2. History of Biological Diversity Evolution: Darwin’s travel

3. Developing the Theory of Evolution The Galápagos Islands
Darwin noticed that the different islands all seemed to have their own, slightly different varieties of animals.
Somewhat similar species that suited their particular environment.
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Darwin’s Theory of Evolution by Natural Selection

4. Origin of Species: Darwin’s Book
In 1859 On the Origin of Species presented evidence and proposed a mechanism for evolution that he called natural selection.

5. Video of Darwin

6. Natural Selection is Survival of the fittest
Natural selection is a process of elimination
ORGANISMS THAT HAVE TRAITS THAT ARE BEST ADAPTED FOR THE CURRENT ENVIRONMENT ARE THE ONES THAT SURVIVE TO BREED AND PASS ON THEIR GENES TO THE NEXT GENERATION, CAUSING A CHANGE IN THE OVERALL POPULATION.
Organisms not possessing the beneficial traits either die or don’t have as many offspring.
Natural Selection is Survival of the fittest
Biological fitness- ability of an organism to survive AND reproduce (pass on its genes)

7. Main Points of Natural Selection
Genetic Variation is present in the population and it is inherited (passed to offspring)
-Mutations: Changes in the DNA
-Meiosis: crossing over Random mate selection & fertilization
Living Things Overproduce Offspring (not all survive)
Competition for Limited Resources
Survival of the “Fittest”

8. Natural Selection Fitness Differential Reproductive Success Genetic
Limited
Resources
Genetic
Variation
Fitness
Competition
Organisms produce more offspring than can survive.
Environmental Factors
Differential
Reproductive
Success
Natural Selection
Differential reproduction is the idea that those organisms best adapted to a given environment will be most likely to survive to reproductive age and have offspring of their own
Make sure students know the definitions to the following terms: genetic variation, fitness, competition, resources, and environmental factors.
Take time to explain how the various components lead to DRS.

11. Adaptations-a change or the process of change by which an organism or species becomes better suited to its environment.
Types of adaptations
Camouflage is a suite of morphological adaptations that allow an organism to blend into its environment.
Mimicry is a type of morphological adaptation where a species evolves to resemble another species.
Antibiotic resistance develops in some bacteria,making them able to survive antibiotic treatments
Mimicry
Camouflage

12. Peppered Moth: Natural Selection
The light colored form was the predominant form in England prior to the Industrial Revolution.
Around the middle of the 19th century the darker form began to appear. It was first reported in By % of the moths in Manchester were the dark variety.
In recent years, the burning of cleaner fuels and Clean Air regulations has reduced the pollution there and the lighter colored moths have increased in numbers.

13. Natural Selection is Survival of the fittest
Natural selection is a process of elimination
ORGANISMS THAT HAVE TRAITS THAT ARE BEST ADAPTED FOR THE CURRENT ENVIRONMENT ARE THE ONES THAT SURVIVE TO BREED AND PASS ON THEIR GENES TO THE NEXT GENERATION, CAUSING A CHANGE IN THE OVERALL POPULATION.
Organisms not possessing the beneficial traits either die or don’t have as many offspring.
Natural Selection is Survival of the fittest
Biological fitness- ability of an organism to survive AND reproduce (pass on its genes)

14. Crossing Over Mutations Natural Selection Gene Flow Genetic Drift
Recombination
Gene Flow
Genetic Drift
Mutation
Selection
Gene Flow
Genetic Drift

15. Recombination: Crossing Over
Crossing over leads to genetic variation.
Crossing over is why siblings can have the same parents but still may look very different (except for identical twins etc.).

16. Not every mutation has a visible effect.
Mutation & Variation
Mutation creates variation
new mutations are constantly appearing
Mutation changes DNA sequence
changes amino acid sequence
changes protein’s:
Structure
function
changes in protein may change phenotype & therefore change fitness
Every individual has hundreds of mutations
1 in 100,000 bases copied
3 billion bases in human genome
But most happen in introns, spacers, junk of various kind
Not every mutation has a visible effect.
Some effects on subtle.
May just affect rate of expression of a gene.

18. Gene Flow Movement of individuals & alleles in & out of populations
seed & pollen distribution by wind & insect
migration of animals
sub-populations may have different allele frequencies
causes genetic mixing across regions
reduce differences between populations

19. Genetic drift Effect of chance events founder effect bottleneck
small group splinters off & starts a new colony
Skews the gene pool of the new population
bottleneck
some factor (disaster) reduces population to small number & then population recovers & expands again
alleles lost from gene pool, narrows the gene pool
1 family has a lot of children & grandchildren therefore has a greater impact on the genes in the population than other families
Genghis Khan tracked through Y chromosome.

21. How Evolution Occurs
There are two scientific theories regarding how evolution occurs.
Punctuated Equilibrium: This theory proposes that throughout geological time, biological species go through long periods of little change and then have brief periods of rapid change.
Gradualism: This theory proposes that throughout geological time, biological species gradually undergo changes that leads to speciation.
This will be explored more in the next lesson.