Revealing the mechanisms of sexual isolation in a case of sympatric and parallel ecological divergence
Revealing the mechanisms of sexual isolation in a case of sympatric and parallel ecological divergence
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DOI：
10.1111/j.1095-8312.2008.00998.x
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发表时间：
2008-07-01
影响因子：
1.9
通讯作者：
Rolan-Alvarez, Emilio
中科院分区：
文献类型：
--
作者：
Conde-Padin, Paula;Cruz, Raquel;Rolan-Alvarez, Emilio
海洋潮间带蜗牛（Littorina saxatilis）的两种生态型生活在不同的微生境和海岸高度，在加利西亚岩石海岸上同时进化。由于适应差异，这些生态型在许多性状（包括大小）上有所不同。它们在两个微生境重叠的中岸相遇、选择性交配并部分杂交。据称，观察到的部分性隔离是生态型之间体型差异以及该物种大多数种群中体型选型交配的副作用。我们使用三种互补的实验方法研究了这个假设。首先，我们使用为此目的开发的两个新统计数据，研究了哪些不同的 shell 变量对现场个体性隔离的变化贡献最大：(1) 配对性隔离和 (2) r(i)，它基于皮尔逊相关系数。我们发现体型是解释性隔离的最重要特征，特别是雄性似乎是导致性隔离的关键性别。其次，我们比较了区域之间的体型选型交配：来自西班牙西北部暴露的岩石海岸种群（由于体型选型交配而显示出不完全的生殖隔离）和受保护的西班牙和瑞典种群（显示出体型选型交配，但生态形态之间没有生殖隔离）。地区之间体型选型交配的大部分差异可以通过种群内体型差异水平来显着解释。第三，我们在实验室进行了雄性选择实验，进一步表明选择主要是根据体型来进行的。这些结果证实了所提出的解释加利西亚杂种区性隔离的机制，从而支持这种情况作为平行初期物种形成的推定例子。 (C) 2008 年伦敦林奈学会。
Two ecotypes of a marine intertidal snail (Littorina saxatilis), living at different microhabitats and shore levels, have evolved in sympatry and in parallel across the Galician rocky shore. These ecotypes differ in many traits (including size) due to differential adaptation. They meet, mate assortatively, and partially hybridize at the mid shore where the two microhabitats overlap. The partial sexual isolation observed is claimed to be a side-effect of the size differences between ecotypes combined with a size assortative mating found in most populations of this species. We investigated this hypothesis using three complementary experimental approaches. First, we investigated which of the different shell variables contributed most to the variation in individual sexual isolation in the field by using two new statistics developed for that purpose: (1) pair sexual isolation and (2) r(i), which is based on the Pearson correlation coefficient. We found that size is the most important trait explaining the sexual isolation and, in particular, the males appear to be the key sex contributing to sexual isolation. Second, we compared the size assortative mating between regions: exposed rocky shore populations from north-westwern Spain (showing incomplete reproductive isolation due to size assortative mating) and protected Spanish and Swedish populations (showing size assortative mating but not reproductive isolation between ecomorphs). Most of the variation in size assortative mating between localities was significantly explained by the within-population level of variation on size. Third, we performed a laboratory male choice experiment, which further suggested that the choice is made predominantly on the basis of size. These results confirm the mechanism proposed to explain the sexual isolation in the Galician hybrid zone and thus support this case as a putative example of parallel incipient speciation. (C) 2008 The Linnean Society of London.