Lecture_7_phylogenetics

Unfortunately it is impossible to ever conclusively

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: be quan?fied. •  Given a set of gene sequences, it should be possible to reconstruct the evolu?onary rela?onships among genes and among organisms. Disclaimers •  This area of computa?onal biology is an intellectual minefield! •  Neither the theory nor the prac?cal applica?ons of any algorithms are universally accepted throughout the scien?fic community •  The applica?on of different sokware packages to a data set is very likely to give different answers Types of Trees A natural model to consider is that of rooted trees Orthologs vs. Paralogs •  When comparing gene sequences, it is important to dis?nguish between iden?cal vs. merely similar genes in different organisms. •  Orthologs are homologous genes in different species with analogous func?ons. •  Paralogs are similar genes that are the result of a gene duplica?on. –  A phylogeny that includes both orthologs and paralogs is likely to be incorrect. –  Some?mes phylogene?c analysis is the best way to determine if a new gene is an ortholog or paralog to other known genes. Are there “Correct Trees”? •  Despite all of these caveats, it is actually quite simple to use computer programs calculate phylogene?c trees for data sets. •  Provided the data are clean, outgroups are correctly specified, appropriate algorithms are chosen, no assu...
View Full Document

Ask a homework question - tutors are online