BIOLOGY 1B Lecture Notes - Lecture 7: Phylogenomics, Rafflesia, Cladistics
12 Jun 2018
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Lecture 7: Cladistic Applications
• Molecular techniques
o Proteins
o DNA-DNA hybridization
▪ Combine two DNA of species; heat it; determine how closely related thye were based on
when they separate
▪ The more heat you need to separate, the stronger the bond, the more closely related
▪ The more closely related they are, the fewer mispariings in hybridization
o Genetic sequencing and DNA alignment
o Number of genes in an animal
• Phylogenomics: study of whole genomes
• Ex. Rafflesia
o The worlds largest flower- related to other flowers but lacks many morphological aspects of
flowers- no root no stem
▪ Parasites another plant
▪ Couldn’t tell what its related to without molecular data
• Phylogram- branch lengths are relative to amount of evolutionary change
Hyrax: the closest relative to elephants
o Polytomy needs to be resolved
o Closest in time
• Mapping characters on trees
o Morphological characters on a molecular phylogeny
▪ Loss and recovery of wings in stick insects
• Origin of clothing related to lice
• Parental care and vocalization in crocodilians
o Crocodiles look for their young with vocalization and take care of them
• Extant phylogenetic bracket
o Nest brooding and vocalization
o Phylogeny based on behavioral traits
o You can infer that ancestors also raised young and used vocalization by parsimony
▪ Unless you think it evolved twice and was not in dinosaur
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