Testing Finch's hypothesis: The role of organismal modularity on the escape from actuarial senescence
Testing Finch's hypothesis: The role of organismal modularity on the escape from actuarial senescence
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DOI：
10.1111/1365-2435.13486
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发表时间：
2020-01-01
影响因子：
5.2
通讯作者：
Salguero-Gomez, Roberto
中科院分区：
文献类型：
--
作者：
Bernard, Connor;Compagnoni, Aldo;Salguero-Gomez, Roberto
直到最近，衰老还被认为是一种普遍现象。衰老的进化理论预测，任何生物体都无法逃脱导致死亡风险增加和/或生育能力随年龄增长而下降的生理衰退。然而，在过去的十年里，动物和植物中出现的证据推翻了这种预测。研究人员目前正在寻求对观察到的衰老轨迹变化的机制解释。我们认为，关于衰老必然性的历史观点部分是由于其经典理论的发展，这些理论主要针对单一生物体。在单一种中，资源和功能的整合程度高，成虫的大小是确定的。相比之下，模块化生物的结构是不确定的，并建立在重复的模块上。在水螅（hydra spp.）和木腐灌木Larrea tridentata等物种中分离出的死亡风险可能解释了它们的零衰老甚至负衰老。三十年前，凯莱布·芬奇假设，具有区分风险能力的物种可能会避免衰老。在这里，我们首先回顾了生物体在其结构背景下减缓甚至避免衰老的证据，沿着统一性-模块化的连续体。然后，我们使用开放访问的数据库来比较分析衰老的各个时刻，并将寿命与解剖模块化程度联系起来。我们的分析比较了138种植物和151种动物的衰老速度，以及其中一部分动物衰老的形状。我们的比较分析表明，模块化程度更高的植物物种确实比单一的植物物种更容易避免衰老。模块化在动物衰老中的作用尚不清楚。鉴于芬奇的假设在大量植物物种中得到了新的支持，而在动物身上却没有那么确凿的发现，我们确定了新的研究方向。我们强调与年龄相关的死亡率因素有关的机会。其他需要进一步研究的领域包括模块化在内分泌作用中的作用，以及模块化解剖的成本。
Until recently, senescence was assumed to be a universal phenomenon. Evolutionary theories of senescence predict that no organism may escape the physiological decline that results in an increase in mortality risk and/or decline in fertility with age. However, evidence both in animals and plants has emerged in the last decade defying such predictions. Researchers are currently seeking mechanistic explanations for the observed variation in ageing trajectories. We argue that the historical view on the inevitability of senescence is due, in part, to the development of its classical theories, which targeted primarily unitary organisms. In unitary species, the integration of resources and functions is high, and adult size is determined. In contrast, the architecture of modular organisms is indeterminate and built upon repeated modules. The isolation of mortality risk in species like hydra (Hydra spp.) or creosote brush Larrea tridentata may explain their null or even negative senescence. Caleb Finch hypothesized three decades ago that species with the ability to compartmentalize risk may escape senescence. Here, we first review the evidence on organisms that slow down or even avoid senescence in the context of their architecture, along a continuum of unitarity-modularity. Then, we use open-access databases to comparatively analyse various moments of senescence and link longevity to the degree of anatomical modularity. Our analysis compares the pace of senescence across 138 plants and 151 animals, and the shape of senescence across a subset of these. Our comparative analysis reveals that plant species that are more modular do indeed tend to escape from senescence more often than those that are unitary. The role of modularity in animal senescence is less clear. In light of novel support for Finch's hypothesis across a large diversity of plant species, and with less conclusive findings in animals, we identify new research directions. We highlight the opportunities related to age-dependent mortality factors. Other areas for further research include the role of modularity in relation to endocrine actions, and the costs of modular anatomies.