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A Practical Guide to Phylogenetics for Nonexperts
Published on: February 6, 2014
Investigating phylogenetic relationships within the Apicomplexa using sequence data: the search for homology
1Department of Pathobiology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada. jbarta@uoguelph.ca
Methods (San Diego, Calif.)
|February 12, 1998
Summary
Accurate molecular evolutionary studies rely on precise sequence alignment. Utilizing hypervariable regions of 18S ribosomal RNA (rRNA) gene sequences improves evolutionary hypotheses for closely related taxa.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Bioinformatics
Background:
- Molecular studies inferring homology and relatedness are evolutionary.
- Reliable evolutionary hypotheses from molecular sequences depend on accurate sequence alignment.
- Positional homology is crucial for aligning bases/amino acids in the same gene position.
Purpose of the Study:
- To evaluate methods for reliable molecular sequence alignment in evolutionary studies.
- To identify optimal gene targets and taxa for unambiguous sequence alignment.
- To enhance the accuracy of evolutionary hypotheses derived from molecular data.
Main Methods:
- Comparing mathematically derived alignments with those based on conserved secondary structures and compensatory base changes.
- Employing staggered sequence alignments in hypervariable regions of 18S small subunit ribosomal RNA (rRNA) gene sequences.
- Independently aligning subsets of taxa within hypervariable regions.
Main Results:
- Alignments based on conserved secondary structures are more reliable than those based solely on local sequence similarity.
- Staggered alignments in hypervariable regions allow inclusion of more primary sequence data.
- This increases the information content of the dataset for phylogenetic analysis.
Conclusions:
- Conserved secondary structure analysis is superior to local similarity for reliable molecular alignments.
- Hypervariable regions of 18S rRNA gene sequences are critical for resolving relationships among closely related taxa.
- Improved alignment strategies enhance the accuracy of evolutionary inferences in molecular studies.
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