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The Major Lineages of Life Molecular data challenges 5 Kingdoms Monera was too diverse 2 distinct lineages of prokaryotes Protists are still too diverse not yet sorted out Chapter 26 Phylogeny and the Tree of Life • Phylogeny is the evolutionary history of a species or group of related species • The discipline of systematics classifies organisms and determines their evolutionary relationships • Systematists use fossil, molecular, and genetic data to infer evolutionary relationships • Taxonomy is the ordered division and naming of organisms 3 Domain system • Domains = “Super” Kingdoms – Bacteria – Archaea • extremophiles = live in extreme environments – methanogens – halogens – thermophiles – Eukarya • eukaryotes – – – – protists fungi plants animals Classification Eukaryote • Old 5 Kingdom system Prokaryote • Monera, Protists, Plants, Fungi, Animals • New 3 Domain system – reflects a greater understanding of evolution & molecular evidence • Prokaryote: Bacteria • Prokaryote: Archaebacteria • Eukaryotes – Protists – Plants – Fungi – Animals Archaebacteria & Bacteria Kingdom Bacteria Kingdom Archaebacteria Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia Fungi Kingdoms absorptive nutrition Animalia ingestive nutrition Plantae autotrophs Protista uni- to multicellular Eubacteria multicellular Archaebacteria prokaryotes Single-celled ancestor eukaryotes heterotrophs Finding commonality in variety • Organisms classified from most general group, domain, down to most specific, species – domain, kingdom, phylum, class, order, family, genus, species use the mnemonic! The Evolutionary Perspective Phylogenies are inferred from morphological and molecular data • To infer phylogenies, systematists gather information about morphologies, genes, and biochemistry of living organisms • Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with different structures or sequences Cladistics • Cladistics groups organisms by common descent • A clade is a group of species that includes an ancestral species and all its descendants • Clades can be nested in larger clades, but not all groupings of organisms qualify as clades
