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One way to visualize the similarity between two protein or nucleic acid sequences is to use a similarity matrix, known as a dot plot. These were introduced by Gibbs and McIntyre in 1970 [1] and are two-dimensional matrices that have the sequences of the proteins being compared along the vertical and horizontal axes.
This list of phylogenetics software is a compilation of computational phylogenetics software used to produce phylogenetic trees. Such tools are commonly used in comparative genomics , cladistics , and bioinformatics .
Phylogenetic trees generated by computational phylogenetics can be either rooted or unrooted depending on the input data and the algorithm used. A rooted tree is a directed graph that explicitly identifies a most recent common ancestor (MRCA), [citation needed] usually an inputed sequence that is not represented in the input.
Here two different gap penalties are applied for opening a gap and for extending a gap. Typically the former is much larger than the latter, e.g. -10 for gap open and -2 for gap extension. This results in fewer gaps in an alignment and residues and gaps are kept together, traits more representative of biological sequences.
A phylogenetic network is any graph used to visualize evolutionary relationships (either abstractly or explicitly) [1] between nucleotide sequences, genes, chromosomes, genomes, or species. [2] They are employed when reticulation events such as hybridization, horizontal gene transfer, recombination, or gene duplication and loss are believed to ...
Care should also be taken to avoid situations in which the species from which the sequences were taken are distantly related, but the gene encoded by the sequences is highly conserved across lineages. Horizontal gene transfer, especially between otherwise divergent bacteria, can also confound outgroup usage.
For a clustering example, suppose that five taxa (to ) have been clustered by UPGMA based on a matrix of genetic distances.The hierarchical clustering dendrogram would show a column of five nodes representing the initial data (here individual taxa), and the remaining nodes represent the clusters to which the data belong, with the arrows representing the distance (dissimilarity).
Bottom: in a separate species, an unrelated gene has a similar function (Gene C) but has a separate evolutionary origin and so is an analog. Homologous sequences are orthologous if they are inferred to be descended from the same ancestral sequence separated by a speciation event: when a species diverges into two separate species, the copies of ...