School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
Interdisciplinary Graduate Program in Quantitative Biosciences, Georgia Institute of Technology, Atlanta, GA, USA.
Nat Ecol Evol. 2024 May;8(5):1010-1020. doi: 10.1038/s41559-024-02367-y. Epub 2024 Mar 14.
The evolution of multicellular life spurred evolutionary radiations, fundamentally changing many of Earth's ecosystems. Yet little is known about how early steps in the evolution of multicellularity affect eco-evolutionary dynamics. Through long-term experimental evolution, we observed niche partitioning and the adaptive divergence of two specialized lineages from a single multicellular ancestor. Over 715 daily transfers, snowflake yeast were subjected to selection for rapid growth, followed by selection favouring larger group size. Small and large cluster-forming lineages evolved from a monomorphic ancestor, coexisting for over ~4,300 generations, specializing on divergent aspects of a trade-off between growth rate and survival. Through modelling and experimentation, we demonstrate that coexistence is maintained by a trade-off between organismal size and competitiveness for dissolved oxygen. Taken together, this work shows how the evolution of a new level of biological individuality can rapidly drive adaptive diversification and the expansion of a nascent multicellular niche, one of the most historically impactful emergent properties of this evolutionary transition.
多细胞生命的进化促进了进化辐射，从根本上改变了地球的许多生态系统。然而，人们对于多细胞性进化的早期步骤如何影响生态进化动力学知之甚少。通过长期的实验进化，我们观察到了从一个单一的多细胞祖先分化出来的两个专门谱系的生态位分割和适应性分歧。在超过 715 次的每日转移中，雪花酵母经历了快速生长的选择，然后是有利于更大群体大小的选择。小的和大的聚集体形成的谱系从一个同形祖先进化而来，共存了超过 4300 代，专门研究生长速度和存活率之间权衡的不同方面。通过建模和实验，我们证明了共存是由生物体大小和对溶解氧的竞争力之间的权衡来维持的。总之，这项工作表明，新的生物个体水平的进化如何能够迅速推动适应性多样化和新生多细胞生态位的扩张，这是这一进化转变中最具历史影响力的新兴特性之一。
