José J, Puma-Villanueva W J, Von Zuben F J, Diniz-Filho J A F
Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brasil.
Genet Mol Res. 2008;7(4):1327-43. doi: 10.4238/vol7-4gmr512.
The amount of genetic variability in species and populations has been mainly related to microevolutionary forces operating in natural populations and the influence of phylogenetic processes for the distribution of genetic variability has been neglected. To investigate how the current genetic variability distribution depends on the genetic variability of ancestral species, we simulated the evolution of heterozygosity on a pre-determined phylogeny under three neutral models of evolution: genetic drift, drift vs mutation and drift vs migration. The distribution of genetic variability resulting from the simulations was used to estimate the phylogenetic signal by the phylogenetic comparative method of autocorrelation. Phylogenetic signal in genetic variability was observed for each of the three models, and its intensity was generally higher and persisted longer when forces of drift, mutation and migration were reduced. The prediction of a phylogenetic signal in genetic variability has consequences for: population genetics, which must consider biological processes acting at the species level influencing the amount and distribution of genetic variability; the macroevolutionary theory, by giving a theoretical basis for species selection by suggesting a heritability of genetic variability between species, and the meta-analyses of genetic variability, which must deal with the non-independence of species. The patterns observed in phylogenetic signal produced by different models of evolution can be used further to compare with data obtained from molecular markers. This is the first study that analyzes the theoretical expectations for the existence of a phylogenetic signal in a population genetic trait.
物种和种群中的遗传变异性数量主要与自然种群中起作用的微进化力量相关，而系统发育过程对遗传变异性分布的影响一直被忽视。为了研究当前的遗传变异性分布如何依赖于祖先物种的遗传变异性，我们在三种中性进化模型下，即在遗传漂变、漂变与突变以及漂变与迁移模型下，在预先确定的系统发育树上模拟了杂合性的进化。模拟产生的遗传变异性分布通过自相关的系统发育比较方法用于估计系统发育信号。在这三种模型中的每一种中都观察到了遗传变异性中的系统发育信号，并且当漂变、突变和迁移的力量减弱时，其强度通常更高且持续时间更长。遗传变异性中系统发育信号的预测对以下方面有影响：种群遗传学，它必须考虑在物种水平上起作用的影响遗传变异性数量和分布的生物学过程；宏观进化理论，通过暗示物种间遗传变异性的可遗传性为物种选择提供理论基础；以及遗传变异性的元分析，它必须处理物种的非独立性。不同进化模型产生的系统发育信号中观察到的模式可进一步用于与从分子标记获得的数据进行比较。这是第一项分析种群遗传性状中系统发育信号存在的理论预期的研究。
