Beyond Simple Homology Searches: Multiple Sequence Alignments and Phylogenetic Trees

Abstract

Phylogenetic trees represent hypotheses about evolutionary relationships between organisms or nucleotide or amino acid sequences. Because the best BLAST hit often does not represent the most closely related sequence, phylogenetic analyses are an essential extension of inquiry into any new protein or gene. In this unit, the reader will first learn how to create a multiple sequence alignment using ClustalX. He or she will then learn how to use that alignment to build a neighbor-joining phylogeny using the program Geneious. Finally, the user will learn how to interpret the phylogeny in light of the research questions. Curr. Protoc. Essential Lab. Tech. 1:11.3.1-11.3.17. © 2009 by John Wiley & Sons, Inc.