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