Evolutionary biology of the process of host shift in phytophagous ladybird beetles

1.研究了Vistintioctomaculata复合体的植食性瓢虫与寄主植物的协同进化关系。对瓢虫的同工酶和线粒体DNA的分析表明：(1)瓢虫的寄主在很短的进化时间内发生了转移，从茄科植物转移到其他科(菊科、罂粟科、小檗科等)植物上。目前被某些成员利用；(2)同种异位种群之间的遗传差异是“按距离隔离”的结果：(3)寄主专一性是共存的团头藻复合体共面成员之间的关键生殖障碍。对分布于北海道南部的寄主植物蓟的分子、形态和物候分析表明，尽管它们具有不同的形态…，但它们在遗传上非常相似更多的和生态差异表明，一个祖先物种在北海道及其周围地区经历了快速的种系辐射，可能是在冰川时期。虽然并不是所有的蓟都适合作为瓢虫的寄主植物，但瓢虫利用的蓟种并不构成一个单系群。大蓟中含有的一种物质被鉴定为果胶内酯，该物质对取食尼波尼察的蓟的侵扰具有摄食威慑作用。但这种黄酮类化合物不会引起另一种蓟类食性物种E.pustulos.研究了不同寄主植物生长性能的遗传背景，并比较了不同地理来源和寄主植物的不同种群间的生长表现。这些结果表明，随着对当地食物环境的适应，寄主植物在Vigintioctomaculata复合体的不同成员中的转移进行得非常迅速。瓢虫的低游走性可能促进了这一过程。较少

1. Coevolutionary relationships between the phytophagous ladybird beetles of the Epilachna vigintioctomaculata complex and their host plants were investigated. Analyses of allozymes and mtDNA of the ladybird beetles suggested that (1) host shift in the ladybird beetles occurred during a very short evolutionary time, from solanaceous plants to plants of other families (Asteraceae, Papaveraceae, Berberidaceae, etc.) now utilized by certain members; (2) genetic difference between conspecific allopatric populations was resulted from the "isolation by distance": and (3) host specificity functions as a crucial reproductive barrier between coexisting sympatric members of the E. vigintioctomaculata complex.2. Molecular, morphometric, and phenological analyses of thistles (Cirsium), one of the major host plants of the E. viglntioctomaculata complex, distributed in the southern part of Hokkaido revealed that they are genetically very similar to each other in spite of their distinct morphological … More and ecological differences, suggesting that an ancestral Cirsium species underwent rapid phyletic radiation in Hokkaido and surrounding areas, perhaps during the glacial period. Although not all thistles are suitable as the host plants of the ladybird beetles, thistle species utilized by the ladybird beetles did not constitute a monophyletic cluster.3. The substance contained in Cirsium kagamontanum, that act as a feeding deterrent against infestation by a thistle feeding E. niponica, was identified as pectolinarin. But this flavonoid did not induce feeding rejection by another thistle feeding species E. pustulosa.4. Genetic background of growth performance on different host plants was studied and compared between different populations of E. vigintioctolmaculata with different geographic origins and host plants.5. These results suggests that the shift of host plants in various members of the E. vigintioctomaculata complex proceeded very rapidly, as adaptation to local food environments. Low vagility of the ladybird beetles may have enhanced this process . Less