Changes Over Time Chapter 5 Section 1 Darwins

Changes Over Time Chapter 5 Section 1: Darwin’s Voyage

Charles Darwin ØCharles Darwin was an English naturalist on the British naval ship HMS Beagle ØA naturalist is a person who studies the natural world ØOn Darwin’s journey, he made many observations that led him to develop theory of Natural Selection

Charles Darwin ØDarwin’s first stop was South America ØIn Brazil, Darwin saw amazing creatures, like giant insects and armadillos

Charles Darwin ØThere is a huge amount of diversity in South America ØThere are many different species of animals and plants ØA species is a group of similar organisms that can mate with each other and produce fertile offspring ØIf the offspring is not fertile, the parents are not the same species ØHorse + Donkey = Mule (not fertile) There are 2. 5 million species of organisms on Earth!!

The Galapagos Islands ØDarwin’s next stop was the Galapagos Islands, off of the west coast of South America ØHere Darwin encountered the giant tortoise

The Galapagos Islands ØDarwin observed that many of the plants and animals on the Galapagos were similar to the ones on the mainland. ØBUT…there were some key differences

The Galapagos Islands ØDarwin observed that many of the plants and animals on the Galapagos were similar to the ones on the mainland. ØBUT…there were some key differences ØEg The comorants on the mainland could fly, but those on the Galapagos couldn’t

The Galapagos Islands ØThe iguanas of the Galapagos have large claws so they can grip slippery rocks ØThe iguanas on the mainland had smaller claws so they can climb trees

The Galapagos Islands ØDarwin realized that some how, these animals came from the mainland eventually started to become different from their “distant cousins” ØThese organisms began to adapt…

Adaptations ØAn adaptation is a trait that helps an organism survive and reproduce ØDarwin observed birds called finches. ØThere were different types of finches that Darwin studied, each with a different shape beak

Adaptations ØFinches have different beaks to help them eat their food. ØLarge wide beaks to crack hard seeds ØLong sharp beaks to hunt and eat insects

Evolution Ø“Survival of the fittest” ØDarwin believed that species gradually change over time…this is Evolution ØSpecies change and adapt so that they can survive when their environments change

Natural Selection ØIn 1859, Darwin wrote the book The Origin of Species ØIn this book, Darwin explained that evolution happens because of natural selection ØNatural Selection is the process by which individuals that are better adapted to their environment are more likely to survive.

What Affects Natural Selection? ØOverproduction ØSome species have many babies at one time ØExample: Sea turtles lay 100 s of eggs ØWith so many offspring produced, there won’t be enough resources for all of the baby sea turtles Ø**Remember** All organisms need food, water and living space

What Affects Natural Selection? ØCompetition ØIf there are not enough resources, organisms will have to compete for food, water, and a place to live ØSome times there are fights for territory ØSome times it’s a competition of “who can run the fastest” from predators Ø**Remember** The masked booby chicks that fight to see who will be the one to survive

What Affects Natural Selection? ØVariations ØA variation is a difference in traits that members of the same species may have. ØExamples of variations: ØParrots with different colors ØTurtles that swim faster than others

What Affects Natural Selection? ØSelection ØSome individuals are better adapted to their environment than others because of their traits ØThey are the ones that are “selected” to survive and reproduce ØThe individuals that don’t have these adaptations won’t survive

Geographic Isolation ØIsolation is the complete separation. ØIsolation happens when one group of a species is “cut off” from the rest of the species ØGeographic Isolation is when a group is isolated because of a river, volcano, mountain range, etc.

Geographic Isolation ØThe two separated groups begin to adapt to their specific environment and develop different traits. ØWhen this happens a new species forms. ØThe Northern and Mexican Spotted Owl is an example of this.

Continental Drift ØMany millions of years ago, all of the continents were ØOver time, the continents drifted away from each other ØThis was caused by Continental Drift ØWhat do you think happened to many species after the continents separated? ? ?