Henry Lee M, Roitberg Bernard D, Gillespie David R
Department of Biological sciences, Simon Fraser University, Burnaby, BC, V5A 1S6 Canada.
Evolution. 2008 Mar;62(3):689-99. doi: 10.1111/j.1558-5646.2007.00316.x. Epub 2007 Dec 25.
The diversity of parasitic insects remains one of the most conspicuous patterns on the planet. The principal factor thought to contribute to differentiation of populations and ultimately speciation is the intimate relationship parasites share with hosts and the potential for disruptive selection associated with using different host species. Traits that generate this diversity have been an intensely debated topic of central importance to the evolution of specialization and maintenance of ecological diversity. A fundamental hypothesis surrounding the evolution of specialization is that no single genotype is uniformly superior in all environments. This "trade-off" hypothesis suggests that negative fitness correlations can lead to specialization on different hosts as alternative stable strategies. In this study we demonstrate a trade-off in the ability of the parasitoid, Aphidius ervi, to maintain a high level of fitness on an ancestral and novel host, which suggests a genetic basis for host utilization that may limit host-range expansion in parasitoids. Furthermore, behavioral evidence suggests mechanisms that could promote specialization through induced host fidelity. Results are discussed in the context of host-affiliated ecological selection as a potential source driving diversification in parasitoid communities and the influence of host species heterogeneity on population differentiation and local adaptation.
寄生昆虫的多样性仍然是地球上最显著的模式之一。人们认为，导致种群分化并最终形成物种的主要因素是寄生虫与宿主之间的密切关系，以及与使用不同宿主物种相关的分裂选择的可能性。产生这种多样性的特征一直是一个激烈争论的核心话题，对专业化的进化和生态多样性的维持至关重要。围绕专业化进化的一个基本假设是，没有单一的基因型在所有环境中都是一致优越的。这种“权衡”假设表明，负适合度相关性可以导致作为替代稳定策略对不同宿主的专业化。在本研究中，我们证明了寄生蜂豌豆蚜（Aphidius ervi）在祖先宿主和新宿主上维持高适合度能力之间的权衡，这表明宿主利用的遗传基础可能会限制寄生蜂的宿主范围扩展。此外，行为证据表明了可以通过诱导宿主忠诚度来促进专业化的机制。我们将在宿主相关生态选择的背景下讨论这些结果，宿主相关生态选择是推动寄生蜂群落多样化的潜在来源，以及宿主物种异质性对种群分化和局部适应的影响。
