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Abstract：
Heterostyly is a sex polymorphism that has challenged evolutionary biologists ever since Darwin. One of the lineages where heterostyly and related stylar conditions appear more frequently is Linum (Linaceae). This group is particularly suitable for testing competing hypotheses about ancestral and transitional stages on the evolutionary building up of heterostyly. We generated a phylogeny of Linum based on extensive sampling and plastid and nuclear DNA sequences, and used it to trace the evolution of character states of style polymorphism. We also revised available data on pollination, breeding systems, and polyploidy to analyse their associations. Our results supported former phylogenetic hypotheses: the paraphyly of Linum and the non-monophyly of current taxonomic sections. Heterostyly was common in the genus, but appeared concentrated in the Mediterranean Basin and the South African Cape. Ancestral character state reconstruction failed to determine a unique state as the most probable condition for style polymorphism in the genus. In contrast, approach herkogamy was resolved as ancestral state in some clades, giving support to recent hypotheses. Some traits putatively related to heterostyly, such as life history and polyploidy, did show marginal or non-significant phylogenetic correlation, respectively. Although pollinator data are limited, we suggest that beeflies are associated with specific cases of heterostyly. The consistent association between style polymorphism and heteromorphic incompatibility points to ecological factors as drivers of the multiple evolution of style polymorphism in Linum. Albeit based on limited evidence, we hypothesised that specialised pollinators and lack of mating opportunities drive evolution of style polymorphism and loss of the polymorphism, respectively.
摘要：
异型是一种性别多态性，自达尔文以来一直挑战着进化生物学家。Linum（Linaceae）是异型和相关风格条件更频繁出现的谱系之一。该组特别适合测试有关祖先和过渡阶段的竞争性假设。我们基于广泛的采样以及质体和核DNA序列产生了Linum的系统发育，并用它来追踪样式多态性的字符状态的演变。我们还修订了现有的授粉数据，育种系统,和多倍体分析它们的关联。我们的结果支持以前的系统发育假设：Linum的亲缘性和当前分类学部分的非单生性。杂种在属中很常见，但似乎集中在地中海盆地和南非海角。祖先性格状态重建未能确定唯一状态是该属中最可能的样式多态性条件。相比之下,Herkogamy的方法在某些分支中被解决为祖先状态，支持最近的假设。一些假定与异样相关的特征，比如生活史和多倍体，确实显示出边缘或非显著的系统发育相关性，分别。虽然传粉者数据有限，我们认为，蜂蝇与异样的特定病例有关。风格多态性与异形不相容性之间的一致关联表明，生态因素是Linum风格多态性多重进化的驱动因素。尽管基于有限的证据，我们假设，专门的传粉者和缺乏交配机会驱动风格多态性的进化和多态性的丧失，分别。
