Abstract
A multidisciplinary approach was adopted in the investigation of diversity in the widespread Asian pitviper genus Ovophis. Combined morphological and mitochondrial DNA based phylogenetic analysis was used to infer relationships within the group, and investigation of diversity in the venom toxin phospholipase A2 genes was carried out utilizing the mitochondrial phylogenetic tree. Preliminary work involving a second pitviper genus, Viridovipera, demonstrated the efficacy of mtDNA phylogenetic methods in uncovering relationships in Asian pitviper species, and broad agreement with hemipenial morphology underlines the effectiveness of a multidisciplinary approach. In Ovophis, two independent Bayesian phylogenetic inference methods returned similar well resolved trees. The divisions revealed in the tree agree only partly with current species and subspecies divisions. Morphological data were found to be in broad agreement with the phylogenetic tree. The previously defined subspecies Ovophis monticola orientalis and Ovophis montico/a makazayazaya were not supported as subspecies of Ovophis monticola in the phylogenetic analysis, instead showing closer affinity with Ovophis tonkinensis. The subspecies Ovophis monticola zhaokentangi was also unsupported in the tree and the morphological analysis. Relationships within the type species clade were
more complex than previously considered, and a potential new species was
uncovered in Northern Viet Nam. A substantially revised taxonomy of Ovophis
was proposed to take account of these newly revealed relationships, and regions in which further work needs to be concentrated for clarification of remaining taxonomic issues were identified. The venom of Ovophis was found to contain several distinct PLA2 proteins, and a number of nuclear gene copies were sequenced belonging to an estimated three or more independent gene lineages stemming from duplication events. Evidence of positive selection was found in the patterns of substitution within the genes, and inconsistencies between trees based on intron and exon partitions suggest adaptive constraint or convergence in strongly expressed proteins.
| Date of Award | Sept 2009 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Sponsors | Natural Environment Research Council (NERC) & Anne Vernon Travel Fund |
| Supervisor | Anita Malhotra (Supervisor) & Roger Thorpe (Supervisor) |
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