Recall…What is an adaptation? A trait an organism has that helps it

survive in its environment.

What is a variation?

Physical differences in species Ex hair color, fur color, size, etc.

Adaptations and the environment Organisms adapt to their changing

environment. Parents pass on adaptations to

offspring.

Causes of Adaptations

Sexual Reproduction Mutations-a change in the genes of

an organism. Random mutations occur during

sexual reproduction that change an organisms traits.

Good mutations give good traits and cause adaptations (traits get passed down to future offspring).

Bad mutations kill the organism (traits do not get passed down).

Natural Selection

Charles Darwin The process by which organisms that

have the best traits for an environment (best adaptations) survive and reproduce.

Survival of the fittest.

Steps of Natural Selection Step 1: Overproduction

More offspring then can survive.

Step 2: competition The struggle among organisms for food,

shelter, and mates.

Step 3: Variations Good (adaptations) and bad

Step 4: selection The best adaptations survive and

reproduce, passing on those adaptations.

Peppered Moth

Found in two forms, white and black. Before the growth of factories, most

peppered mouths were white. After the industrial revolution

(factories) over 98% of peppered moths were black….WHY??

Charles Darwin

A naturalist who sailed the world on the HMS Beagle.

Studied the diversity of living animals as he traveled.

Galapagos Islands

Iguana’s on the Galapagos Islands had larger claws than those on the mainland. They used these claws for climbing rocks

and eating seaweed.

Darwin also noticed differences between tortoise’s on different islands. On each island, the tortoises had unique

shells. One could tell the island the tortoise

came from by looking at their shell (ex: dome shaped shells vs saddle shaped shells).

Finch Beaks