Meyers Lauren Ancel, Levin Donald A
Section of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA.
Evolution. 2006 Jun;60(6):1198-206.
The wide distribution of polyploidy among plants has led to a variety of theories for the evolutionary advantages of polyploidy. Here we claim that the abundance of polyploidy may be the result of a simple ratcheting process that does not require evolutionary advantages due to the biological properties of organisms. The evolution of polyploidy is a one-way process in which chromosome number can increase but not decrease. Using a simple mathematical model, we show that average ploidal level within a plant lineage can continually increase to the levels observed today, even if there are ecological or physiological disadvantages to higher ploidy. The model allowed us to estimate the average net speciation and polyploidy rates for ten angiosperm genera. Based on these estimates, the model predicts distributions of ploidal levels statistically similar to those observed in nine of the 10 genera.
多倍体在植物中的广泛分布引发了多种关于多倍体进化优势的理论。在此我们认为，多倍体的大量存在可能是一个简单的棘轮过程的结果，该过程并不因生物体的生物学特性而需要进化优势。多倍体的进化是一个单向过程，其中染色体数目只能增加而不能减少。通过一个简单的数学模型，我们表明，即使更高的倍性存在生态或生理劣势，植物谱系内的平均倍性水平仍可不断增加至如今观察到的水平。该模型使我们能够估计十个被子植物属的平均净物种形成率和多倍体率。基于这些估计，该模型预测的倍性水平分布在统计学上与十个属中九个属所观察到的分布相似。
