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Phylogenetics and the Tree of Life. Level 1 Biological Diversity Jim Provan. Campbell: Chapters 25 & 26. Key events in the evolution of life. The major lineages of life. Linnaeus originally divided all known forms of life between animal and plant kingdoms
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Phylogenetics and the Tree of Life Level 1 Biological Diversity Jim Provan Campbell: Chapters 25 & 26
The major lineages of life • Linnaeusoriginally divided all known forms of life betweenanimalandplantkingdoms • The discovery of bacteria did not change this: • Bacteriaclassed with plants • Fungiclassed with plants • Unicellular creatures: • Ingest food: animals (protozoa) • Photosynthetic: plants
Taxonomy employs a hierarchical system of classification • Developed by Linnaeus • Has two main features: • Binomial(latin name) unique to each species • First word isgenus; second word isspecific epithet • Each genus can include many related species • Defines organism and removes ambiguity • A hierarchical “filing system”: • Begins with binomial nomenclature • Progresses upwards, becoming more inclusive • Range oftaxonomic levels
Domain Eukarya Hierarchical classification
Determining monophyletic taxa • In order to truly reflect evolutionary history, all taxonomic levels should bemonophyletic • Not always the case: • Kingdom Plantae ispolyphyletic • Class Reptilia isparaphyletic, since it does not include Aves
Discriminating between homology and analogy • Homology: likeness due to shared ancestry • Analogy: likeness due toconvergent evolution: • Forelimbs of mammals are homologous • Wings of birds and bats are analogous since they originated independently from forelimbs of different ancestors
The traditional five-kingdom system • Proposed byRobert Whittakerin 1969 • Recognises prokaryotesand eukaryotes • All prokaryotes placed in KingdomMonera • Recognises three kingdoms of multicellular eukaryotes • Protistsare largely unicellular eukaryotes
Plantae Fungi Animalia Domain Bacteria Domain Archaea Plantae Fungi Animalia Alternative classification systems Monera Protista Plantae Fungi Animalia Bacteria Archaea Protista Archaezoa Chromista Domain Eukarya (Eukaryotes) Euglenozoa Alveolata Archaezoa Stramenopila Rhodophya
Bacteria Archaea Eukarya Animals Plants Plants - where do they (and we) fit in? Fungi