1. Natural Selection Or, how did we get here….

3. Key concepts: Communicate scientific understandings using descriptions, explanations, and models Explain why variation within a population can enhance the chances for group survival Analyze how structural behavioral, and physiological adaptations within a population enable it to survive in a given environment

4. Key Vocabulary: Species Population Adaptation Natural selection Selective Breeding

5. Time out for vocabulary: Natural selection: the process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do Adaptation: a characteristic that improves an individual’s ability to survive and reproduce in a particular environment Species: a group of organisms that are closely related and can mate to produce fertile offspring Population: group of individuals of the same species in the same place

6. Natural Selection  The Theory of Natural Selection is so simple that anyone can misunderstand it…. (Anonymous)  Charles Darwin (1809-1882) saw three problems in need of a solution.  Darwin was not the only one to see these problems BTW  Other ‘Naturalists’ were struggling with the same issues  The Theory of Natural Selection is so simple that anyone can misunderstand it…. (Anonymous)  Charles Darwin (1809-1882) saw three problems in need of a solution.  Darwin was not the only one to see these problems BTW  Other ‘Naturalists’ were struggling with the same issues

7. Problem the First  There is change over time in the flora and fauna of the Earth  What we would commonly call ‘evolution’ today  The fossil record showed this to be pretty clear, even to people in the mid 1800s  This was not controversial in Darwin’s time, and is not now.  There is change over time in the flora and fauna of the Earth  What we would commonly call ‘evolution’ today  The fossil record showed this to be pretty clear, even to people in the mid 1800s  This was not controversial in Darwin’s time, and is not now.

8. The Second Problem  There is a taxonomic relationship among living things  People were big into classifying stuff  It was pretty obvious that there was a relationship between different species  Different birds, different grasses, different cats etc  There is a taxonomic relationship among living things  People were big into classifying stuff  It was pretty obvious that there was a relationship between different species  Different birds, different grasses, different cats etc

9. The Third Problem  Adaptation  Different kinds of teeth for different animals, say carnivore ripping teeth and herbivore grinding teeth  Different tissues within species  Heart vs. eye etc.  Adaptation  Different kinds of teeth for different animals, say carnivore ripping teeth and herbivore grinding teeth  Different tissues within species  Heart vs. eye etc.

10. The Solution!  Natural Selection provides a mechanistic account of how these things occurred and shows how they are intimately related.  It is one of those ‘oh man is that ever easy, why didn’t I think of that?’ type things.  Natural Selection provides a mechanistic account of how these things occurred and shows how they are intimately related.  It is one of those ‘oh man is that ever easy, why didn’t I think of that?’ type things.

11. How’s it work?  There is competition among living things  More are born or hatched or whatever, than survive and reproduce  Reproduction occurs with variation  This variation is heritable  Remember, there was NO genetics back then, Chuck knew, he just knew….  Realized that is wasn’t ‘blending’  There is competition among living things  More are born or hatched or whatever, than survive and reproduce  Reproduction occurs with variation  This variation is heritable  Remember, there was NO genetics back then, Chuck knew, he just knew….  Realized that is wasn’t ‘blending’

12. How’s it Work?  Selection Determines which individuals enter the adult breeding population  This selection is done by the environment  Those which are best suited reproduce  They pass these well suited characteristics on to their young  Selection Determines which individuals enter the adult breeding population  This selection is done by the environment  Those which are best suited reproduce  They pass these well suited characteristics on to their young

13. Parts:

14. How’s it Work?  REPRODUCTION is the key, not merely survival  If you survive to be 128 but have no kids, you are not doing as well as I am  Say that I, I have reproduced…  Assuming the traits that made me successful will help them then I amore fit NOW than the 127 year old guy  REPRODUCTION is the key, not merely survival  If you survive to be 128 but have no kids, you are not doing as well as I am  Say that I, I have reproduced…  Assuming the traits that made me successful will help them then I amore fit NOW than the 127 year old guy

15. This lecture keeps evolving…..  Survival of the Fittest (which Chucky D NEVER said) means those who have the most offspring that reproduce  So, the answer to the trilogy of problems is:  ‘Descent with modification from a common ancestor, NOT random modification, but, modification shaped by natural selection’  Survival of the Fittest (which Chucky D NEVER said) means those who have the most offspring that reproduce  So, the answer to the trilogy of problems is:  ‘Descent with modification from a common ancestor, NOT random modification, but, modification shaped by natural selection’

16. SOOOOOO…what does it mean…  Evolution is a change over time in a population of organisms…they have to reproduce in order to pass the traits…  Turn to page 115--Insects  Evolution is a change over time in a population of organisms…they have to reproduce in order to pass the traits…  Turn to page 115--Insects

17. Human intervention:  Dog breeds…how did we do it?  Breed dogs of certain qualities with other dogs with traits we wanted…  Continued to do this and we get a dog that we want.  Dog breeds…how did we do it?  Breed dogs of certain qualities with other dogs with traits we wanted…  Continued to do this and we get a dog that we want.

18. What does this mean:  Our traits will change over time in order to BETTER adapt to what is going on in our environment  This can lead to changes in species and even the making of a new species…  Our traits will change over time in order to BETTER adapt to what is going on in our environment  This can lead to changes in species and even the making of a new species…

19. Different types of selection  Directional Selection  What most of us think about when we think about selection  An extreme value is selected for  Human brain size is a nice example  Directional Selection  What most of us think about when we think about selection  An extreme value is selected for  Human brain size is a nice example

20. Different kinds of selection  Stabilizing or Normalizing selection  The middle is selected for  Many examples here  Symmetry  Two eyes  Stabilizing or Normalizing selection  The middle is selected for  Many examples here  Symmetry  Two eyes

21. Different kinds of selection  Disruptive selection  Extremes are selected for  Might be where the two sexes come from  Trait was probably gamete sized  Two ‘mating types’  Disruptive selection  Extremes are selected for  Might be where the two sexes come from  Trait was probably gamete sized  Two ‘mating types’

22. What does it all mean?  Evolution is driven by NATURAL selection.  What did your moth simulation tell you?