Change Through Time By: Susan Karikas

How did we get here from there? Mechanisms of evolution –Millions of different organisms inhabit our planet –Species reproduce their own types –Since the beginning of time organisms have changed and continue to change

Who thought of this stuff? Jean Baptiste de Lamarck –Early evolution theorist (1809) –French scientist hypothesized that offspring inherit traits that their parents developed throughout their life. Weight lifters develop muscle through hard work and not inheriting from their parents

Charles Darwin’s visit to the Galapagos Islands At the age of 22, Charles Darwin sailed on the HMS Beagle to South America He observed and recorded facts about plants, animals, and fossils –Giant cactuses, 13 species of finches, and huge land turtles He collected specimens –For 20 years he studied his specimens to come up with his hypothesis

Principles of Natural Selection Organisms with traits best suited to their environment are more likely to survive and reproduce Five factors involved in natural selection –Organisms produce more offspring than can survive; variations exist within species; these variations are passed on to offspring; some variations allow members of a population to survive; over time these helpful variations make up more of a population

Adaptation and Variation A variation is an inherited trait that makes one member different from another of the same species. Variations result in mutation of one’s DNA. –An example could be as simple as the shape of one’s hairline or as complex as fruits without seeds Some variations are more helpful than others Variations result in adaptations

Adaptations An adaptation is any variation that makes an organism better suited to its environment –Camouflage is an adaptation that allows an organism to blend into its environment and thus have a better chance of surviving and passing on helpful traits to its offspring

How fast does evolution occur? Scientists have different hypotheses on this issue. –Many believe evolution occurs over millions of years Gradualism –Others believe change occurs more quickly Punctuated equilibrium Evidence supports both models

Models of change: Gradualism and Punctuated Equilibrium Gradualism states that evolution is a slow, steady and ongoing process –Change of one species to another –Intermediate form of all species Punctuated Equilibrium states that evolution can occur more quickly through mutations in DNA –An example of this model is bacteria that is destroyed by antibiotics

How do we know this is true? Fossil evidence –Any evidence of life from an earlier geological time –Imprints of a leaf, feather, or organism in a rock –A piece of wood or bone –An organism frozen in ice –An insect or organism trapped in amber (think Jurassic Park)