Department of Systematic and Evolutionary Botany, Faculty Center of Biodiversity, University of Vienna, Austria.
Ann Bot. 2012 Feb;109(2):351-63. doi: 10.1093/aob/mcr291. Epub 2011 Nov 23.
Studies examining patterns and processes of speciation in South America are fewer than in North America and Europe. One of the least well documented processes has been progenitor-derivative speciation. A particularly instructive example occurs in the southern Andes in the genus Pozoa (Apiaceae, Azorelloideae), which consists of only two diploid outcrossing species, the widespread P. coriacea and the geographically and ecologically restricted P. volcanica. This paper tests the hypothesis that the latter species originated from the former through local geographical and ecological isolation by progenitor-derivative speciation.
DNA sequences were analysed from Pozoa and the related South American genera Asteriscium, Eremocharis and Gymnophyton from non-coding regions of the plastid genome, ndhF-rpl32 and rpl32-trnL, plus incorporation of previously reported rpl16 intron and trnD-trnT intergenic spacer sequences. Amplified fragment length polymorphism (AFLP) data from 105 individuals in 21 populations throughout the entire range of distribution of the genus were used for estimation of genetic diversity, divergence and SplitsTree network analysis. Ecological factors, including habitat and associated species, were also examined.
Pozoa coriacea is more similar genetically to the outgroup genera, Asteriscium and Eremocharis, than is P. volcanica. At the population level, only P. volcanica is monophyletic, whereas P. coriacea is paraphyletic. Analyses of genetic differentiation among populations and genetic divergence and diversity of the species show highest values in P. coriacea and clear reductions in P. volcanica. Pozoa coriacea occurs in several types of high elevation habitats, whereas P. volcanica is found only in newly formed open volcanic ash zones.
All facts support that Pozoa represents a good example of progenitor-derivative speciation in the Andes of southern South America.
与北美和欧洲相比，研究南美的物种形成模式和过程的研究较少。其中记录最少的过程之一是祖裔物种形成。在南美洲南部的 Pozoa 属（伞形科，Azorelloideae）中，有一个特别有启发性的例子，该属仅由两个二倍体异交种组成，广泛分布的 P. coriacea 和地理上和生态上受限的 P. volcanica。本文检验了以下假设：即通过祖裔物种形成导致的局部地理和生态隔离，后者是从前者起源的。
从 Pozoa 和相关的南美属 Asteriscium、Eremocharis 和 Gymnophyton 中分析了质体基因组非编码区 ndhF-rpl32 和 rpl32-trnL 的 DNA 序列，以及之前报道的 rpl16 内含子和 trnD-trnT 基因间隔序列。利用整个属分布范围内 21 个种群的 105 个个体的扩增片段长度多态性（AFLP）数据，估算了遗传多样性、分化和 SplitsTree 网络分析。还检查了生态因素，包括生境和相关物种。
Pozoa coriacea 在遗传上与外类群属 Asteriscium 和 Eremocharis 更为相似，而不是 P. volcanica。在种群水平上，只有 P. volcanica 是单系的，而 P. coriacea 是并系的。对种群间遗传分化、物种遗传分化和多样性的分析表明，P. coriacea 的值最高，而 P. volcanica 的值明显降低。Pozoa coriacea 出现在几种高海拔生境中，而 P. volcanica 仅出现在新形成的开阔火山灰区。
所有事实都支持 Pozoa 是南美的安第斯山脉祖裔物种形成的一个很好的例子。
