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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

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Changes over time
Changes Over Time

Chapter 5 Section 1: Darwin’s Voyage


Charles darwin
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 darwin1
Charles Darwin

Darwin’s first stop was South America

In Brazil, Darwin saw amazing creatures, like giant insects and armadillos


Charles darwin2
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
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 islands1
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 islands2
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 islands3
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
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


Adaptations1
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
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
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
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 selection1
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 selection2
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 selection3
What Affects Natural Selection?

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
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 isolation1
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
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???


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