Sympatric/parapatric speciation via differential host plant utilisation in the tephritid fly Tephritis conura

绦虫被用来检验草食性昆虫同域和异域物种形成的假设。这种苍蝇以至少九种蓟属植物的种子为食，它们都是蓟属植物。同工酶分析和生态学研究表明，在等位基因频率（位点HK）、寄主吸引和幼虫存活率等方面，金丝桃和一些卷叶菊物种之间存在一定的关系。研究重点放在宿主转移的行为和种群遗传方面。我们作为模范地研究t conura人口从三个寄主植物物种,Cirsium heterophyllum, c . oleraceum和c erisithales。植物取样于纯林分和混合林分，以及几种寄主植物中只有一种受到攻击的地方。田间和实验室实验旨在测试时间开花、寄主吸引和配偶识别对生殖隔离的相对重要性。此外，还设计了实验来测试在备用宿主上的生存能力。群体遗传分析（核基因，mtDNA）用于量化生物型（宿主关联）在其繁殖和扩散行为中是稳定的还是分化的，包括与HK酶相关的可能选择。MtDNA之所以令人感兴趣，是因为雌性选择产卵地点，而谱系可能揭示植物定植的方向性。我们的目的是阐明在一个早期的，由昆虫-植物相互作用介导的物种辐射过程的分歧的因果解释。

The tephritid fly Tephritis conura is used to test hypotheses of sympatric and parapatric speciation in herbivorous insects. The fly feeds on seeds of at least nine thistle species, all of the genus Cirsium. Allozyme analyses and ecological studies indicate a relationship between T. conura and some Cirsium species with respect to allele frequencies (locus HK), host attraction and survival of larvae. The study emphasis is put on behavioural and population genetic aspects of host shifts. We exemplarily study T. conura populations from three host plant species, Cirsium heterophyllum, C. oleraceum, and C. erisithales. Plants are sampled from pure and mixed stands, and from localities where only one of several alternative host plant species is attacked. Field and laboratory experiments are designed to test the relative importance of temporal flowering, host attraction and mate recognition for reproductive isolation. Furthermore, experiments are designed to test viability on alternate hosts. Population genetic analyses (nuclear genes, mtDNA) are used to quantify whether biotypes (host associations) are stable or diverging in their reproductive and dispersal behaviours, including possible selection linked to the enzyme HK. MtDNA is of interest because females choose the oviposition site and the genealogy may reveal the directionality of plant colonisation. We aim to elucidate causal explanations for divergence in an incipient, by insect-plant interactions mediated process of species radiation.