Evolution

Natural and Artificial Selection

Artificial selection- humans select which traits will be passed on

Natural selection- the environment determines which traits will

be passed onStruggle for existence-

organisms fight for resourcesFitness-

best traits for the environmentAdaptation-

an INHERITED good traitSurvival of the fittest-

those organisms best suited to the environment will survive and reproduce

What do you need to survive?

How did squids acquire this ability? Why?

http://www.youtube.com/watch?v=5Il14q63sv4

Imagine you are an ancient species of giraffe…

Goal: Eat the leaves on the tree. But there are rules. • Tall Giraffes eat first•Can only eat 5 leaves at a time•Can not hop, jump or stand on tippy toes or any other object. (like a chair)•As soon as leaves are out of reach sit down. •Must take turns. 1 at a time. •Do not throw leaves away•Do not exhort yourself. Eat the easiest leaves to get first.

NATURAL SELECTION ACTS ON THE PHENOTYPE, NOT THE GENOTYPE!!It only matters how the organisms traits are expressed- nature doesn’t know exactly what the genes are inside, only what it looks like or acts likeThis giraffe could be TT or Tt- you cannot tell from the outside!!!

Artificial selection/selective breeding

• Darwin noticed that humans “selected” and bred certain plants and animals to get the desired traits.

• Nature provides the variation. Humans choose the most useful.

http://learn.genetics.utah.edu/content/variation/artificial/ Natural vs artificial

In your own words what is the difference between natural and artificial selection?

The ability of an individual organism to survive and reproduce in it’s natural environnent is called what? A. EvolutionB. Natural SelectionC. AdaptationD. Fitness

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Natural Selection• He also noticed that some organisms

in nature were “selected” to survive and reproduce in certain environments

 

Finches on different islands looked so different from one another because their beaks were shaped to eat different foods (in different habitats).

Example:

Descent with ModificationDarwin also believed that natural selection produced organisms with different structures, niches, and habitats

Survival of the Fittest• Members of a population that have

desirable traits (the most “fit”) will have a greater chance to survive and reproduce in that environment.

• The most “fit” will be “selected” to thrive, reproduce, and survive.

• Those with less desirable traits will be “selected” to die or leave fewer offspring.

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.htmlhummingbirds

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How is Natural Selection related to species fitness?

Quick Check

A.FitnessB.Adaptation

C.Artificial Selection

The corn most of us eat today is very different from it’s ancestor. This is a result of what?

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The ability of an individual to survive and reproduce in its environment is called fitness.

An adaptation is any INHERITED characteristic that increases an organism’s chances of survival.

EVOLUTION takes place over a period of time. And is used to describe entire generations not simply individuals.

  

Fitness is a result of A. Going to the gymB. AdaptationsC. Artificial SelectionD. Natural Selection

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In 5 generations of birds, some were able to survive and reproduce better than others.

Give some possible reasons why it might be more difficult for the lighter birds to survive and reproduce?

Risk Box

http://www.pbs.org/wgbh/nova/evolution/evolution-action.html evolution interaction

Watch this:

What to put on the notecard:• Observations• Questions

What is the definition of a species? Members of the same species can successfully reproduce.

Descent with modification: Every living species has evolved, over time, with changes, from other species

 

 

Common descent: all

living organisms are related

http://learn.genetics.utah.edu/content/variation/recipe/

Watch this:

Q: Which of these best illustrates natural selection?

A. An organism with favorable genetic variations will tend to survive and breed successfully.B. A population monopolizes all of the resources in its habitat, forcing other species to migrate.C. A community whose members work together utilizes all existing resources and migratory

routes.D. The largest organisms in a species receive the

only breeding opportunities.

Q: A species of finch has been studied on one ofthe geographically isolated Galapagos Islands for many years. Since the island is small, the lineage of every bird for several generations is known. This allows a family tree of each bird to be developed. Some family groups have survived and others have died out. The groups that survive probably have

A. interbred with other species.B. inherited some advantageous variations.C. found new places on the island to live.D. been attacked by more predators.

Advantage- something that

helpsDisadvantage-

something that harms

Peppered moths – natural selection in action• Two forms- one dark, one light.

• In less polluted areas with cleaner bark on trees and buildings, the light moths were better camouflaged, and were more likely to pass on their light genes

•In heavily polluted areas, the dark moths were more common because they were better camouflaged.

• This shows that the environment can causes changes in species over several generations.

Next slide

Time for a POP

QUIZ!!!

Evidence for evolutionFossil record: what are fossils, How old is the Earth? How can scientists use fossils to document (record) the fact that life on Earth has changed over time? Have all the fossils been found?

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.htmlWhales

Geographic distribution of living things: Why were there so many differences between the finches on the Galapagos? What is it called when species evolve, over time, with changes, from other species? What did Darwin find on different continents, but in similar habitats?

Homologous body structures: how are certain body parts similar (in animals with backbones)? How and why have their limbs adapted? Give examples of homologous structures. What are vestigial organs?

Similarities in Embryology: How do the early-stage embryos of vertebrates compare to each other? What do these similarities mean? How do embryonic cells develop? What do they develop into?

http://www.pbs.org/wgbh/nova/evolution/guess-embryo.html guess the embryo

Genetic variation: differences in alleles and genes within and among populations (all lions are not exactly alike, all beetles, pine trees, humans, giraffes- are not exactly alike. 

Genetic variation is caused by

1. Mutations

2. Gene shuffling during sexual reproduction- during meiosis and crossing over

3. Gene flow, or migration 

Evolution is any change in the relative frequency (percentage) of alleles in a population

Gene pool- all the alleles in a population

 

 What is the definition of a species? Members of the same species can successfully reproduce.

Whale evolution: http://www.youtube.com/watch?v=8cn0kf8mhS4&feature=related