Differential gene expression during early development in recently evolved and sympatric Arctic charr morphs

PeerJ

article

Jóhannes Guðbrandsson¹  Sigríður Rut Franzdóttir¹  Bjarni Kristófer Kristjánsson⁴  Ehsan Pashay Ahi¹  Valerie Helene Maier¹  Kalina Hristova Kapralova¹  Sigurður Sveinn Snorrason¹  Zophonías Oddur Jónsson¹  Arnar Pálsson¹ 

[1] Institute of Life and Environmental Sciences, University of Iceland;Freshwater Division, Marine and Freshwater Research Institute;Biomedical Center, University of Iceland;Hólar University College;Karl-Franzens-Universität

关键词: Divergence;    Salmonid;    Transcriptome;    Evolution;    Lake Thingvallavatn;    Salvelinus alpinus;    3′-bias;    RNA sequencing;   

DOI  :  10.7717/peerj.4345

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Phenotypic differences between closely related taxa or populations can arise through genetic variation or be environmentally induced, leading to altered transcription of genes during development. Comparative developmental studies of closely related species or variable populations within species can help to elucidate the molecular mechanisms related to evolutionary divergence and speciation. Studies of Arctic charr (Salvelinus alpinus) and related salmonids have revealed considerable phenotypic variation among populations and in Arctic charr many cases of extensive variation within lakes (resource polymorphism) have been recorded. One example is the four Arctic charr morphs in the ∼10,000 year old Lake Thingvallavatn, which differ in numerous morphological and life history traits. We set out to investigate the molecular and developmental roots of this polymorphism by studying gene expression in embryos of three of the morphs reared in a common garden set-up. We performed RNA-sequencing, de-novo transcriptome assembly and compared gene expression among morphs during an important timeframe in early development, i.e., preceding the formation of key trophic structures. Expectedly, developmental time was the predominant explanatory variable. As the data were affected by some form of RNA-degradation even though all samples passed quality control testing, an estimate of 3′-bias was the second most common explanatory variable. Importantly, morph, both as an independent variable and as interaction with developmental time, affected the expression of numerous transcripts. Transcripts with morph effect, separated the three morphs at the expression level, with the two benthic morphs being more similar. However, Gene Ontology analyses did not reveal clear functional enrichment of transcripts between groups. Verification via qPCR confirmed differential expression of several genes between the morphs, including regulatory genes such as AT-Rich Interaction Domain 4A (arid4a) and translin (tsn). The data are consistent with a scenario where genetic divergence has contributed to differential expression of multiple genes and systems during early development of these sympatric Arctic charr morphs.

【 授权许可】

CC BY