A Comparative Analysis of Genetic Differentiation across Six Shared Willow Host Species in Leaf- and Bud-Galling Sawflies
A Comparative Analysis of Genetic Differentiation across Six Shared Willow Host Species in Leaf- and Bud-Galling Sawflies
复制标题
六种共有柳树寄主物种在叶虫和芽虫叶蜂中遗传分化的比较分析
作者：
Sanna A. Leppänen;T. Malm;Kaisa Värri;T. Nyman
取食植物的昆虫的遗传分化和物种形成可能是由不同植物种类和分类群施加的不同选择压力所驱动。虽然已经发现了许多与寄主相关的分化（HAD）的例子，但HAD在昆虫多样化中的总体重要性仍不清楚，因为很少有研究调查它相对于所有物种形成事件的频率。推断HAD的普遍性和重复性的一种有希望的方法是估计使用同一组寄主的多个昆虫类群的遗传分化。为此，我们测量并比较了从北欧芬诺斯坎迪亚两个重复地点的六种柳树采集的叶瘿蜂Pontania和芽瘿蜂Euura（膜翅目：叶蜂科）种群样本中线粒体COI和核ITS2序列的变异。我们在这两个物种复合体中都发现了频繁的HAD的证据，因为来自同一柳树种类的个体在线粒体和核系统发育树上往往聚在一起。尽管在假定的物种之间发现的固定差异很少，但分层AMOVA分析表明，样本中的大部分遗传变异是由寄主种类而不是采样地点所解释的。然而，在两个重点瘿蜂类群中，特定寄主种类对之间所测量到的HAD水平没有相关性。因此，我们的结果支持HAD是食草动物物种形成的核心力量这一假设，但也表明即使在相关昆虫类群的时间重叠辐射中，进化轨迹的重复性也很弱。
Genetic divergence and speciation in plant-feeding insects could be driven by contrasting selection pressures imposed by different plant species and taxa. While numerous examples of host-associated differentiation (HAD) have been found, the overall importance of HAD in insect diversification remains unclear, as few studies have investigated its frequency in relation to all speciation events. One promising way to infer the prevalence and repeatability of HAD is to estimate genetic differentiation in multiple insect taxa that use the same set of hosts. To this end, we measured and compared variation in mitochondrial COI and nuclear ITS2 sequences in population samples of leaf-galling Pontania and bud-galling Euura sawflies (Hymenoptera: Tenthredinidae) collected from six Salix species in two replicate locations in northern Fennoscandia. We found evidence of frequent HAD in both species complexes, as individuals from the same willow species tended to cluster together on both mitochondrial and nuclear phylogenetic trees. Although few fixed differences among the putative species were found, hierarchical AMOVAs showed that most of the genetic variation in the samples was explained by host species rather than by sampling location. Nevertheless, the levels of HAD measured across specific pairs of host species were not correlated in the two focal galler groups. Hence, our results support the hypothesis of HAD as a central force in herbivore speciation, but also indicate that evolutionary trajectories are only weakly repeatable even in temporally overlapping radiations of related insect taxa.
影响因子：
3.3
作者：
L. Excoffier;P. Smouse;J. Quattro
通讯作者：
L. Excoffier;P. Smouse;J. Quattro