1.Variation2.Selection3.Heredity

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Variation exists in all populations (Siblings look similar…but not identical)

Causes of variation Mutations Sexual recombination▪ (mixing of parents traits)

Meiosis▪ (remember crossing over?)

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Malthus – There are limits to the sizes of populations Going to run out of SOME resource▪ Food, water, room, etc…

“Struggle for ” More individuals produced than can survive

Not everyone gets to live & reproduce

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existence

What are the two types of selection?1. Artificial Selection

Humans pick for certain traits

2. Natural Selection Nature selects for certain traits Traits that are most beneficial for an organism

Trait that would allow an organism to eat different kinds of food…

Trait that would make an organism have more offspring…

SomeSome traits are passed down from parent to child Acquired (gained) traits are

not passed down (Those with the best traits are more

likely to survive to reproducereproduce) (Its all about the reproductionreproduction) Reproduce and pass on your

better genes or go extinct!

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The new offspring should have most of the characteristics of the surviving parents (How is the information passed down?) (DNA!)

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1. Variation• Some lions will be faster and

stronger than others2. Selection• The fastest and strongest lions are

more likely to eat & survive longer• Longer survival = more

reproduction3. Heredity• Surviving lions will have

faster and stronger cubs8