生物学家一直认为植物和授粉昆虫间的相互作用加速了进化中的演变、提高了物种的多样性。然而，新的研究成果表明植物与授粉者们之间的相互作用并不是如之前所想象的那样能够增加生物的多样性，相反的，在某种情况下是减少的。
新发现显示Joshua tree和为其授粉的蛾，如Tegeticula Synthetica之间的协同进化并没有像之前人们想象的那样促进多样性增加，反而是使其减少的。
这项发表在《进化生物学期刊》（Journal of Evolutionary Biology） 上的研究结果显示位于Mojave Desert的一种当地最有特色的植物——Joshua tree——并不像预期中的那样具有生物多样性。如果没有某种特殊的蛾为其的花朵授粉的话，Joshua tree将无法产生种子。之前的研究结果显示生物多样性存在于Joshua tree和为它进行授粉的蛾之间：那些具有很长的产卵器的蛾往往喜欢具有较大花朵，而产卵器较小的蛾则倾向于较小的花朵。因此，生物学家们猜测蛾的这种特 点与当地显花植物相互适应并达到繁殖的目的。但是在结合数学建模以及野外观察之后，研究者们发现物种间的生物多样性并不显著，同时也没有证据能表明当地的 蛾适应当地的Joshua tree。
“我们之前就已经观察到了两种类型的蛾：较大的蛾偏好较大的花朵，而较小的蛾则喜欢较小的花朵。但是当我们试图去解释这种差异时，我们发现没有证据说明蛾已经适应了这些花。”负责这项研究的来自于国家数学和生物综合研究所的博士后William Godsoe说道。（生物谷Bioon.com）
生物谷推荐原文出处：
J Evol Biol. 2010 Dec;23(12):2739-46.
Absence of population-level phenotype matching in an obligate pollination mutualism.
Godsoe W, Yoder JB, Smith CI, Drummond CS, Pellmyr O.
National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN 37996-1527, USA. godsoe@nimbios.org
Abstract
Coevolution is thought to promote evolutionary change between demes that ultimately results in speciation. If this is the case, then we should expect to see similar patterns of trait matching and phenotypic divergence between populations and between species in model systems for coevolution. As measures of divergence are frequently only available at one scale (population level or taxon level), this contention is rarely tested directly. Here, we use the case of co-divergence between different varieties of Joshua tree Yucca brevifolia (Agavaceae) and their obligate pollinators, two yucca moths (Tegeticula spp. Prodoxidae), to test for trait matching between taxa and among populations. Using model selection, we show that there is trait matching between mutualists at the taxon level, but once we account for differences between taxa, there is no indication of trait matching in local populations. This result differs from similar studies in other coevolving systems. We hypothesize that this discrepancy arises because coevolution in obligate mutualisms favours divergence less strongly than coevolution in other systems, such as host–parasite interactions.
