EVOLUTION Part I Change Over Time What is

EVOLUTION Part I: Change Over Time

What is Evolution? • The processes that have transformed life on earth from it’s earliest forms to the vast diversity that characterizes it today. A change in the genes over time!! (What does this mean? What will cause this? ) MUTATIONS!

Charles Darwin • • • 1809 -1882 Education: Edinburgh University Medical school – found it boring & didn’t like surgery • Learned about taxidermy from John Edmonstone, a freed slave, who encouraged Darwin to explore the world

Voyage of the Beagle

• Naturalist on The Beagle • Went on a 5 year voyage around the world, * Galapagos Islands * • Collected huge numbers of plant and animal specimens • Noticed there was tremendous diversity in the organisms he observed • From this experience, Darwin developed The theory of natural selection

Galapagos Islands

DARWIN’S FINCHES

Darwin’s theory of natural selection • Darwin hypothesized: • organisms look different because their environments are different. • differences allow each species to survive in its particular environment. • Example: the firefly beetle “glows” to attract a mate, insuring the survival of the species • Example: the vegetarian finch has a beak best suited to eating buds and fruit; an insect-eating finch has a different beak SURVIVAL OF THE FITTEST!!!

Natural Selection • Individuals with favorable traits are more likely to have and leave more offspring better suited for their environment

Chapter 7 Section 3 Natural Selection in Action

Charles Darwin • In 1859, he wrote: wrote • “On the Origin of Species by Means of Natural Selection” Two main points in the article: 1. Species were not created in their present form, but evolved from ancestral species. 2. NATURAL SELECTION is the mechanism for evolution

4 Main points of Natural Selection 1. There is variation within a population 2. Some variations are favorable 3. Not all young produced in each generation can survive 4. Individuals that survive and reproduce are those with favorable variations

“Survival of the Fittest? ” Natural Selection is sometimes referred to as ‘survival of the fittest. ’ What does this mean? ? • The fittest animal is the one that survives to reproduce, (reproduces the most), and pass on it’s genes to its children. • Who is most likely to survive this long? The animal best adapted to it’s environment!!

AN EXAMPLE: http: //www. techapps. net/interactives/peppe r. Moths. swf (I need some volunteers!)

Why/how did the giraffe get such a long neck? • Explain this using what you have learned about natural selection ( the 4 points).

4 Main points of Natural Selection 1. An early giraffe was born with a longer neck…. . (a CHANGE in her genes- a mutation!) 2. This giraffe was able to reach the higher, more plentiful leaves on the tree. 3. Many of her siblings with shorter necks did not survive (not enough food!). 4. She survived and had more offspring than other giraffes (& many of them had longer necks like Mom!).

Artificial Selection • The selective breeding of domesticated plants and animals by man. • Question: What’s the ancestor of the domesticated dog? • Answer: WOLF

Evidence of Evolution 1. Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence). 2. Homologous structures: Structures that are similar because of common ancestry (comparative anatomy)

Chapter 7 Section 1 Change over Time

Evidence of Evolution 3. Taxonomy: Classification of life forms. 4. Molecular biology: DNA and proteins (amino acids)

To summarize: Mutation Adaptation Speciation the process of evolution!

Gene Pool • The total collection of genes in a population at any one time.

Gradualism • Small genetic changes occur slowly within a population • Darwin originally proposed that evolution occurred at a slow, gradual rate

Punctuated equilibrium • 1972 - Stephen Jay Gould and Niles Eldridge • Populations stay stable for long periods of time, interrupted by brief periods of rapid change • Environmental change; increased mutation rate • Supported by fossil record

HW Review Questions 1. What is the mechanism for evolution? 2. When we say there is a “change in the genes” what does this mean and what does this have to do with evolution? 3. Create a situation where natural selection would occur and explain how and why it does occur. (This can be a situation about animals, plants, bugs, etc. ) 4. Discuss what a homologous structure is and explain how this can be used as evidence for theory of evolution. 5. Explain why Darwin found such a variety of finches (think beaks). How did this occur and why is this significant to his work?

Misconception: “Evolution is a theory about the origin of life. ” • Response: Evolutionary theory deals mainly with how life changed after its origin. Science does try to investigate how life started, but these are not the central focus of evolutionary theory. Regardless of how life started, afterwards it branched and diversified, and most studies of evolution are focused on those processes.

Misconception: “Evolution is ‘just’ a theory. ” • Response: Scientific theories are explanations that are based on lines of evidence, enable valid predictions, and have been tested in many ways. In contrast, there is also a popular definition of theory—a “guess” or “hunch. ” These conflicting definitions often cause unnecessary confusion about evolution.