Darwins Theory of Evolution by Natural Selection 15

Darwin’s Theory of Evolution by Natural Selection 15. 1

Charles Darwin • English Biologist • Collected fossils, plants, rocks, and animals while doing research in the Galapagos Islands. • Before his research, the planet was thought to only be about 6000 years old and that plants/animals never changed.

Charles Darwin • While exploring the Galapagos islands, Darwin observed each island had its own slightly different variety of animals. • Almost every specimen Darwin brought back to England was new to English scientists. • Darwin suspected that populations from the mainland changed after reaching the Galapagos islands.

Natural Selection V. Artificial Selection Natural Selection • The idea that, if left unchecked, undesirable traits within the human population will slowly be weeded out due to their inability to compete to survive. Reproducing without interference. Ex: giraffes with short necks are no longer in existence because they couldn’t compete with long-necked giraffes for food in high places. Artificial selection • The idea of directed breeding to produce offspring with desired traits. Ex: breeding a Labrador retriever with a poodle to get a curly, long haired dog called a labradoodle.

Darwin’s principles of Natural Selection 1. Individuals in a population show differences , or variations. 2. Variations can be inherited, passed down from parent to offspring. 3. Organisms have more offspring than can survive on a available resources. 4. Variations that can increase reproductive success will have a greater chance of being passed on than those that do not increase reproductive success.

Darwin’s theories explained 1. Individuals in a population show differences , or variations. 2. Variations can be inherited, passed down from parent to offspring. 3. Organisms have more offspring than can survive on a available resources. 4. Variations that can increase reproductive success will have a greater chance of being passed on than those that do not increase reproductive success. • Basically, not all offspring will be able to survive because there aren’t enough resources for every offspring to survive. • Only those that have favorable variations will survive. • Eventually, the unfavorable variations will be weeded out as those carrying those variations will die and not pass on their variations. • This could eventually lead to the creation of a new, more favorably varied species which is unique from the original.

Evolution • Evolution- cumulative changes in groups of organisms over time. Ex: people grow in size and mentality over time from birth to adulthood. Evolution DOES NOT mean humans came from monkeys!!!

Key points • Charles Darwin completed the original research that suggested that organisms change over time. • These changes can lead to the creation of new species. • These changes over time are referred to as evolution. • Evolution is not the idea that humans came from monkeys.