Presentation is loading. Please wait.

Presentation is loading. Please wait.

Evolution by Natural Selection. Scientific Theory  An explanation of natural phenomenon supported by a large body of scientific evidence obtained from.

Similar presentations


Presentation on theme: "Evolution by Natural Selection. Scientific Theory  An explanation of natural phenomenon supported by a large body of scientific evidence obtained from."— Presentation transcript:

1 Evolution by Natural Selection

2 Scientific Theory  An explanation of natural phenomenon supported by a large body of scientific evidence obtained from many different investigations and observations.

3 Evolution  A gradual change in a species (populations) through adaptations over time.  Adaptation = some phenotypic feature or trait that improves an organism’s likelihood of survival and reproduction.  In Georgia, there is a popular hunting area of forest called the Poopycack forest, where the Poopy Deer lives. This species of deer has 6 ears.  How might this adaptation have occurred and how is it beneficial?  What would you expect to happen to the Poopy Deer population in the next 1000 years?  A gradual change in a species (populations) through adaptations over time.  Adaptation = some phenotypic feature or trait that improves an organism’s likelihood of survival and reproduction.  In Georgia, there is a popular hunting area of forest called the Poopycack forest, where the Poopy Deer lives. This species of deer has 6 ears.  How might this adaptation have occurred and how is it beneficial?  What would you expect to happen to the Poopy Deer population in the next 1000 years?

4 Charles Darwin “Theory of Evolution by Natural Selection”  Proposed that new species could develop through a process called Natural Selection  During his travels aboard HMS Beagle, made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time  Proposed that new species could develop through a process called Natural Selection  During his travels aboard HMS Beagle, made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time

5 Darwin’s Voyage Darwin studied animal species in the Galapagos Islands and found they each had unique adaptations

6 Darwin’s Studies  Galapagos finches demonstrate different adaptations to eat different kinds of foods  Galapagos tortoises are the biggest in the world

7 Natural Selection  Acts on Phenotype rather than Genotype  Those better suited for their environment will survive  Those least suited to their environment will die faster, leaving fewer offspring  Acts on Phenotype rather than Genotype  Those better suited for their environment will survive  Those least suited to their environment will die faster, leaving fewer offspring

8 Genetic variation is essential!  _________ promote genetic variation, which helps ensure a species survival  Like crossing over!  _________ promote genetic variation, which helps ensure a species survival  Like crossing over! Mutations

9 How does a great number of species ensure that at least some organisms survive major changes in the environment?  Those who are better at adapting will survive major changes in the environment

10 Natural Selection  A mechanism for change in a population  Natural Selection (NS) is responsible for most evolutionary change by selectively changing genetic variation through differentiated survival and reproduction.  Goal - To be fit enough to survive and reproduce  Three types of NS  A mechanism for change in a population  Natural Selection (NS) is responsible for most evolutionary change by selectively changing genetic variation through differentiated survival and reproduction.  Goal - To be fit enough to survive and reproduce  Three types of NS

11 Stabilizing Selection  Favors average individuals in a population  Those individuals have a “selective advantage”.  Reduces variation in a population  Favors average individuals in a population  Those individuals have a “selective advantage”.  Reduces variation in a population

12 Directional Selection  Favors one of the extreme variations of a trait  Can lead to rapid evolution of a population  Favors one of the extreme variations of a trait  Can lead to rapid evolution of a population

13 Disruptive Selection  Favors both extreme variations of a trait  Leads to evolution of two new species  Favors both extreme variations of a trait  Leads to evolution of two new species

14 Speciation  A process of producing two individual species from one  Members of the population no longer interbreed within their natural environment  A process of producing two individual species from one  Members of the population no longer interbreed within their natural environment

15 Evidence for Evolution:  1. Fossil record  A piece of organism or imprint left behind.  Fossils show that species have changed over time.  2. Vestigial structures  Body structures that have shrunken and are not used anymore.  3. Homologous structures  Structures that share a common ancestry and look/behave similarly.  4. Embryology  5. DNA homology, Amino Acid homology, Mitochondrial DNA, Photosynthetic Plant cells  1. Fossil record  A piece of organism or imprint left behind.  Fossils show that species have changed over time.  2. Vestigial structures  Body structures that have shrunken and are not used anymore.  3. Homologous structures  Structures that share a common ancestry and look/behave similarly.  4. Embryology  5. DNA homology, Amino Acid homology, Mitochondrial DNA, Photosynthetic Plant cells

16 Evidence For Evolution  Fossils  Provide a record of early life and evolutionary history  Fossils  Provide a record of early life and evolutionary history

17 Geologic Strata (sedimentary layers) and Carbon Dating  Carbon-14 (remember isotopes?)  Used to date any object composed of carbon  Radioactive carbon decays over time  check amount of C14 left in sample, enabling you to tell age of object  Carbon-14 (remember isotopes?)  Used to date any object composed of carbon  Radioactive carbon decays over time  check amount of C14 left in sample, enabling you to tell age of object Defining age of fossils!

18  Did you know that whales have feet?  Well, sort of….  Did you know that whales have feet?  Well, sort of….

19 Fossils help us determine whale evolution 60 million years ago 50 million years ago 40 million years ago Yesterday

20  Human tail-bone, wisdom teeth, appendix (they have no purpose)  Snake feet,  Whale feet  Human tail-bone, wisdom teeth, appendix (they have no purpose)  Snake feet,  Whale feet Vestigial Structures

21 Homologous Structures (derived from a common ancestral feature) Limb adapted to function means the same!

22 Analogous Structures- similar in function but not structure

23 Evidence For Evolution  Embryology  Similarities among the young embryos suggest evolution from a distant, common ancestor  Biochemistry  Comparing DNA and RNA  Embryology  Similarities among the young embryos suggest evolution from a distant, common ancestor  Biochemistry  Comparing DNA and RNA

24 How do we know what happened when?  Radiometric dating relies on half-life decay of radioactive elements to allow scientists to date rocks and materials directly  Stratiography provides a sequence of events from which relative dates can be extrapolated  Molecular Clocks allow scientists to use the amount of genetic divergence between organisms to extrapolate backwards to estimate dates.  Radiometric dating relies on half-life decay of radioactive elements to allow scientists to date rocks and materials directly  Stratiography provides a sequence of events from which relative dates can be extrapolated  Molecular Clocks allow scientists to use the amount of genetic divergence between organisms to extrapolate backwards to estimate dates.

25 DNA/Amino Acid Homology  Human 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A- A-C-T-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’  Whale 5’A-C-C-T-T-A-C-C-A-A-T-C-A-T-T-C-C-C-T-A- A-C-T-T-A-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’  Frog 5’A-C-C-A-T-G-C-G-T-G-T-C-A-T-C-C-C-C-G-A- G-C-T-T-C-G-G-T-A-T-T-A-C-G-C-A-A-G-C-3’  Gorilla 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A- A-C-A-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’  Human 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A- A-C-T-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’  Whale 5’A-C-C-T-T-A-C-C-A-A-T-C-A-T-T-C-C-C-T-A- A-C-T-T-A-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’  Frog 5’A-C-C-A-T-G-C-G-T-G-T-C-A-T-C-C-C-C-G-A- G-C-T-T-C-G-G-T-A-T-T-A-C-G-C-A-A-G-C-3’  Gorilla 5’A-T-C-T-T-A-C-G-A-A-T-C-A-T-G-C-C-C-T-A- A-C-A-T-C-G-G-C-A-T-T-A-C-G-C-T-A-G-C-3’ (Means the same!) Can you create a cladogram from the information above?

26  FsYmkeY


Download ppt "Evolution by Natural Selection. Scientific Theory  An explanation of natural phenomenon supported by a large body of scientific evidence obtained from."

Similar presentations


Ads by Google