Darwin and Natural Selection

Charles Darwin (born 1809) -sailed on the HMS Beagle for 5 years studying organisms around the world (many in the Galapagos) -Noticed similarities amongst organisms around the world (wanted to know how)

Artificial Selection Noticed that humans grow crops and breed animals to get the most useful traits in offspring (ex. cows with more milk, biggest vegetables,) -called this artificial selection.

Charles Darwin -Concluded that natural selection can occur too . -1. organisms in a population vary in traits -2. these traits can be passed on to offspring. -3. more are born than the environment can support -4. the ones with the best traits live to pass them on Ex. Sharp teeth in sharks

Natural Selection -natural selection -change in populations traits over time (must be heritable [in genes]) -selective pressure – factor that makes a trait favorable (predator, habitat, food source, etc). -fitness level- how equipped an organism is for survival and reproduction

Adaptations -inherited traits that increase organisms’ chances of survival (color, claws)

Structural Adaptations -physical structures that increase an organism’s fitness level

Coloration Camouflage- blend in with surroundings Mimicry- imitate other organisms

Ornamental -structures that attract mates

Physiological Changes in the body to increase fitness level (ex. immunity)

Behavioral -behaviors that increase fitness