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 (wanted to know how)

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

Charles Darwin -Wrote the book Origin of Species to propose that natural selection occurs in nature. (4 postulates) -1. organisms in a population vary in traits (characteristics) -2. these traits can be passed on to offspring. -3. more offspring are born than the environment can support. -4. the ones with traits that are helpful for survival and/or reproduction live and mate -over time the whole population can change, ending up with a certain trait. (size in humans, aggression in bees, sharp teeth in sharks, roots in plants. etc)

Natural Selection -change in populations traits over time (favorable traits are passed on to offspring) -traits must be heritable (passed by DNA) -selective pressure – factor that makes a trait favorable (predator, habitat, mate preference,food source, etc). -fitness level- how equipped an organism is for survival and reproduction

Adaptations -inherited traits that increase organisms’ chances of survival (moth color, cliff sheep hooves) -types of adaptations: behavioral, structural, physiological, ornamental, coloration

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