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
Chapter 5 Section 1: Darwin’s Voyage
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
Darwin’s first stop was South America
In Brazil, Darwin saw amazing creatures, like giant insects and armadillos
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!!
Darwin’s next stop was the Galapagos Islands, off of the west coast of South America
Here Darwin encountered the giant tortoise
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 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
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…
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
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
“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
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.
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
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
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
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
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.
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.
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???