BIOL 102 Lecture Notes - Lecture 8: Phylogenetic Tree, Extinction Event, Adaptive Radiation
Document Summary
History of life on earth and the organization/classification of life. Common ancestry is not the only reason that two species might appear similar. Organisms that are not closely related evolve similar adaptation as a result of independent episodes of natural selection. Analogous structures- structure have very different genetic origins, however they share similar functions. In parallel evolution, related species are physically separated bust still evolve similar feature in their different locations. 4. 5 billion years ago- origin of earth. 2. 5 billion years ago- oxygen accumulates (photosynthesis) 2. 1 billion years ago- eukaryotes- first nucleated cells (single-celled) 1. 2 billion years ago- first multi-celled eukaryotes. 5 billion years ago-cambrian explosion of multicellular life. Before the first cells could evolve, several fundamental conditions were required: essential elements: to compose organic molecules, continual source of energy: mainly nuclear fusion reactions within the sun, temperature range permitting liquid water: otherwise metabolic reactions cease. 3. 5 billion years ago left no easily discernible evidence.
