Siu Ting Salvatierra, Karen (2014) Novel approaches for large-scale phylogenetics and applications in the context of the amphibian tree of life. PhD thesis, National University of Ireland Maynooth.
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Abstract
During this thesis, I addressed some problems associated with large-scale
phylogenetic analyses by tackling issues related to missing data and careful
handling and addition of novel data in large-scale reconstructions, presenting an
application of this approach in the context of amphibian phylogenetics.
I developed a method (called “Concatabominations”) building on the original Safe
Taxonomic Reduction method (Wilkinson 1995) as an alternative approach to the
issue of identifying rogue taxa. The safe removal of rogue taxa due to missing data
can potentially reduce the terraces in tree space search and improve resolution in
the final consensus tree. In a pragmatic point of view, the new method can help in
targeting taxa that require further sampling during a research design.
Novel sequence data for the rediscovered Ericabatrachus baleensis allowed to explore
its placement in the Amphibian tree of life. I tested the inclusion of novel data using
a backbone alignment from a previous work (de novo analysis) and a backbone
phylogenetic tree (constrained analysis), after careful curation of gene partitions to
include in an analysis. I found that the use of a constrained phylogenetic inference
using a previous accepted tree seems to be a practical solution to the rapid
phylogenetic placement of a taxon in cases of well-supported relationships.
However, a de novo analysis might ensure an optimal alignment and avoid risks
introduced when adding new data.
Finally, I investigated the evolutionary relationships of the three lineages of the
extant amphibians (Anura, Caudata and Gymnophiona) using an independent
source of evidence: miRNAs, recently used to help resolve difficult phylogenetic
problems. The analyses yielded a high number of shared miRNAs using the
Xenopus tropicalis genome, contrasting with a lower number of miRNAs discovered
using the Axolotl transcriptome. This suggests that not using genomic data is not
ideal to validate miRNAs. Nevertheless, in spite of the limitations, I was able to
find two potential novel miRNAs: one supporting the monophyly of Lissamphibia,
and another supporting the Batrachia hypothesis.
Overall, I hope the work developed in this thesis contributes with new insights into
large-scale phylogenetics and in particular to amphibian phylogenetics.
Item Type: | Thesis (PhD) |
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Keywords: | large-scale phylogenetics; amphibian tree of life; |
Academic Unit: | Faculty of Science and Engineering > Biology |
Item ID: | 5399 |
Depositing User: | IR eTheses |
Date Deposited: | 16 Sep 2014 11:12 |
Funders: | IRCSET |
URI: | https://mural.maynoothuniversity.ie/id/eprint/5399 |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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