Change Over Time

Other Theories of Change Over Time Jean-Baptiste Lamarck: one of the first scientists to recognize that living things have changed over time. Lamarck’s Theory of Change Over Time: Tendency Toward Perfection Organisms continually change and acquire features that help them be successful in their environments. Use and Disuse Organisms could alter the size and shape of organs and limbs Example: organism trying to use front limbs to fly could transform the limbs into wings – OR – a bird not using it’s wings to fly could decrease the size of its wings over time.

Darwin’s Big Idea Charles Darwin traveled the world (in a boat) observing and collecting evidence of the way living things change over time. Darwin observed many organisms including beetles, finches (birds), tortoises, iguanas and various plants.

Darwin’s Theory 5 Points of Darwin’s Theory: Variation -Individual organisms differ –Some variation is heritable, or can be passed to offspring through DNA Over reproduction- Organisms produce more offspring than can survive, and many that do survive do not reproduce. Competition -for limited resources. Survival of the fittest, or natural selection. Those that survive and reproduce, will pass on their traits

Variation Among Individuals Characteristics of organisms vary: Height Body Color Speed Eye Color Reaction Time Hair / Fur Color Many others…

Over-Reproduction Production of more offspring than can survive, Fish Examples: Fish Plants Ducks Turtles

Competition Organisms compete for resources in order to survive. Resources include: Food Living Space Other things necessary for survival

Predators that are able to catch their prey more efficiently than other predators are more suited to survive in their environment. Prey that is able to hide, camouflage or defend itself, or outrun its predator, is better suited to survive in its environment.

Survival of the Fittest Adaptations play a key role in natural selection Adaptations increase an organism’s chance for survival by allowing it to become better suited for its environment. Examples: Porcupine quills; speed; camouflage

Fitness - If an organism is better suited for its environment, it will be able to reproduce . Over time, natural selection results in changes in inherited characteristics of a population.

Clicker Question Any inherited characteristic that increases an organism’s chance of survival is: a. fitness. b. adaptation. c. reproduction.

Those that survive and reproduce, will pass on their traits Darwin proposed that each living species has descended, with changes, from other species over time (millions of years). Over time, natural selection produces organisms that have different structures and occupy different habitats.

Evidence of Change Over Time Fossils Geographic Distribution of Living Species Homologous Structures: Vestigial Organs

Clicker Question a. vestigial organs b. adaptations Structures that have different mature forms but develop from the same embryonic tissue are: a. vestigial organs b. adaptations c. homologous structures d. fossils

Darwin’s Conclusions Through his observations, Darwin noticed variation among these organisms, and he also noticed similarities between fossils and living organisms. His observations led him to create a theory of how living organisms change over time.