Chapter 19Molecular Phylogenetics
Chapter 19 Molecular Phylogenetics
. If genomes evolve by the gradual accumulation ofmutations, then the amount of difference in nucleotidesequence between a pair of genomes should indicatehow recently those two genomes shared a commonancestor. Two genomes that diverged in the recent pastwould be expected to have fewer differences than a pairof genomes whose common ancestor is more ancient.This means that by comparing three or more genomes itshould be possible to work out the evolutionaryrelationships between them.These are the objectives of molecular phylogenetics, orupdated as phylogenomics, on which you can findseveral important reviews published in the past year
• If genomes evolve by the gradual accumulation of mutations, then the amount of difference in nucleotide sequence between a pair of genomes should indicate how recently those two genomes shared a common ancestor. Two genomes that diverged in the recent past would be expected to have fewer differences than a pair of genomes whose common ancestor is more ancient. This means that by comparing three or more genomes it should be possible to work out the evolutionary relationships between them. • These are the objectives of molecular phylogenetics, or updated as phylogenomics, on which you can find several important reviews published in the past year
19.1 From classification tomolecular phylogenetics. Linnaeus was a systematicist not anevolutionist, his objective being to place allknown organisms into a logicalclassification.: Phylogeny indicates not just thesimilarities between species but also theirevolutionary relationships. Morphological>molecular—>Genomics· Phylogenetics>phylogenomics
19.1 From classification to molecular phylogenetics • Linnaeus was a systematicist not an evolutionist, his objective being to place all known organisms into a logical classification. • Phylogeny indicates not just the similarities between species but also their evolutionary relationships. • Morphological—>molecular—>Genomics • Phylogenetics—>phylogenomics
19.1.1 The Origins of MolecularPhylogeneticsTIMEModernspeciesAncestor
19.1.1 The Origins of Molecular Phylogenetics
Phenetics（数值分类或表征分类）andcladistics（支序分类或分支系统学）: Pheneticists argued that classificationsshould encompass as many variablecharacters as possible, these charactersbeing scored numerically and analyzed byrigorous mathematical methods. Cladistics also emphasizes the need forlarge datasets but differs from phenetics inthat it does not give equal weight to allcharacters
Phenetics (数值分类或表征分类) and cladistics (支序分类或分支系统学) • Pheneticists argued that classifications should encompass as many variable characters as possible, these characters being scored numerically and analyzed by rigorous mathematical methods. • Cladistics also emphasizes the need for large datasets but differs from phenetics in that it does not give equal weight to all characters