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Unit B Chapter 1
Transcript of Unit B Chapter 1
Extinction 65 Million years ago 90% of life died out Evolution-Theory theory that species change over time Traits can pass from one generation to the next Slowly these changes happen FOUNDERS of EVOLUTION Charles Darwin
Took a 5 year voyage around the world to develop his theory
Natural Selection: members of a species best suited to an environment reproduce more at a higher rate than other members of a species.
Most of his evidence was gathered through observations of turtles and finches on islands such as Barbados First to say species can adapt during their life and pass traits onto their offspring
His evidence was based off Giraffes' necks
- Each generation was reaching to higher leaves and thus pass that onto their offspring
*He had no real (concrete) evidence to support his ideas Jean- Baptiste de Lamarch You are running from a bear.... If you run faster than me, who is the bear going to catch? Who will be able to produce faster runners? You were able to adapt faster than me. Your natural born speed enabled you to produce more offspring with your similar speed. Darwin's Evidence
The finches and turtles at the Galapagos Islands had developed differently.
This was natural selection which supported his theory of evolution.
- Finches adapted with the size of their beaks depending on their food source.
- Turtles adapted by their body structure. Artificial Selection
When humans selectively
breed animals and plants Natural Selection three two one four If an animal produces enough offspring, some will survive. Over Production Think of Salmon: the lay thousands of eggs only a few hundred will survive against disease and predators in the streams they are layed in. Only a few dozen will live long enough to breed. Variation Natural differences that help different living things to survive. Predators- ability to catch their meals
Prey- ability to elude the predators Most of time these characteristics are mutations
such as the curved tail of the salmon allows it to swim faster. Adaptation An inherited trait that gives an organism an advantage Same species, different mouths to eat different things Selection Those animals born with a selective advantage will survive longer Uniformitarianism! http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html Let's Practice-Match the finches beaks with
the pictures on your desk. raise your hand
when you are done. Follow up:
1. What is natural selection?
2. How does natural selection support
evolution? Speciation The evolution of a new species from an existing one. What causes speciation? Usually physical isolation from each other and their ability to adapt to a new location Galapagos Islands turtles and finches Seperated by moutains. Separated by cannons Remember Evidence to Support Evolution
Genetics Comparing fossils over time shows that there is a connection. The geologic time scale helps to show this Comparing today’s animals and plants to those in the fossil record help to provide evidence
Vestigial Organs-are physical structures that were fully developed and functioning in an earlier group of organisms but are reduced and unused in later species. Elephant fossil timeline leads to one original ancestor Dog fossils and structures lead back to one original species Similar arm (wing) structure=similar ancestor More vestigial organ examples:
Wisdom teeth and appendix on humans
Wings on flightless birds
Leg bones on whales
Hind legs on dolphins Scientists can now examine the DNA of organisms and have also notices similarities in animals from the past and today.
Same “stuff” in different animals=common ancestor