Trade-offs during the development of primary and secondary sexual traits in a horned beetle
Trade-offs during the development of primary and secondary sexual traits in a horned beetle
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DOI：
10.1086/381741
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发表时间：
2004-02-01
影响因子：
2.9
通讯作者：
Nijhout, HF
中科院分区：
文献类型：
--
作者：
Moczek, AP;Nijhout, HF
发育过程中资源分配的权衡影响成体结构的最终大小，并有可能限制发育过程所能适应的进化变化的类型和幅度。当两个或更多的身体部位为了维持它们的生长和分化而竞争有限的资源池时，这种权衡就会出现。最近对几种全变性昆虫的研究表明，资源分配的权衡可能在物理上彼此靠近的组织中最为明显。在这里，我们研究了两个非常遥远的身体部位：雄性角甲虫的头角和生殖器之间的发育权衡的性质和程度。这两种结构都是由想象中的盘状组织发育而来，在幼虫发育后期经历爆炸式生长，但它们的生长起始时间不同。我们通过实验，在幼虫发育后期的几个时间点切除了通常产生雄性生殖器的前体细胞，并检查了这些雄性的角发育程度，与未经治疗和假手术的对照雄性进行了比较。我们发现，实验雄性长出了不成比例的大角。角的过表达对早期消融的反应是最弱的，在幼虫进入前蛹阶段之前生殖器盘被消融的雄性中最明显。我们的研究结果表明，即使是遥远的身体部位也可能依赖于一个共同的资源池来维持它们的生长，并且生长的相对时间可能在决定生长器官在发育过程中是否会相互影响以及影响程度方面发挥重要作用。我们用我们的发现来讨论资源分配权衡的生理原因和进化后果。
Resource allocation trade-offs during development affect the final sizes of adult structures and have the potential to constrain the types and magnitude of evolutionary change that developmental processes can accommodate. Such trade-offs can arise when two or more body parts compete for a limited pool of resources to sustain their growth and differentiation. Recent studies on several holometabolous insects suggest that resource allocation trade-offs may be most pronounced in tissues that grow physically close to each other. Here we examine the nature and magnitude of developmental trade-offs between two very distant body parts: head horns and genitalia of males of the horned scarab beetle Onthophagus taurus. Both structures develop from imaginal disklike tissues that undergo explosive growth during late larval development but differ in exactly when they initiate their growth. We experimentally ablated the precursor cells that normally give rise to male genitalia at several time points during late larval development and examined the degree of horn development in these males compared to that of untreated and sham-operated control males. We found that experimental males developed disproportionately larger horns. Horn overexpression was weakest in response to early ablation and most pronounced in males whose genital disks were ablated just before larvae entered the prepupal stage. Our results suggest that even distant body parts may rely on a common resource pool to sustain their growth and that the relative timing of growth may play an important role in determining whether, and how severely, growing organs will affect each other during development. We use our findings to discuss the physiological causes and evolutionary consequences of resource allocation trade-offs.