Rather than making assumptions about which charactersare 'important', cladistics demands that the evolutionaryrelevanceofindividualcharactersbedefined(A)(B)WingsWingsNowings5toes5toesItoe
Rather than making assumptions about which characters are 'important', cladistics demands that the evolutionary relevance of individual characters be defined
Molecular data have three advantages compared withother types of phylogenetic informationWhenmolecular data are used, a single experiment can provideinformation on many different characters: in a DNA sequence, forexample, every nucleotide position is a character withfourcharacter states,A,C,G and T.Large molecular datasets cantherefore be generated relatively quicklyMolecular character states are unambiguous: A, C, G and T areeasily recognizable and one cannot be confused with another.Some morphological characters, such as those based on the shapeofastructure,canbeless easyto distinguishbecause of overlapsbetweendifferentcharacterstates.Molecular data are easily converted to numerical formand henceare amenable to mathematical and statistical analysis
Molecular data have three advantages compared with other types of phylogenetic information • When molecular data are used, a single experiment can provide information on many different characters: in a DNA sequence, for example, every nucleotide position is a character with four character states, A, C, G and T. Large molecular datasets can therefore be generated relatively quickly. • Molecular character states are unambiguous: A, C, G and T are easily recognizable and one cannot be confused with another. Some morphological characters, such as those based on the shape of a structure, can be less easy to distinguish because of overlaps between different character states. • Molecular data are easily converted to numerical form and hence are amenable to mathematical and statistical analysis
Other molecular data and othersequencesImmunological data Protein electrophoresisDNA-DNA hybridization data DNA markers such as RFLPs, SSLPs andSNPsGene order·Gene content
Other molecular data and other sequences • Immunological data • Protein electrophoresis • DNA-DNA hybridization data • DNA markers such as RFLPs, SSLPs and SNPs • Gene order • Gene content
Much more data are coming"454 Life Sciences Aiming for the$10,000 Human Genome Sequence454Sequencing
Much more data are coming • “454 Life Sciences — Aiming for the $10,000 Human Genome Sequence” • 454 Sequencing