Words similar to presence-absence
Example sentences for: presence-absence
How can you use “presence-absence” in a sentence? Here are some example sentences to help you improve your vocabulary:
Here, we compare the topologies produced with five, largely independent approaches to genome-tree building: i) presence-absence of genomes in Clusters of Orthologous Groups of proteins (COGs); ii) conservation of local gene order (pairs of adjacent genes) among prokaryotic genomes; iii) distribution of percent identity between apparent orthologs; iv) sequence conservation in concatenated alignments of ribosomal proteins; v) comparative analysis of multiple trees reconstructed for representative protein families.
Probably the most obvious of such characteristics is the presence-absence of representatives of the analyzed species in orthologous groups of genes, and recently, at least three groups have employed this approach to build genome trees, primarily for prokaryotes [ 8 9 10 ] . An alternative way to construct a genome tree involves using the mean or median level of similarity among all detectable pairs of orthologs as the measure of the evolutionary distance between species [ 11 ] . Yet another possibility involves building species trees by comparing gene orders.
We find that, while the presence-absence approach is most heavily affected by gene loss and horizontal transfer, the other four methods reveal stronger phylogenetic signals.
That these bacteria do not group with the parasites despite similar genome sizes, suggests that it is not the number of genes per se, but rather the degree of genome degradation and the loss of coherent sets of genes that affect the topology of the presence-absence tree.
The topology of the tree based on gene pair conservation seems to carry a stronger phylogenetic signal than the gene presence-absence tree because it correctly groups together related free-living and parasitic bacteria despite major differences in gene repertoires (Fig.
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