Darst Catherine R, Menéndez-Guerrero Pablo A, Coloma Luis A, Cannatella David C
Section of Integrative Biology, Texas Memorial Museum, University of Texas, Austin, Texas 78712, USA.
Am Nat. 2005 Jan;165(1):56-69. doi: 10.1086/426599. Epub 2004 Nov 12.
Defensive mechanisms, including noxious or toxic substances, are favored by predation-driven natural selection. The acquisition of noxious/toxic substances can be either endogenous, in which the substances are produced by the organism, or exogenous, in which the substances are produced by another organism and are sequestered. Evidence indicates that the defensive skin alkaloids of Neotropical poison frogs (Dendrobatidae) have an exogenous source: a diet of ants and other small alkaloid-containing arthropods, which we term the diet-toxicity hypothesis. A critical prediction of the diet-toxicity hypothesis is that independent origins of dietary specialization will be found to be correlated with independent origins of skin alkaloids. We tested this prediction in an integrated framework using comparative methods with new and published data on feeding ecology and chemical defense for 15 species of dendrobatids in five genera. We found a significant correlation between alkaloid profiles and degree of dietary specialization. This reveals a recurring association of dietary specialization and alkaloid sequestration in dendrobatids, which suggests parallel evolutionary trends in the origins of defensive mechanisms.
包括有毒或有害物质在内的防御机制受到捕食驱动的自然选择的青睐。获取有毒/有害物质既可以是内源性的，即由生物体自身产生这些物质，也可以是外源性的，即由其他生物体产生并被生物体隔离这些物质。有证据表明，新热带区毒蛙（箭毒蛙科）的防御性皮肤生物碱有外源性来源：以蚂蚁和其他含生物碱的小型节肢动物为食，我们将此称为饮食毒性假说。饮食毒性假说的一个关键预测是，饮食特化的独立起源将被发现与皮肤生物碱的独立起源相关。我们使用比较方法，在一个综合框架中，利用新的和已发表的关于五个属的15种箭毒蛙的觅食生态学和化学防御的数据，对这一预测进行了检验。我们发现生物碱谱与饮食特化程度之间存在显著相关性。这揭示了箭毒蛙中饮食特化和生物碱隔离之间反复出现的关联，这表明防御机制起源中存在平行进化趋势。
