Dissertation Research: Experimental Evolution in Volvocine Algae

该项目的目的是了解推动群体voline藻类（团藻及其近亲）细胞分化进化的选择压力。一些种类的volvocine藻类有两种细胞类型：生殖细胞专门用于生殖和不育体细胞专门用于运动。物种之间的趋势表明，这种分化可能是为了应对大型殖民地繁殖成本的增加而进化的。为了检验这一假设，繁殖成本将在一个殖民volvocine的，Pleodorina starrii，人工选择的大小尺寸。不育体细胞的进化是多细胞生物起源的关键一步，允许进一步分化为许多细胞类型和复杂的身体计划的发展。不同功能细胞类型的发展使得复杂性增加，这促进了大型多细胞生物（如植物和动物）的戏剧性辐射。volvocine藻类是多细胞进化的模型系统;了解这组细胞分化的起源可以揭示这种分化是如何起源于其他群体的。此外，由于体细胞牺牲自己的繁殖来造福殖民地，因此理解索马的进化对利他主义和合作的进化具有普遍意义。

The purpose of this project is to understand the selective pressures that drove the evolution of cellular differentiation in the colonial volvocine algae (Volvox and its close relatives). Some species of volvocine algae have two cell types: germ cells specialized for reproduction and sterile somatic cells specialized for motility. Trends among species suggest that this differentiation may have evolved in response to the increasing cost of reproduction in large colonies. To test this hypothesis, costs of reproduction will be measured in a colonial volvocine alga, Pleodorina starrii, artificially selected for large and small size. The evolution of sterile somatic cells was a critical step in the origin of multicellular organisms, allowing further differentiation into many cell types and the development of complex body plans. The increase in complexity allowed by the development of different functional cell types facilitated the dramatic radiations of large multicellular organisms such as plants and animals. The volvocine algae are a model system for the evolution of multicellularity; understanding the origins of cellular differentiation in this group can shed light on how such differentiation originated in other groups. Furthermore, because somatic cells sacrifice their own reproduction to benefit the colony, understanding the evolution of soma has implications for the evolution of altruism and cooperation in general.