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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Evolution of individuality during the transition from unicellular to multicellular life
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Evolution of individuality during the transition from unicellular to multicellular life

机译：从单细胞生命过渡到多细胞生命期间的个性进化

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Individuality is a complex trait, yet a series of stages each advantageous in itself can be shown to exist allowing evolution to get from unicellular individuals to multicellular individuals. We consider several of the key stages involved in this transition: the initial advantage of group formation, the origin of reproductive altruism within the group, and the further specialization of cell types as groups increase in size. How do groups become individuals? This is the central question we address. Our hypothesis is that fitness tradeoffs drive the transition of a cell group into a multicellular individual through the evolution of cells specialized at reproductive and vegetative functions of the group. We have modeled this hypothesis and have tested our models in two ways. We have studied the origin of the genetic basis for reproductive altruism (somatic cells specialized at vegetative functions) in the multicellular Volvox carteri by showing how an altruistic gene may have originated through cooption of a life-history tradeoff gene present in a unicellular ancestor. Second, we ask why reproductive altruism and individuality arise only in the larger members of the volvocine group (recognizing that high levels of kinship are present in all volvocine algae groups). Our answer is that the selective pressures leading to reproductive altruism stem from the increasing cost of reproduction with increasing group size. Concepts from population genetics and evolutionary biology appear to be sufficient to explain complexity, at least as it relates to the problem of the major transitions between the different kinds of evolutionary individuals.
机译：个性是一个复杂的特征，但可以证明存在着一系列有利于自身发展的阶段，这些阶段允许从单细胞个体到多细胞个体的进化。我们考虑了这一转变所涉及的几个关键阶段：群体形成的初始优势，群体内生殖利他主义的起源以及随着群体规模的扩大细胞类型的进一步专业化。小组如何成为个人？这是我们要解决的中心问题。我们的假设是，权衡取舍会通过专门针对该组生殖和营养功能的细胞的进化来驱动一个细胞组向多细胞个体的过渡。我们已经对该假设进行了建模，并以两种方式检验了我们的模型。我们通过显示单细胞祖先中存在的生命历史权衡基因的选择来证明利他基因可能是如何起源的，从而研究了利他遗传（专门用于营养功能的体细胞）的生殖利他性遗传基础的起源。其次，我们问为什么生殖利他主义和个性只在Volvoine组的较大成员中出现（认识到所有Volvoine藻类组都存在很高的亲缘关系）。我们的答案是，导致繁殖利他主义的选择性压力源于繁殖成本随群体规模的增加而增加。人口遗传学和进化生物学的概念似乎足以解释复杂性，至少因为它涉及不同种类的进化个体之间的主要转变问题。

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