Williams Ben P, Johnston Iain G, Covshoff Sarah, Hibberd Julian M
Department of Plant Sciences , University of Cambridge , Cambridge , United Kingdom.
Elife. 2013 Sep 28;2:e00961. doi: 10.7554/eLife.00961.
C4 photosynthesis has independently evolved from the ancestral C3 pathway in at least 60 plant lineages, but, as with other complex traits, how it evolved is unclear. Here we show that the polyphyletic appearance of C4 photosynthesis is associated with diverse and flexible evolutionary paths that group into four major trajectories. We conducted a meta-analysis of 18 lineages containing species that use C3, C4, or intermediate C3-C4 forms of photosynthesis to parameterise a 16-dimensional phenotypic landscape. We then developed and experimentally verified a novel Bayesian approach based on a hidden Markov model that predicts how the C4 phenotype evolved. The alternative evolutionary histories underlying the appearance of C4 photosynthesis were determined by ancestral lineage and initial phenotypic alterations unrelated to photosynthesis. We conclude that the order of C4 trait acquisition is flexible and driven by non-photosynthetic drivers. This flexibility will have facilitated the convergent evolution of this complex trait. DOI:http://dx.doi.org/10.7554/eLife.00961.001.
C4光合作用已在至少60个植物谱系中从祖先的C3途径独立进化而来，但与其他复杂性状一样，其进化方式尚不清楚。在这里，我们表明C4光合作用的多系出现与多种灵活的进化路径相关，这些路径可分为四个主要轨迹。我们对18个谱系进行了荟萃分析，这些谱系包含使用C3、C4或中间C3 - C4光合作用形式的物种，以参数化一个16维的表型景观。然后，我们开发并通过实验验证了一种基于隐马尔可夫模型的新颖贝叶斯方法，该方法可预测C4表型的进化方式。C4光合作用出现背后的替代进化历史由祖先谱系和与光合作用无关的初始表型改变决定。我们得出结论，C4性状获得的顺序是灵活的，并且由非光合驱动因素驱动。这种灵活性将促进这一复杂性状的趋同进化。DOI:http://dx.doi.org/10.7554/eLife.00961.001
