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Title: Molecular evolutionary processes in ctenostome bryozoans
Author: Waeschenbach, A.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2004
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The phylogenetic relationships between species of the stoloniferan ctenostome bryozoan genus Bowerbankia were examined using DNA sequences for two mitochondrial genes, 12S rDNA and cytochrome c oxidase subunit I (COI). The resultant phylogeny based on COI sequences was shown to be confounded by nuclear mitochondrial sequences (Numts). Primers specific to mtDNA copies of COI were designed. 12S rDNA sequences with mutations in highly conserved regions, as determined by secondary structure folding, are also suspected to be Numts, however, 12S rDNA Numts and cytoplasmic mitochondrial sequences could not be separated by phyogenetic methods. Identical COI Numts were found in the carnosan Alcyonidium diaphanum and several Bowerbankia species, suggesting that transfer into the nucleus predates the divergence of the Stolonifera and Carnosa. One 12S rDNA haplotype common to Vesicularia spinosa, Amathia lendigera and bowerbankia spp. and two common to Bowerbankia spp. and Alcyonidium spp. were found. The occurrence of these identical haplotypes suggests that nuclear transfer of 12S rDNA might have occurred once within the Vesiculariidae and twice prior to the divergence of the Stolonifera and the Carnosa. Bryozoan sequences were obtained for the first time for the nuclear ribosomal multigene family 18S rDNA - ITS1 - 5.8S and species specific-primers for the ctenostome bryozoan Flustrellidra hispida were designed. Sequences from two populations, Millport (Scotland) and Mumbles (Wales) were obtained, with no significant genetic structure detected between the two populations nor within populations; however, ITS1 copies in the Mumbles population were slightly more homogenised than they were in the Millport population. Possible underlying processes leading to this difference are discussed. Furthermore, pseudogene copies could also be identified for 18S rDNA - ITS1 - 5.8S rDNA. In order to avoid amplification of contaminant DNA originating from cryptic organisms commonly present on the exterior and in the interior of bryozoans, such as ciliates, stramenopiles and fungi, a method using individually lysed larvae, previously used on Mytilus edulis (Sutherland et al 1998), was adapted for bryozoans.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available