The tremendous diversity of Hymenoptera is commonly attributed to the evolution of parasitoidism in the last common ancestor of parasitoid sawflies (Orussidae) and wasp-waisted Hymenoptera (Apocrita). However, Apocrita and Orussidae differ dramatically in their species richness, indicating that the diversification of Apocrita was promoted by additional traits. These traits have remained elusive due to a paucity of sawfly genome sequences, in particular those of parasitoid sawflies. Here we present comparative analyses of draft genomes of the primarily phytophagous sawfly Athalia rosae and the parasitoid sawfly Orussus abietinus. Our analyses revealed that the ancestral hymenopteran genome exhibited traits that were previously considered unique to eusocial Apocrita (e.g., low transposable element content and activity) and a wider gene repertoire than previously thought (e.g., genes for CO2 detection). Moreover, we discovered that Apocrita evolved a significantly larger array of odorant receptors than sawflies, which could be relevant to the remarkable diversification of Apocrita by enabling efficient detection and reliable identification of hosts.

中文翻译：

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锯蝇基因组揭示了进化习性，促进了寄生性寄生虫和真人膜翅目的巨大辐射。

膜翅目动物的巨大多样性通常归因于在寄生寄生的锯齿蝇（Orussidae）和黄蜂腰膜翅目昆虫（Apocrita）的最后共同祖先中的类寄生虫进化。但是，Apocrita和Orussidae的物种丰富度差异很大，这表明Apocrita的多样化是由其他性状促进的。由于很少的锯蝇基因组序列，特别是寄生虫锯齿的基因组序列，这些特性仍然难以捉摸。在这里，我们介绍了主要是植物吞噬性锯蝇Athalia rosae和寄生虫锯蝇Orussus abietinus的基因组草案的比较分析。我们的分析表明，祖先膜翅目基因组表现出以前被认为是真社会Apocrita所特有的特征（例如，低的转座因子含量和活性）和比以前认为的更广泛的基因库（例如，用于CO2检测的基因）。此外，我们发现Apocrita进化了比锯齿形更大的气味受体阵列，这可能与Apocrita的显着多样化有关，因为它能够有效检测和可靠鉴定宿主。