Ferreira Pedro G, Patalano Solenn, Chauhan Ritika, Ffrench-Constant Richard, Gabaldón Toni, Guigó Roderic, Sumner Seirian
Genome Biol. 2013 Feb 26;14(2):R20. doi: 10.1186/gb-2013-14-2-r20.
Understanding how alternative phenotypes arise from the same genome is a major challenge in modern biology. Eusociality in insects requires the evolution of two alternative phenotypes - workers, who sacrifice personal reproduction, and queens, who realize that reproduction. Extensive work on honeybees and ants has revealed the molecular basis of derived queen and worker phenotypes in highly eusocial lineages, but we lack equivalent deep-level analyses of wasps and of primitively eusocial species, the latter of which can reveal how phenotypic decoupling first occurs in the early stages of eusocial evolution.
We sequenced 20 Gbp of transcriptomes derived from brains of different behavioral castes of the primitively eusocial tropical paper wasp Polistes canadensis. Surprisingly, 75% of the 2,442 genes differentially expressed between phenotypes were novel, having no significant homology with described sequences. Moreover, 90% of these novel genes were significantly upregulated in workers relative to queens. Differential expression of novel genes in the early stages of sociality may be important in facilitating the evolution of worker behavioral complexity in eusocial evolution. We also found surprisingly low correlation in the identity and direction of expression of differentially expressed genes across similar phenotypes in different social lineages, supporting the idea that social evolution in different lineages requires substantial de novo rewiring of molecular pathways.
These genomic resources for aculeate wasps and first transcriptome-wide insights into the origin of castes bring us closer to a more general understanding of eusocial evolution and how phenotypic diversity arises from the same genome.
理解相同基因组如何产生不同表型是现代生物学面临的一项重大挑战。昆虫的群居性需要两种不同表型的进化——放弃个体繁殖的工蜂，以及实现繁殖的蜂后。对蜜蜂和蚂蚁的大量研究揭示了高度群居谱系中衍生的蜂后和工蜂表型的分子基础，但我们缺乏对黄蜂和原始群居物种的同等深度分析，而后者可以揭示表型解耦在群居进化早期是如何首次发生的。
我们对原始群居的热带胡蜂加拿大黄胡蜂不同行为型的大脑转录组进行了20 Gbp的测序。令人惊讶的是，在表型之间差异表达的2442个基因中，75%是新基因，与已描述序列没有显著同源性。此外，相对于蜂后，这些新基因中有90%在工蜂中显著上调。新基因在群居早期的差异表达可能对促进群居进化中工蜂行为复杂性的进化很重要。我们还发现，在不同社会谱系中，相似表型间差异表达基因的同一性和表达方向的相关性出奇地低，这支持了不同谱系中的社会进化需要分子途径大量重新布线的观点。
这些针对针尾部黄蜂的基因组资源以及对不同型起源的首次全转录组洞察，使我们更接近对群居进化以及相同基因组如何产生表型多样性的更全面理解。
