Applied Science, Life Science, Biology
Material Type:
Community College / Lower Division, College / Upper Division
Rice University
Analogous Trait, Analogy, Basal Taxon, Binomial Nomenclature, Branch Point, CLASS, Carl Linnaeus, Clade, Cladistic Method, Cladistics, Classification Levels, Classification System, Domain, Eukaryote Evolution, Eukaryote HGT, Eukaryote-first Hypothesis, Evolution, Evolutionary Relationships, Family, GTA, Gene Transfer Agent, Genome Fusion, Genus, HGT, Homologous Trait, Homoplasy, Horizontal Gene Transfer, James Lake, Kingdom, Lateral Gene Transfer, Linnaean System, Maximum Parsimony, Mitochondria-first Hypothesis, Molecular Comparison, Molecular Systematics, Network Model, Order, Phylogenetic Model, Phylogenetic Tree, Phylogeny, Phylum, Polytomy, Prokaryote HGT, Prokaryote-first Hypothesis, Ring Model, Ring of Life, Rooted, Shared Ancestral Character, Shared Characteristic, Shared Derived Character, Sister Taxa, Species, Systematics, Taxon, Taxonomy, Tree of Life, Web Model, Web of Life
Creative Commons Attribution-NonCommercial 4.0


Section 1

 Photo shows a bee collecting nectar from a flower.
The life of a bee is very different from the life of a flower, but the two organisms are related. Both are members the domain Eukarya and have cells containing many similar organelles, genes, and proteins. (credit: modification of work by John Beetham)

This bee and Echinacea flower (Figure) could not look more different, yet they are related, as are all living organisms on Earth. By following pathways of similarities and changes—both visible and genetic—scientists seek to map the evolutionary past of how life developed from single-celled organisms to the tremendous collection of creatures that have germinated, crawled, floated, swam, flown, and walked on this planet.