BIOC50H3 Lecture Notes - Lecture 3: Sigillaria, Coleochaetales, Charales
23 Oct 2015
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Document Summary
Web of life hypothesis common ancestor was not a single species but instead a community of species that readily traded trees. Ring of life hypothesis a fusion that eventually separates over time (storage = archeans; metabolism = bacteria) Problem bacteria are not able to go through phagocytosis = unlikely. Chronocyte hypothesis a hypothetical lineage evolved proto-eukaryote; when it evolves to an archean it becomes a proper eukaryote (evolves a cytoskeleton and phagocytosis) Mitochondria and chloroplast both come from different lineages of bacteria that were once free living organisms (mutual integration) Billion years after origin eukaryotes were unicellular and most still are. Multicellularity evolved independently in animals, fungi and plants. Due to the advantage of dividing labor between different cell types. Multicellular bacteria as old as 2100 myr possible. Fauna dates from 570-542 mya, just prior to start of cambrian. Simple body plans - mostly asymmetrical or with radial symmetry (bilateral becomes common in cambrian)
