The Darwinian View of Life - The Darwinian View of Life:...

The Darwinian View of Life
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The Darwinian View of Life: Patterns and Process in Nature  16:02 Patterns in Nature Organisms seem to “fit: their environments  Groups nested within groups  o Why? 1800’s – a revolutionary break through: EVOLUTION!  Species change!  o No longer fixed, unchangeable types (since Plato)  Species are related by shared ancestry!  o “Descent with modification” (family tree)  o Explains why we see nested groups!  Populations evolve by natural selection (at least mostly)  o Process explains how species have come to “fit: their environment  Who had the “AHAAA!”’s ?  Lamarck (~1810)  o First to propose theory of evolution (=species change)  Charles Darwin and Alfred Russell Wallace (~1850)  o Co-discovered descent with modification and natural selection  o Read Box 24.1 “Why Darwin gets most of the credit”  A Revolutionary Breakthrough!  Mechanism for change through time 
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Variation within a species is key! (No noise)  Population thinking (not typological thinking)  o Population- look at each individual, individuality is important  o Typological- all the same type  What is Evolution?  Evolution occurs when there is a change in genetic characteristics of a  population over time (ex. A change in Allele frequency)  Theory of evolution: all organisms on Earth are related by common ancestry  and have changed overtime, largely via natural selection  Evolutionary Process  Selection effected by humans (“artificial selection”) provides many familiar  examples  Selection- anyone can do it!  Figure 13  Each individual didn’t change through time, but because individuals had  different reproductive output, the population change  Population can evolve  o Phyletic evolution- evolution with in a lineage, without splitting  Populations that evolve can also split into 2 (or more) genetically different  populations  o Specification: the splitting of one species into 2 (or more) species  Adaptations  Natural selection leads to adaptations  o Adaptations: a trait that increases the fitness of an individual in a particular  environment  o Fitness: the ability of an individual to produce offspring  o But not all useful features are adaptations for that use! 
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Adaptations vs. Good fit  Not all useful features are adaptations for that use  Figure 1.9 (Giraffes); neck not for food but to establish dominance over mate  aka huge sledge hammer  Taxonomy  Taxonomy naming and classification of organisms  Linnaeus (1730s)- botanist Figure 1.5 (memorize)  o “Linnaean taxonomy”  The Tree of Life: groups within groups  Phylogenetic tree 
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