The Theory of Evolution & Natural Selection

UNIT 7: Chapter 14-18

What is evolution?

A change in species overtime.

The Horse

Over 60 million years, the horse evolved from a dog-sized creature that lived in rainforests into an animal adapted to living on the plains and standing up to 2m high.

In the process, its multi-toed feet, adapted for walking across the forest floor, evolved into single-toed hooves more suited for running over open country.  

Charles DarwinDarwin was born in 1809. He sailed around the world (it took 5 years)He searched for scientific explanations for the diversity of life.Sailed on the HMS Beagle.He was a naturalist.

Charles Darwin’s Voyage

Charles Darwin

Wrote a book on the Origin of Species

Sailed with the HMS Beagle

Observations made in the Galapagos Islands

These observations helped him form the theory of how species change over time called natural selection

What did Darwin study?

Finches Tortoises

On the Galopagoes Island

What is Natural Selection?

Natural selection is governed by the principles of genetics.

Also known as “Survival of the Fittest”

Did the Biosphere adapt or evolve over time?

Pinta IslandIntermediate shell

Pinta

Isabela IslandDome-shaped shell

Hood IslandSaddle-backed shellHoodFloreana

Santa Fe

Santa Cruz

James

Marchena

Fernandina

Isabela

Tower

Giant Tortoises of the Galápagos Islands

Section 15-1

Evidence for Evolution

1. Fossil record

2. AnatomyHomologous structures

Analagous structures

3. Vestigial structures

4. Embryology

5. Molecular biology (DNA differences)

Mechanism for change in a population of organisms:

Animals who have greater fitness survive in environment and live to reproduce.

Random changes in DNA (called mutation) can lead to greater or less fitness.

Adaptations allow an organism to survive better in their environment.

Who’s More Fit…..

Bear without claws Bear with claws

Adaptations

large, flat feet, to spread their weight on the sand of their desert habitat

thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss

a large surface area to volume ratio, to maximise heat loss

the ability to go for a long time without water (they don't store water in their humps, but they lose very little through urination and sweating)

the ability to tolerate body temperatures up to 42°C

slit-like nostrils, and two rows of eyelashes, to help prevent irritation from sand.

a white appearance, as camouflage from prey on the snow and ice

thick layers of fat and fur, for insulation against the cold

a small surface area to volume ratio, to minimise heat loss

a greasy coat, which sheds water after swimming

Japanese Spider Crab

Types of Adaptations

Protective ColoringCamouflage

Mimicry

Physiological AdaptationsReproductive Changes

Other changes

Behavioral Adaptations

Peppered Moth Lab

DO NOW---What are some similarities amongst these birds?

Prehistoric Bird Turkey

Lamarck’s Theory of EvolutionSection 15-2

LAMARCK PROPOSED THAT IF AN ORGANISM USED OR DIDN’T USE ORGANS (OR BODY PARTS) WOULD CAUSE IT TO CHANGE OVERTIME. His hypothesis was incorrect!!!

Jean-Baptist Lamarck

French naturalist

Born before Darwin

First to form a hypothesis of evolution.

He finally realized organisms adapt to their environment—don’t loss or gain traits from lack of using organs.

Adaptations

Can arise in response to environmental pressures

Temperature

Antibiotic resistance in bacteria

Pesticide resistance

Morphological changes in peppered moths

Yellowstone Park Environment

America’s first national park

Variety of wildlife (grizzly bears, wolves, bison, elk)

Preserved national park

Located in Wyoming, Montana and Idaho

Bacteria can survive in 400 degrees F. This is an example of adaptation.

http://www.yellowstoneparknet.com/geothermal_features/hot_springs.php

What is a Population?

Populations are groups of interbreeding individuals that live in the same place at the same time.

Populations evolve over many generations, individuals don’t!

Individuals in a population compete for resources with each other.

How Does Evolution Work?

Populations produce more offspring than the environment can support.

The unequal ability of individuals to survive and reproduce leads to the gradual change in a population over many generations.

How are new species created?

Geographic isolation

Reproductive barriers

Change in chromosome numbers

Adaptive radiation

What is Extinction?

The Dodo Bird

Review Evolution:

1. What is evolution?

2. What is natural selection?

3. Who was Charles Darwin?

4. What are 5 evidences that support evolution?

5. Describe a younger and older fossil and ground layers they would be fossilized in.

Answers

1. A change in species overtime. 2. Favorable variations that enables an organism to

adapt successfully to a change in the environment.

3. He formed theory of evolution—species change overtime.

4. Fossil record, Anatomy, Vestigial structures, Embryology, Molecular biology

5. Younger layer would be in top ground sediment. Older layer would be below younger layer of fossil remains.