Dobler Susanne, Mardulyn Patrick, Pasteels Jacques M, Rowell-Rahier Martine
Zoologisches Institut, Universität Basel, Rheinsprung 9, CH-4051, Basel, Switzerland.
Laboratoire de Biologie Animale et Cellulaire, Université Libre de Bruxelles, 50 Av. F.D. Roosevelt, B-1050, Bruxelles, Belgium.
Evolution. 1996 Dec;50(6):2373-2386. doi: 10.1111/j.1558-5646.1996.tb03625.x.
Insect-plant interactions have played a prominent role in investigating phylogenetic constraints in the evolution of ecological traits. The patterns of host association among specialized insects have often been described as highly conservative, yet not all specialized herbivorous insect lineages display the same degree of fidelity to their host plants. In this paper, we present an estimate of the evolutionary history of the leaf beetle genus Oreina. This genus displays an amazing flexibility in several aspects of its ecology and life history: (1) host plant switches in Oreina occurred between plant families or distantly related tribes within families and thereby to more distantly related plants than in several model systems that have contributed to the idea of parallel cladogenesis; (2) all species of the genus are chemically defended, but within the genus a transition between autogenous production of defensive toxins and sequestration of secondary plant compounds has occurred; and (3) reproductive strategies in the genus range from oviparity to viviparity including all intermediates that could allow the gradual evolution of viviparity. Cladistic analysis of 18 allozyme loci found two most parsimonious trees that differ only in the branching of one species. According to this phylogeny estimate, Oreina species were originally associated with Asteraceae, with an inclusion of Apiaceae in the diet of one oligophagous species and an independent switch to Apiaceae in a derived clade. The original mode of defense appears to be the autogenous production of cardenolides as previously postulated; the additional sequestration of pyrrolizidine alkaloids could have either originated at the base of the genus or have arisen three times independently in all species that switched to plants containing these compounds. Viviparity apparently evolved twice in the genus, once without matrotrophy, through a retention of the eggs inside the female's oviducts, and once in combination with matrotrophy. We hypothesize that the combination of autogenous defense and a life history that involves mobile externally feeding larvae allowed these beetles to switch host plants more readily than has been reported for highly conservative systems.
昆虫与植物的相互作用在研究生态性状进化中的系统发育限制方面发挥了重要作用。专食性昆虫之间的寄主关联模式通常被描述为高度保守，但并非所有专食性食草昆虫谱系对其寄主植物都表现出相同程度的忠诚度。在本文中，我们给出了叶甲属奥瑞娜（Oreina）进化历史的估计。该属在其生态和生活史的几个方面表现出惊人的灵活性：（1）奥瑞娜属内的寄主植物转换发生在植物科之间或科内亲缘关系较远的族之间，因此转换到的植物比一些促成平行分支进化概念的模式系统中的植物亲缘关系更远；（2）该属所有物种都有化学防御，但在属内发生了从自体产生防御毒素到螯合次生植物化合物的转变；（3）该属的繁殖策略从卵生到胎生，包括所有可能允许胎生逐渐进化的中间类型。对18个等位酶位点的分支分析发现了两棵最简约树，它们仅在一个物种的分支上有所不同。根据这个系统发育估计，奥瑞娜属物种最初与菊科相关联，一种寡食性物种的食物中包含伞形科植物，并且在一个衍生分支中独立地转换到了伞形科。最初的防御模式似乎如先前推测的那样是自体产生强心苷；额外螯合吡咯里西啶生物碱可能要么起源于该属基部，要么在所有转换到含有这些化合物植物的物种中独立出现了三次。胎生显然在该属中进化了两次，一次没有母体营养，通过将卵保留在雌虫输卵管内实现，另一次与母体营养相结合。我们假设自体防御和涉及可移动的外部取食幼虫的生活史相结合，使这些甲虫比高度保守系统中所报道的更容易转换寄主植物。
