Trophic eggs compensate for poor offspring feeding capacity in a subsocial burrower bug
Trophic eggs compensate for poor offspring feeding capacity in a subsocial burrower bug
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DOI：
10.1098/rsbl.2010.0707
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发表时间：
2011-04-23
期刊：
影响因子：
3.3
通讯作者：
Ueno, Takatoshi
中科院分区：
文献类型：
--
作者：
Baba, Narumi;Hironaka, Mantaro;Ueno, Takatoshi
各种动物会产生无法生存的卵或称为营养卵的卵状结构，这被认为是对后代的长期母性投资。然而，人们对与其进化起源相关的生态或生理限制知之甚少。半食性亚社会穴居虫（Canthophorus niveimarginatus）的营养卵具有一些独特的特征。营养卵对于若虫的生存是必需的，没有它们，一龄若虫就会死亡。为了确定若虫死亡的原因，我们假设一龄若虫会饿死，因为它们除了营养卵之外不能吃任何东西。尽管以人工暴露的胚乳为食的一龄若虫确实存活下来，但接受完整种子的若虫无法穿透种子容器并饿死。另一种假设认为，营养卵在将中肠共生体从母亲转移到后代中发挥作用，而中肠共生体对于异翅目昆虫的生存至关重要，但该假设被拒绝，因为几乎所有若虫都保留了共生体而不以营养卵为食。这些结果表明，子代摄食能力差是若虫死亡的原因，也是促进C. niveimarginatus好奇营养卵系统进化的重要制约因素。
Various animals produce inviable eggs or egg-like structures called trophic eggs, which are presumed to be an extended maternal investment for the offspring. However, there is little knowledge about the ecological or physiological constraints associated with their evolutionary origin. Trophic eggs of the seminivorous subsocial burrower bug (Canthophorus niveimarginatus) have some unique characteristics. Trophic eggs are obligate for nymphal survival, and first-instar nymphs die without them. To identify the cause of nymphal death, we hypothesized that first-instar nymphs starve to death because they cannot feed on anything but trophic eggs. Although first-instar nymphs fed on artificially exposed endosperm did survive, nymphs that were provided with intact seed were not able to penetrate the seed vessel and starved to death. Another hypothesis that trophic eggs play a role in transferring the midgut symbiont, essential for survival in heteropteran bugs, from mother to offspring was rejected because almost all nymphs had retained the symbiont without feeding on trophic eggs. These results suggest that poor feeding capacity of the offspring is the cause of nymphal death, and the important constraint that promotes the evolution of the curious trophic egg system in C. niveimarginatus.