Speciation, niche differentiation and reproductive isolation in European cereal leaf beetles (Genus Oulema, Coleoptera, Chrysomelidae)

植食昆虫不仅代表了地球上的主要辐射之一，而且还构成了迄今为止同域物种形成的一些最强有力的案例。新物种形成的两个关键步骤，生态位分化和新兴物种之间的生殖隔离，在这里可以特别容易地被划定和测试。这一建议的目的是用谷物叶甲虫（Oulema spp.）作为模型系统来追踪这两个步骤。欧莱玛属包括欧洲几种禾草（禾草科）食性物种。基于外部和生殖形态的变化，有人声称，这种谷物害虫物种，O. melanopus，包括另一种隐种，O. rufocyanea。通过育种、饲养和食物选择实验的结合，我们计划确定这两种同域形式是否实际上构成了单独的物种，或者更确切地说，是目前在摄食习惯和繁殖特征上不同的早期物种。对假定的诊断特征进行形态学评分，并利用AFLP（扩增片段长度多态性）对两种形式之间的基因流动进行基因分析，将对数据进行补充。为了追踪与欧洲欧莱马物种宿主转移相关或不相关的物种形成事件的顺序，将进行基于mtDNA序列的系统发育分析。

Phytophagous insects represent not only one of the major radiations on earth but also comprise some of the strongest cases for sympatric speciation to date. Two crucial steps in the formation of new species, niche differentiation and reproductive isolation between emerging species, can especially easily be delimited and tested here. This proposal aims to trace both steps using cereal leaf beetles (Oulema spp.) as a model system. The genus Oulema comprises several grass (Graminaceae) feeding species in Europ e. Based on variation in external and genitalic morphology, it has been claimed that the cereal pest species, O. melanopus, includes a second cryptic species, O. rufocyanea. Through a combination of breeding, rearing and food choice experiments, we plan to establish whether these two sympatric forms actually constitute separate species or rather incipient species that are currently diverging in their feeding habits and reproductive characters. Morphological scoring of presumed diagnostic characters and gene tic analysis of gene flow between the two forms by AFLP (amplified fragment length polymorphisms) will complement the data. To trace the order of speciation events that were or were not associated with host shifts in the European Oulema species, a phylogenetic analysis based on mtDNA sequences will be undertaken.