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Natural Variation & Artificial Selection

Natural Variation & Artificial Selection. Natural Variation & Artifical Selection. Darwin, through many observations, explained evolution by natural variation In 1859, Darwin published “On the Origin of Species” where he proposed his theory of evolution

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Natural Variation & Artificial Selection

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  1. Natural Variation & Artificial Selection

  2. Natural Variation & Artifical Selection • Darwin, through many observations, explained evolution by natural variation • In 1859, Darwin published “On the Origin of Species” where he proposed his theory of evolution • Natural variation – differences among individuals of a species and is found in all types of organisms (inherited traits) • Breeders routinely used variations to improve crops and livestock = selective breeding aka artificial selection • Artificial selection – nature provided the variation among different organisms, and humans selected those variations they found useful • Ex. Only cows that produce the most milk are bred

  3. Evolution by Natural Selection • Struggle for existence – members of each species compete regularly to obtain food, living space, and other necessities

  4. Evolution by Natural Selection (continued) • Survival of the fittest – how well suited an organism is to its environment • Fitness – ability of an individual to survive and reproduce in its specific environment • Adaptation – leads to fitness – any inherited characteristic that increases an organism’s chance of survival – can be physical or behavioral adaptations

  5. Survival of the Fittest (continued) • Generation after generation, individuals compete to survive and produce offspring • Individuals with characteristics that are NOT well suited to their environment die or leave few offspring • Individuals with characteristics that ARE well suited to their environment survive and reproduce most successfully

  6. Natural Selection • Takes place without human control or direction • Over time, natural selection results in changes in the inherited characteristics of a population

  7. Descent with Modification • Over long periods of time, natural selection produces organisms that have different structures or occupy different habitats. As a result, species today look different from their ancestors. • All living organisms are related to one another through common ancestors = common descent

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