Ratcliff William C, Fankhauser Johnathon D, Rogers David W, Greig Duncan, Travisano Michael
School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0230, USA.
Plant Biology, University of Minnesota, St Paul, Minnesota 55108, USA.
Nat Commun. 2015 Jan 20;6:6102. doi: 10.1038/ncomms7102.
Complex life has arisen through a series of 'major transitions' in which collectives of formerly autonomous individuals evolve into a single, integrated organism. A key step in this process is the origin of higher-level evolvability, but little is known about how higher-level entities originate and gain the capacity to evolve as an individual. Here we report a single mutation that not only creates a new level of biological organization, but also potentiates higher-level evolvability. Disrupting the transcription factor ACE2 in Saccharomyces cerevisiae prevents mother-daughter cell separation, generating multicellular 'snowflake' yeast. Snowflake yeast develop through deterministic rules that produce geometrically defined clusters that preclude genetic conflict and display a high broad-sense heritability for multicellular traits; as a result they are preadapted to multicellular adaptation. This work demonstrates that simple microevolutionary changes can have profound macroevolutionary consequences, and suggests that the formation of clonally developing clusters may often be the first step to multicellularity.
复杂生命是通过一系列“重大转变”出现的，在这些转变中，以前自主的个体集合进化成一个单一的、整合的生物体。这一过程中的关键一步是更高层次进化能力的起源，但对于更高层次的实体如何起源以及获得作为个体进化的能力却知之甚少。在此，我们报告了一个单一突变，它不仅创造了一个新的生物组织层次，还增强了更高层次的进化能力。破坏酿酒酵母中的转录因子ACE2会阻止母细胞与子细胞分离，从而产生多细胞“雪花”酵母。雪花酵母通过确定性规则发育，产生几何形状确定的簇，这些簇排除了遗传冲突，并对多细胞性状表现出高广义遗传力；因此，它们预先适应了多细胞适应性。这项工作表明，简单的微进化变化可能会产生深远的宏观进化后果，并表明克隆发育簇的形成可能通常是迈向多细胞性的第一步。
