The darwinian view of life

The Darwinian View of Life
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Unformatted text preview: 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? 1800s 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 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 didnt 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! 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 ...
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