7.1 Darwin’s Voyage

A. Darwin

1. Charles Darwin was a British ______________________.

naturalist

2. He traveled for 5 years around the world on the ______________.

HMS Beagle

3. He noted that plants and animals were very different

from ones in England. He asked why….

a. This question led him to develop the theory of

____________________ by natural selection. evolution

B. Darwin’s Observations

1. During the voyage the Beagle stopped at the ______________

Islands which are off the coast of __________ ______________.

Galapagos

South America

2. While on the islands Darwin observed incredible animal _________.diversity

Lizards eating cactus

Insects mimicking plants

Giant Tortoises

Harriet DarwinThe Darwin Kids

C. Similarities and Differences (Mainland vs. Islands)

1. He noted similarities.

The mainland and islands both had similar plants and animals.

Example: ________________ and __________________iguanas finches

2. He also noted differences.

Example: Iguanas

-The mainland iguanas were ___________ and had _________claws

to climb trees and grasp leaves from the trees.

-The island iguanas were _____________ and had _________ claws

to hold onto slippery rocks and grasp seaweed.

green short

dark gray long

It appeared that once the mainland iguanas reached and inhabitedthe islands they reproduced, and eventually, over a ________ period of time, became different from their mainland relatives.

long

Example – Finches:

- Finches beak types were different from one island to the next.

Island A had lots of insects but not many seeds.

Their beaks were ____________ and _____________.

Island B had lots of seeds but not many insects.

Their beaks were ____________ and _____________.

narrow pointed

thick blunt

D. Evolution (From the Latin evolvere which means to unroll)

1. _____________ ____________ is a well tested concept or

idea that explains a wide range of observations.

2. How did this theory develop?

a. Darwin observed organisms on the Galapagos Islands that had

slightly different traits when compared to the same mainland

organisms. These slightly different traits which enabled them to

survive on the island are called __________________.

Adaptation – A _______ that helps an organism _________ and

_____________ more successfully in its

environment..b. He reasoned that the organisms on the island faced different

surroundings or _____________, compared to the mainland

organisms.

Scientific theory

adaptations

environments

trait survive

reproduce

c. He also reasoned that species gradually changed over many

______________ and became ____________________ to the

new island _________________.Environment -

All ________ and _____________factors that affect an organisms ability to ___________ and ________________.

(i.e. The place where you live )

generations better adapted

environment

living non-living

survive reproduce

E. Natural Selection

Darwin wrote a book called The Origin of _____________ that

proposed that evolution takes place by means of

___________ ___________.

Species

natural selection

Natural Selection is the process by which individuals that are better _____________ to their environment are more likely to __________ and _____________, passing on their genes to the next generation.

adaptedsurvive reproduce

1. There are __________ factors that affect natural selection.

a. ___________________- the production of more offspring than can possibly survive.

Baby Spiders

Overproduction

THREE

b. ______________- members of a species differ from each other.Variation

Pepper Moths

c. ________________- resources are limited and the offspring must struggle with each other for these limited resources. Some live, some die.

Competition

F. Environmental factors

1. As overproduction, variation, and competition persist in a population of living things, ______________ ___________ ultimately determine which individuals will survive long enough to reproduce, and pass on their __________ (DNA).

2. Over time, genes for __________ (helpful) traits are passed on more than ___________ ones, gradually leading to adaptations that are well suited to that environment.

Examples from the Galapagos:

Organism Environment Adaptation

Iguana Black-lava, - slippery coastline -

Cormorant Food-poor shore, - food-rich ocean -

Darker skinLonger Claws

Shortened wingsStream-lined body

environmental factors

genes

favorableunfavorable

Ex) Ground Finches of Daphne Major-

In _____ years, more small seeds exist. Individuals with _________ beaks survive and reproduce more.

***Over time, the average beak size of this population will _____________.

If conditions change, and _____ weather comes to the island, more large seeds will exist. Individuals with ________ beaks survive and reproduce more.

***The average beak size of this population will ___________.

wet smaller

decrease

drylarger

increase

3. __________ in the Environment drive evolutionary changeChanges

4) __________ or __________ environmental changes require rapid adaptations or a species can become ________!Sudden drastic

extinct

Ex) Marine Iguanas of Santiago

After the El Nino weather pattern dried up their food source, ________ iguanas on most islands were wiped out.

Smaller populations on Santiago, which had __________ to a diet of thinner algae, survived, resulting in the ________ __________ that exist today.

larger

adapted

smaller species