EVOLUTION

VERY SIMPLY PUT-- Evolution is change in a species over time.

How long did it take to CHANGE? 66 million years ago 54 million years ago 37 million years ago 26 million years ago Present Day

There are two models for HOW this change occurs. Gradualism Punctuated Equilibrium The model of evolution in which gradual change over a long period of time leads to species formation. The model in which periods of rapid change in species are separated by periods of little or no change.

We have learned about the origins of evolutionary thought. 1787- The U.S Constitution is signed 1798- Thomas Malthus 1831- Charles Darwin 1858- Alfred Wallace 1773- Boston Tea Party Share out some of the contributions of the scientists that led to today’s model of evolution. 1785- James Hutton 1809- Jean-Baptiste Lamarck 1833- Charles Lyell 1850- California Gold Rush 1859- Darwin publishes The Origin of the Species 1861- U.S. Civil War Begins

Who was Charles Darwin?

How did Darwin come up with the theory of natural selection? He collected evidence in the Galapagos Islands that pointed towards his theory of natural selection. Geological Formation of the Islands Darwin’s Finches Adapted to their Food Source The Galapagos Tortoise

What is natural selection? In a nut shell… easier to survive more likely to reproduce Better traits Over time better traits dominate a population

What type of mouse is more likely to survive to produce offspring?

Survival of the Fittest Biological Fitness Fitness—an organisms ability to reproduce and pass their genes on to their next generation Survival of the Fittest Those who are more “Fit” will be more likely to survive. More Likely To Survive and Reproduce More Attractive Smarter Stronger

Which species is most fit for this exam? Why?

What did Darwin call the process? Quick Question Natural Selection What did Darwin call the process? Organisms well suited to their environment a. reproduce at a greater rate than those less suited to the same environment. b. are always larger than organisms less suited to that environment. c. always live longer than organisms less suited to that environment. d. need less food than organisms less suited to that environment.

Natural Selection… …is the process by which individuals that have favorable traits and are better adapted to their environment survive and reproduce more successfully than less well adapted individuals…

…is a process that occurs when four principles are true Natural Selection… …is a process that occurs when four principles are true

Principles of Natural Selection Genetic variation exists in a population and is inherited Genes = Traits Genetic Variation = Variation in Traits

Principles of Natural Selection 2. Populations tend to produce more offspring than can survive - more is better! WHY?

Principles of Natural Selection 3. The environment presents challenges to survival (resources are limited, competition for food, mate, territory)

Principles of Natural Selection 4. Individuals that are better able to cope or have advantages over another will leave more offspring. All of this leads to…survival of the FITTEST!!

Successful reproduction of the fittest members of a population eventually leads to an adaptation within that population. Adaptation A trait produced by natural selection that has become common in a population because it provides a selective advantage.

Organisms adapt to their environments in many ways…

Conserves water – not stored in hump Stored fat provides insulation Storage Adaptations Conserves water – not stored in hump Stored fat provides insulation

Reproductive Adaptations

Protection

Camouflage Fish Wasp moth Owl moth

Adaptations to food Parasite orchids Specialized beaks Specialized teeth Parasite orchids Parasitic Carnivorous plants

Plant adaptations Wind dispersal Water dispersal Animal dispersal

So how do adaptations occur?

Other Mechanisms of Evolution that lead to adaptations. Mutations/Recombination Gene flow (migration) Genetic drift

Mutations/Recombination A mutation is any change to the genetic material of a cell. What is the genetic material of a cell? DNA DNA code for genes, which are responsible for the traits we see. A mutation could cause parents with genes for bright green coloration to have offspring with a gene for brown coloration. That would make the genes for brown beetles more frequent in the population. Mutations may produce a different trait that may be an advantage for a species. Recombination is the mixing of genes to create/pass on traits

Gene Flow (Migration) Some individuals from a population of brown beetles might have joined a population of green beetles. That would make the trait and therefore the genes for brown beetles more frequent in the green beetle population.

Gene Flow (Migration) The amount of gene flow within a population varies. Very mobile organisms have a higher rate of gene flow than organisms that are immobile. Which would have a higher rate of gene flow? This is corn.

Effects of Gene Flow on Evolution Within a population Across populations Can introduce traits and therefore the genes that encode them into a population increasing genetic variation Can make distant populations genetically similar to one another. When the brown beetle joins the green beetle population, the brown beetle traits and therefore its genes enter the populations gene pool.

Genetic Drift A random change in the frequency of a trait that occur in small populations. Several green beetles were killed when someone stepped on them and had no offspring. The next generation would have a few more brown beetles than the previous generation—but just by chance. Therefore the frequency of the “green beetle trait” would decrease.

Genetic Drift Bottleneck effect Founder’s effect Can decrease genetic variation, especially in small populations! Bottleneck effect Population’s size is reduced for at least one generation Reduced variation may affect the ability to adapt to natural selection pressures- climate change, shift in resources. Founder’s effect A new colony is started by a few members of the original populations. Colony will have reduced genetic variation.

SPECIATION How do these changes lead to the formation of new species? Eventually the gene pools of the populations become too different. The populations can no longer interbreed. This is called REPRODUCTIVE ISOLATION.

Why does evolution matter now? If it happens as a long slow process, how does it affect me?

Tampering with Evolution Artificial Selection –Humans breed organisms for specific traits Interbreeding animals that would not normally interbreed in nature to create new species

Artificial Selection is an example of evolution where humans choose which plants/animals reproduce to make cuter pets or better crops. We like to call it “breeding”. Wild tomatoes Tomato crop Cockapoo