Читать книгу Principles of Microbial Diversity - James W. Brown - Страница 49

The raw material used by a phylogenetic tree-generating program is an alignment (Fig. 3.6). A sequence alignment is a two-dimensional matrix of multiple sequences. Each sequence is in a line (row) of the matrix. Each position (column) in an alignment contains homologous (corresponding) residues of each sequence. Gaps (usually shown as dashes) are added where needed to maintain the alignment; these gaps represent the absence of bases in the sequence that are present in some other sequence(s) in the alignment.