Drosophila sex combs as a model of evolutionary innovations.
Drosophila sex combs as a model of evolutionary innovations.
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DOI：
10.1111/j.1525-142x.2011.00507.x
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发表时间：
2011-11
影响因子：
2.9
通讯作者：
Kopp A
中科院分区：
文献类型：
--
作者：
Kopp A
动物和植物形态的多样性是由嵌套的进化创新形成的。因此，了解这些创新的遗传和分子变化是进化生物学的关键目标之一。从遗传学的角度来看，新性状的起源意味着控制其发展的新调控途径的起源。为了理解这些新途径在进化过程中是如何组装的，我们需要将相对较新的创新与一套强大的遗传和分子工具相结合的模型系统。其中一个模型是果蝇的性梳，这是一种雄性特有的形态结构，在一个相对较小的谱系中进化而来，与模型物种D有关。黑腹果蝇我们对D. melanogaster为研究性梳起源和多样化的遗传变化提供了基础。与此同时，性梳可以在微进化时间尺度上发生变化，并且在密切相关的物种之间存在差异，这为直接遗传分析和整合发育和种群遗传方法提供了机会。性梳进化与HOX和性别决定基因之间新的相互作用的起源有关。性别决定途径的活性在HOX密码子的控制下变得具有片段特异性，而HOX基因的表达变得具有性二态性。同时，HOX和性别决定基因整合到节段内的空间模式网络中，获得了新的联合下游靶点。系统发育分析表明，相似的性梳形态在不同的谱系中独立进化。在表型水平上的趋同进化反映了HOX和性别决定基因表达的趋同变化，涉及调控相互作用的独立增益和损失。然而，下游细胞分化程序在物种之间存在分歧，并且在某些谱系中，相似的成体形态由不同的形态发生机制产生。这些特征使性梳成为一个很好的模型，不仅可以研究导致其进化的遗传变化，还可以研究将DNA序列变化转化为形态多样性的细胞过程。性梳的起源和多样化提供了深入了解模块化的作用，cooption，和监管的变化在进化创新，并可以作为一个模型来理解更激烈的新奇，定义高阶类群的起源。
The diversity of animal and plant forms is shaped by nested evolutionary innovations. Understanding the genetic and molecular changes responsible for these innovations is therefore one of the key goals of evolutionary biology. From the genetic point of view, the origin of novel traits implies the origin of new regulatory pathways to control their development. To understand how these new pathways are assembled in the course of evolution, we need model systems that combine relatively recent innovations with a powerful set of genetic and molecular tools. One such model is provided by the Drosophila sex comb – a male-specific morphological structure that evolved in a relatively small lineage related to the model species D. melanogaster. Our extensive knowledge of sex comb development in D. melanogaster provides the basis for investigating the genetic changes responsible for sex comb origin and diversification. At the same time, sex combs can change on microevolutionary timescales and differ spectacularly among closely related species, providing opportunities for direct genetic analysis and for integrating developmental and population-genetic approaches. Sex comb evolution is associated with the origin of novel interactions between HOX and sex determination genes. Activity of the sex determination pathway was brought under the control of the HOX code to become segment-specific, while HOX gene expression became sexually dimorphic. At the same time, both HOX and sex determination genes were integrated into the intrasegmental spatial patterning network, and acquired new joint downstream targets. Phylogenetic analysis shows that similar sex comb morphologies evolved independently in different lineages. Convergent evolution at the phenotypic level reflects convergent changes in the expression of HOX and sex determination genes, involving both independent gains and losses of regulatory interactions. However, the downstream cell differentiation programs have diverged between species, and in some lineages similar adult morphologies are produced by different morphogenetic mechanisms. These features make the sex comb an excellent model for examining not only the genetic changes responsible for its evolution, but also the cellular processes that translate DNA sequence changes into morphological diversity. The origin and diversification of sex combs provides insights into the roles of modularity, cooption, and regulatory changes in evolutionary innovations, and can serve as a model for understanding the origin of the more drastic novelties that define higher-order taxa.