Unit 8 Day 3

Natural Selection and Evolution NOTES

I CAN define evolution I CAN describe the process of

natural selection I CAN explain the process of

speciation

I CAN…

Evolution is the process by which species

change over time. This happens over a long period of time. Natural selection often happens due to a

change in environment (flood, fire, natural barriers such as mountains) that separates species geographically and causes them to adapt to their new environment.

Examples of three different species:

KP 1: What is Evolution?

Horses

Donkeys

Zebras

Evolution occurs through natural

selection. The organism that best fit their

environment survive and reproduce. Nature “selects” the genes that are best The parents reproduce and pass these

genes onto their offspring.

KP 2: How Does Evolution Occur?

Why do you think a polar bear is

better suited for the arctic environment than a grizzly bear?

Check for Understanding

Vs.

KP 3: How does Natural

Selection Work?

Principle Giraffe Example1. Genetic variation exists in populations and these variations can be inherited

Thousands of years ago some giraffes had longer necks and others had shorter necks.

2. Organisms compete for limited resources

Giraffes have to fight for food and shelter

KP 3: How does Natural Selection Work?

Principle Giraffe Example3. Organisms produce more offspring than can survive

Giraffes have more babies than the environment can support.

4. Individuals with the best traits survive and pass on these traits to their children.

Long necked giraffes survive and reproduce the most because they can eat the leaves on the tall trees= REPRODUCTIVE ADVANTAGE

SPECIATION: A species is a group of animals that…

1. have the same physical structure 2. can interbreed to produce fertile offspring (can

make their own babies) When natural selection causes a new species to

form, we call it speciation

KP 4: How do we get new species?