One genome, two sexes: genomic and transcriptomic bases of sexual dimorphism in species without sexual chromosomes

Rago, Alfredo (2017). One genome, two sexes: genomic and transcriptomic bases of sexual dimorphism in species without sexual chromosomes. University of Birmingham. Ph.D.

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Abstract

Sex in the jewel wasp Nasonia vitripennis is determined by whether eggs are haploid or diploid: the radically different male and female phenotypes share the same genome, showing that their sexual dimorphism is not genetic but rather a specific case of phenotypic plasticity. As a consequence, all of Nasonia’s genes are selected for both male and female fitness. The impact of this diverging selective pressure on the evolution of its genome and whether it is comparable to organisms with sex chromosomes are questions still largely unanswered.
In this thesis, I develop and apply a set of tools for the integrative analysis of different aspects of Nasonia’s biology. I characterize the improved gene set of Nasonia and identify several lineage-specific gene family expansions. I provide an algorithm for detection and comparison of splicing and transcription signal from transcriptomic data in non-model organisms. Finally, I identify the different regulatory processes that enable generation of disparate phenotypes using network analyses on Nasonia’s developmental transcriptome.
Nasonia’s transcriptome shows high amounts of sex-bias not tied to linkage groups or alternative splicing. Early development shows a prevalence of sex-biased interactions between transcripts rather than single-gene upregulation, and sex-biased networks are enriched in lineage-specific regulators.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):