The Organization of Life Section #2: Evolution. How do organisms become so well suited to their...
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Transcript of The Organization of Life Section #2: Evolution. How do organisms become so well suited to their...
The Organization of Life
Section #2:Evolution
How do organisms become so well suited to their
environment?
• Charles Darwin (1859)• proposed his theory of evolution• observed that organisms in a
population vary slightly in form, function, & behavior from each other
• some of these differences are hereditary – passed from parent to offspring
Natural Selection
• the unequal survival and reproduction that results from the presence or absence of particular traits
• the environment exerts a strong influence over which individuals will survive and thus reproduce
• individuals with certain traits will have a better chance of surviving
Evolution of thicker fur in a population of deer:
Evolution
• Darwin proposed that over many generations, natural selection causes the characteristics of populations to change1. organisms produce more offspring than can
survive2. the environment is hostile and contains
limited resources3. organisms differ in the traits they have4. some inherited traits provide organisms with
an advantage5. each generation contains proportionately
more organisms with advantageous traits
Video Clip:Natural Selection
Adaptations
• an inherited trait that increases an organism’s chance of survival and reproduction in a certain environment
Video Clip:Adaptations
Coevolution
• the process of two species evolving together in response to long-term interactions with each other
Example:the lobelia flower has developed a structure to ensure that the Hawaiian honeycreeper bird gets pollen on its head when it sips the sweet nectar through its long curved beak
Artificial Artificial SelectionSelection
• the selective breeding by humans for specific characteristics
Resistance
• the ability of one or more organisms to tolerate a particular chemical designed to kill it
• Examples:– bacteria’s resistance to certain
antibiotics– insect’s resistance to pesticides– weed’s resistance to herbicides
Video Clip : Resistance