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Title: Hox3 duplication and divergence in the Lepidoptera
Author: Livraghi, Luca
ISNI:       0000 0004 7430 8235
Awarding Body: Oxford Brookes University
Current Institution: Oxford Brookes University
Date of Award: 2017
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Using the Speckled Wood Butterfly Pararge aegeria as the model species, this thesis presents the possible evolutionary significance of a set of duplications found in the Hox cluster of the Lepidoptera, called the Special Homeobox genes. An annotation of this duplicated cluster across a wide number of Lepidoptera was performed in order to assess patterns of duplication and loss across the order. The sequences recovered revealed a large amount of variation associated with the duplicate genes, indicating these are evolving very rapidly in different lineages. Patterns of sequence variation were examined to ascertain whether the observed variation was maintained due to selection at three separate levels of divergence: within the Ditrysia, within the more recently diverged Heliconius genus, and at the intraspecific level by quantifying nucleotide polymorphism within Pararge aegeria. Selective pressures were found to be operating between paralogous and orthologous genes, suggesting these have evolved, in part, under positive selection. The potential function of the duplicates was examined by means of CRISPR/Cas9 geneome editing, but revealed inconclusive results. Genome editing, however, was shown to be largely applicable to P. aegeria, and resulted in consistent mutations associated with wing patterning genes. The potential significance of the duplications for Lepidopeteran biology are discussed, as well as future applications for genome editing techniques in P. aegeria.
Supervisor: Breuker, Casper ; Gibbs, Melanie ; Holland, Peter Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral