ARC Centre of Excellence in Plant Energy Biology, M315, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
BMC Evol Biol. 2013 Oct 18;13:228. doi: 10.1186/1471-2148-13-228.
Humans and insect herbivores are competing for the same food crops and have been for thousands of years. Despite considerable advances in crop pest management, losses due to insects remain considerable. The global homogenisation of agriculture has supported the range expansion of numerous insect pests and has been driven in part by human-assisted dispersal supported through rapid global trade and low-cost air passenger transport. One of these pests, is the whitefly, Bemisia tabaci, a cryptic species complex that contains some of the world's most damaging pests of agriculture. The complex shows considerable genetic diversity and strong phylogeographic relationships. One consequence of the considerable impact that members of the B. tabaci complex have on agriculture, is the view that human activity, particularly in relation to agricultural practices, such as use of insecticides, has driven the diversification found within the species complex. This has been particularly so in the case of two members of the complex, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED), which have become globally distributed invasive species. An alternative hypothesis is that diversification is due to paleogeographic and paleoclimatological changes.
The idea that human activity is driving speciation within the B. tabaci complex has never been tested, but the increased interest in fossil whiteflies and the growth in molecular data have enabled us to apply a relaxed molecular clock and so estimate divergence dates for the major lineages within the B. tabaci species complex. The divergence estimates do not support the view that human activity has been a major driver of diversification.
Our analysis suggests that the major lineages within the complex arose approximately 60-30 mya and the highly invasive MED and MEAM1 split from the rest of the species complex around 12 mya well before the evolution of Homo sapiens and agriculture. Furthermore, the divergence dates coincide with a period of global diversification that occurred broadly across the plant and animal kingdoms and was most likely associated with major climatic and tectonic events.
人类和昆虫食草动物一直在争夺相同的粮食作物，这种竞争已经持续了数千年。尽管在作物害虫管理方面取得了相当大的进展，但由于昆虫造成的损失仍然相当大。农业的全球化使许多害虫的分布范围扩大，并在一定程度上受到人类协助的扩散的推动，这种扩散是通过快速的全球贸易和低成本的空运实现的。其中一种害虫是粉虱，Bemisia tabaci，是一个包含一些世界上最具破坏性的农业害虫的隐种复合体。该复合体表现出相当大的遗传多样性和强烈的系统地理关系。B. tabaci 复合体成员对农业的影响相当大，其中一个后果是，人类活动，特别是与农业实践有关的活动，如使用杀虫剂，推动了该物种复合体内部的多样化。在该复合体的两个成员中东-小亚细亚 1 型（MEAM1）和地中海型（MED）中尤其如此，它们已成为全球分布的入侵物种。另一种假设是，多样化是由于古地理和古气候的变化。
人类活动正在推动 B. tabaci 复合体内部物种形成的观点从未得到过检验，但人们对化石粉虱的兴趣日益增加，以及分子数据的增长，使我们能够应用放松的分子钟，从而估计 B. tabaci 种复合体主要谱系的分歧日期。分歧估计不支持人类活动是多样化的主要驱动因素的观点。
我们的分析表明，该复合体中的主要谱系大约在 60-30 百万年前形成，高度入侵的 MED 和 MEAM1 与复合体的其余部分大约在 12 百万年前分化，远早于人类和农业的出现。此外，分歧日期与全球多样化时期相吻合，这一时期广泛发生在植物和动物王国，很可能与主要的气候和构造事件有关。
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