wasps enjoy increased life spans.6. We also found that the life spans of female wasps nearly doubled when given access to moisture. We suggest that conflict resolution in the fig-pollinator mutualism may thus be influenced by tropical seasonality, because wasps may be less able to over-exploit ovules in dry periods due to time constraints.