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

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

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

Charles Darwin There is a huge amount of diversity in South America There are many different species of animals and plants A species is a group of similar organisms that can mate with each other and produce fertile offspring If the offspring is not fertile, the parents are not the same species Horse + Donkey = Mule (not fertile) There are 2.5 million species of organisms on Earth!!

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

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

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

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

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

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

Adaptations Finches have different beaks to help them eat their food. Large wide beaks to crack hard seeds Long sharp beaks to hunt and eat insects

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

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

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

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

What Affects Natural Selection? Variations A variation is a difference in traits that members of the same species may have. Examples of variations: Parrots with different colors Turtles that swim faster than others

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

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

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

Continental Drift Many millions of years ago, all of the continents were Over time, the continents drifted away from each other This was caused by Continental Drift What do you think happened to many species after the continents separated???