Lommen Suzanne T E, Saenko Suzanne V, Tomoyasu Yoshinori, Brakefield Paul M
Institute of Biology, Leiden University, PO Box 9516, Leiden 2300 RA, The Netherlands.
Evol Dev. 2009 May-Jun;11(3):278-89. doi: 10.1111/j.1525-142X.2009.00330.x.
Many taxa of winged insects have independently lost the ability to fly and often possess reduced wings. Species exhibiting natural variation in wing morphology provide opportunities to investigate the genetics and developmental processes underlying the evolution of alternative wing morphs. Although many wing dimorphic species of beetles are known, the underlying mechanisms of variation are not well understood in this insect order. Here, we examine wing development of wild type and natural wingless morphs of the two-spot ladybird beetle, Adalia bipunctata. We show that both pairs of wings are distally truncated in the wingless adults. A laboratory population of the wingless morph displays heritable variation in the degree of wing truncation, reflecting reduced growth of the larval wing discs. The coexistence of variable wingless morphs supports the idea that typical monomorphic wingless insects may be the result of a gradual evolution of wing loss. Gene expression patterns in wing discs suggest that the conserved gene network controlling wing development in wild-type Adalia is disrupted in the dorsoventral patterning pathway in the wingless morphs. Previous research on several species of ant has revealed that the anteroposterior wing patterning pathway is disrupted in wingless workers. Future investigations should confirm whether interruptions in both taxa are limited to the patterning pathways found thus far, or whether there are also shared interruption points. Nevertheless, our results highlight that diverse mechanisms of development are likely to underlie the evolution of wingless insects.
许多有翅昆虫类群已独立丧失飞行能力，且翅膀往往退化。表现出翅膀形态自然变异的物种为研究替代翅膀形态进化背后的遗传学和发育过程提供了机会。虽然已知许多甲虫的翅膀存在二态性物种，但在这个昆虫目中，变异的潜在机制尚未得到很好的理解。在这里，我们研究了二斑瓢虫（Adalia bipunctata）野生型和自然无翅形态的翅膀发育。我们发现，在无翅成虫中，两对翅膀在远端都被截断。无翅形态的实验室种群在翅膀截断程度上表现出可遗传的变异，这反映了幼虫翅芽生长的减少。可变无翅形态的共存支持了这样一种观点，即典型的单态无翅昆虫可能是翅膀丧失逐渐进化的结果。翅芽中的基因表达模式表明，控制野生型二斑瓢虫翅膀发育的保守基因网络在无翅形态的背腹模式形成途径中被破坏。先前对几种蚂蚁的研究表明，无翅工蚁的前后翅膀模式形成途径被破坏。未来的研究应确认这两个类群中的中断是否仅限于迄今为止发现的模式形成途径，或者是否也存在共同的中断点。尽管如此，我们的结果突出表明，多种发育机制可能是无翅昆虫进化的基础。
