Natural Selection Demo

Early Evolutionary Theory Where did the Theory of Evolution Come From?

Jean-Baptiste Lamarck (1744-1829) Created an incorrect Theory of Evolution based on the inheritance of Acquired Characteristics

Lamarck Incorrectly Believed… That special use of a body part would change the genetic make up of that part. He believed that giraffes originally had shorter necks & since food was scarce, they reached for leaves in tall trees. This caused their necks to stretch. Offspring inherited this trait.

Charles Darwin (1809 – 1882) “Father of Evolution”

Voyaged to the Galapagos Islands on H. M. S Voyaged to the Galapagos Islands on H.M.S. Beagle (1831-1836) as the ship’s naturalist. Recognized that populations respond (over many generations) to changes in their environments. Example: Finches

The finches he studied had differently shaped beaks depending on where they lived and what they ate.

Who is Charles Darwin? Video Clip! Jot down some key points about Darwin and his discoveries!

Alfred Russell Wallace Was also voyaging and observing similar things to Darwin. Sent an essay to Darwin that did not use the term “natural selection” but described the same ideas. Darwin published their ideas in a paper on the theory of evolution.

Natural Selection Conditions in nature determine which organisms survive and reproduce a process that leads to evolutionary change

3 Conditions Required for Natural Selection

1. Inherited Variation Variation due to genetic causes individuals with certain types of inherited variation are better adapted to life in their environment than other individuals.

Examples: #1: Predatory species with longer claws and sharper teeth can catch more prey #2: Species that can camouflage can avoid being eaten

2. Overproduction of Offspring Populations produce more offspring than can survive.

3. The Struggle to Survive There is a continual struggle for existence in nature. Members of a population will compete for available resources.

Natural Selection results in only some individuals surviving… Survival of the Fittest!

Fitness How well an animal can survive and reproduce Fitness does NOT necessarily mean the strongest. The fittest individuals leave the most offspring.

What do you think will happen over time to this beetle population?