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Charles Darwin

Survival of the Fittest. Charles Darwin. Darwin’s Main Thoughts. Decent with modification Similar environments have similar looking animals Ex. European Hare and the Patagonian Cavy of South America Related species could be modified according to environment

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Charles Darwin

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  1. Survival of the Fittest Charles Darwin

  2. Darwin’s Main Thoughts • Decent with modification • Similar environments have similar looking animals Ex. European Hare and the Patagonian Cavy of South America • Related species could be modified according to environment • Natural selection

  3. Darwin’s Observations • In the Galapagos islands each island had animals adopted to its conditions Ex. Multiple tortoises, long-necked tortoises inhabited areas with scarce low- growing vegetation and short- necked tortoises inhabit areas with this low- growing vegetation • The finches developed different beaks to survive on the available food supply Ex. Ground dwelling finches have beaks adapted to eating seeds, tree dwelling finches have pointed beaks for eating insects out of trees, and cactus-eating finches have really pointed beaks for getting the pulp out of cactus friut.

  4. Basis for Natural Selection • Organisms have inheritable variation • Organisms compete for available resources • Individuals within a population differ in terms of their reproductive success • Organisms become adapted to conditions as the environment changes

  5. Inheritable Variation • Members of a population vary in functional, physical, and behavioral characteristics • Darwin emphasized variation is required for the process of natural selection • Variation can be harmful, helpful, or neutral - Harmful: Eliminated - Helpful: Survives - Neutral: Ignored

  6. Competition for Resources • Population growth based on available resources • Not all offspring born to a population can be supported by resources Ex. If elephants who live about 100 years and reproduce for half that time, then over the course of 750 years a single pair of elephants could have around 19 million descendants!

  7. Reproductive Success • Animals with the more favorable traits get the resources • Darwin defines fitness as the reproductive success of an individual • The most fit get the most resources and have the most offspring

  8. Organisms Adapt • An adaption is an evolved trait that helps an organism be more suited for its environment • Noticeable when unrelated animals have similar traits - water: animals have flippers - land : animals walk • Natural selection is the only evolutional process that involves adaptation to the environment

  9. Observations of Natural Selection • Peppered moths- due to industrial pollution the dominant light-colored moth became less abundant then the dark-colored moth until legislation reduced pollution and the dark- colored moth population began to decrease • Bacterial resistance to antibiotics- bacteria adapt to antibiotics that are overused and eventually become resistant to the medicine

  10. Human Influence • Humans have genetically modified animals for specific traits for years • This human- controlled breeding for desired traits is known as artificial selection Ex. Dog breeds bred for desired traits all with a common ancestor Ex. Fruits and vegetables are modified to be a more efficient sources of food

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