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What is Natural Selection?

What is Natural Selection?. The Theory of Natural Selection explains how one species might be able to change into another. Evolution Species slow change over millions of years Descent with modification from a common ancestor Random *arguable. Creation Intelligent Design (ID)

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What is Natural Selection?

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  1. What is Natural Selection? The Theory of Natural Selection explains how one species might be able to change into another

  2. Evolution Species slow change over millions of years Descent with modification from a common ancestor Random *arguable Creation Intelligent Design (ID) Species show characteristics of design and intent Natural selection allowed genetic traits to emerge Not random The Controversy?!

  3. Changing PopulationsFacts Involved… • Species DO change • Adaptation • Genotype • Resistance to disease • Immune systems adjusting to contagions/poison • Competition for … • Breeding rights/mating • Survivability - Food, fighting, etc…

  4. Adaptation to Hunting • Most African Elephant males grow tusks • In the 1930’s less than 1% of the male elephants were born tuskless • Today 15% of male elephants are tuskless!

  5. Adaptation to Hunting cont… • Why the change in tuskless elephants? • Before they were a protected species hunters hunted elephants for the ivory of their tusks • With less elephants with tusks, the tuskless were able to breed more • And therefore there are more elephants without tusks than there was before

  6. Insecticide Resistance • When using insecticides most of the insects die (99%+) • The 1% that does not die can pass this immunity on to the next generation • Soon most of the insects will have this resistance

  7. Competition for Mates • Breeding to guarantee the survival of the species • When choosing mates, specific adaptations will be selected. • Coloring • Strength • Stamina

  8. Forming New SpeciesFacts Involved… • A species is a group of organisms that can mate and produce fertile offspring • Speciationoccurs when a group becomes separated from the original population & forms a newspecies with different characteristics, habits &/or diet • The finches of the Galapagos Island is the most often used example.

  9. Forming New Speciescontinued… • 3 basic steps toward Speciation • 1 - Separation • Separating from the “parent” group • Due to environmental, geographical, or biological reasons • 2 - Adaptation • Adapting to a new environment • Different foods? Predators? Climate? • 3 - Division • May become very different to the point of not being able to breed with the original species • Mating times, size considerations, food preferences, etc.

  10. p.116 Separation

  11. Adaptation

  12. Further Separation

  13. More Specific Adaptation

  14. Division

  15. Darwin’s Finches - Natural Selection? Maybe or Maybe not

  16. Final words on Speciation… • Many scientists view members of the same Genus to be genetically compatible species • In other words - THEY CAN INTERBREED WITH EACH OTHER. • Whether or not they do is the issue of speciation • Wolves can breed with Coyotes, but don’t. Why do you think?

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