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Jessica Hawthorn

BIO211 Sept 26 th Evolution and Evolutionary Relationships Scientific Method Rules: 1. can only invoke natural processes 2. observations/hypotheses must be testable 3. results must be reproducible 4. observations/tests must be potentially falsifiable Theory vs. Truth - theories are either corroborated or falsified o always subject to future tests and revision - theories have not yet been falsified: o theory of universal gravitation o theory of special relativity o theory of natural selection What is evolution? - changes in heritable traits in populations (groups of individuals of the same species that live together) over time - can result in new species The Tree of Life - relationships between organisms can be represented by a single branching tree - all extinct and extant species can be traced back to a single common ancestor Taxonomic Groups - taxonomy: - taxonomic groups: o the 6 kingdoms and their subordinate groups o taxon: unranked term for “group” (plural=taxa) o traditionally:  kingdom > phylum > class > order > family > genus > species - Carolus Linnaeus o not a “tree-thinker” o thought similarities among species reflect rational, orderly plan of creation o developed classification of all species into higher level taxa (taxonomy) to reflect plan of creation - species: o name includes genus o biological species concept: group of individuals that can interbreed and produce fertile offspring  cannot be tested for extinct species o morphological species concept: - Jean-Baptiste Pierre Antoine de Monet, Chevalier de la Marck: o transformation via inheritance of acquired traits: characteristics acquired during the life of ancestor passed on to descendants Charles Darwin - set sail on HMS Beagle in 1831 - keen observer, hired as ship’s naturalist - uniformitarianist - similarities between extinct (fossil) and extant (living) animals in South America - South American rhea similar to African ostrich - Galapagos tortoises: o different shell shapes and neck lengths on each island  correspond to different vegetation heights - Galapagos finches: o similar to South American mainland finches o different beak types - additional observations after the Beagle voyage: o embryology: embryos of many vertebrates similar for most of development o selective breeding of domestic animals o homology: presence of anatomical structures in two different groups of organisms that have the same ancestral origin, but now serve different functions o vestigial organs: anatomical structures that serve no apparent purpose but resemble structures that perform functions in other organisms o adaptation: specialized feature of an organism that has evolved to function in a particular way of life Natural Selection 1. variation of heritable traits occurs within populations 2. some traits provide advantages over others in competition for resources 3. in each generation, more offspring are produced than can survive 4. individuals with advantageous traits survive to bear offspring with same trai
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