Olfactory shifts parallel superspecialism for toxic fruit in Drosophila melanogaster sibling, D-sechellia
Olfactory shifts parallel superspecialism for toxic fruit in Drosophila melanogaster sibling, D-sechellia
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DOI：
10.1016/j.cub.2005.11.075
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发表时间：
2006-01-10
期刊：
影响因子：
9.2
通讯作者：
Hansson, BS
中科院分区：
文献类型：
--
作者：
Dekker, T;Ibba, I;Hansson, BS
从配体-受体-神经元组合[1-4]到它们进入触角叶的轴突投射模式[5，6]，果蝇中的嗅觉越来越多地被理解。因此，果蝇提供了一个很好的机会来研究嗅觉系统的进化和生态动力学。我们比较了通才D. melanogaster与D. sechellia，只在巴戟天果实上产卵[7]。我们的分析表明，而水果的顶部空间是由酸为主，触角反应最强烈的己酸。D. sechellia对己酸甲酯（MeHex）表现出非常强的响应。在行为上，D。sechellia比D.黑腹菌对MeHex的高敏感性是由触角上MeHex神经元的2.5 - 3倍的过度表达和相应肾小球体积的2.9倍的一致增加来解释的。黑腹菌此外，MeHex神经元表现出对毫微微克配体的极端敏感性。相反，没有发现外周介导的位移平行D。sechellia对酸的吸引力增加。这些发现证明了进化在嗅觉回路的几个层面上起作用，介导了果蝇对对其兄弟物种有毒的水果的独特偏好[8-10]。
Olfaction in the fruit fly Drosophila melanogaster is increasingly understood, from ligand-receptor-neuron combinations [1-4] to their axonal projection patterns into the antennal lobe [5, 6]. Drosophila thus offers an excellent opportunity to study the evolutionary and ecological dynamics of olfactory systems. We compared the structure and function of the generalist D. melanogaster with that of specialist D. sechellia, which oviposits exclusively on morinda fruit [7]. Our analyses show that whereas the fruit's headspace was dominated by acids, antennae responded most strongly to hexanoates. D. sechellia exhibited an extraordinarily strong response to methyl hexanoate (MeHex). Behaviorally, D. sechellia was much more attracted to these morinda fruit volatiles than was D. melanogaster. The high sensitivity to MeHex was paralleled by a 2.5x-3x overrepresentation of MeHex neurons on the antenna and a concordant 2.9x increase in volume of the corresponding glomerulus as compared to D. melanogaster. In addition, the MeHex neuron exhibited an extreme sensitivity down to femtograms of its ligand. In contrast, no peripherally mediated shift was found paralleling D. sechellia's increased attraction to acids. These findings are a demonstration of evolution acting at several levels in the olfactory circuitry in mediating a fruit fly's unique preference for fruit toxic to its sibling species [8-10].