1. Evolution Natural Selection Classification

2. How Life Came to Be
With all this talk on genetics…how did we get to who we are today?
First belief – SPONTANEOUS GENERATION!

3. Not So Much…(Biochemical Evidence)
After the 1800’s….two ideas came about:
Abiogenesis: the idea that the first cells that grew on Earth came from inorganic matter.
Biogenesis: the idea that life evolved from life
– the first cells that grew on Earth came from other cells.

4. Abiogenesis Ideas
Abiogenesis: the idea that the first cells that grew on Earth came from inorganic matter.
Macromolecules developed from a pool of molecules
To prove this….Miller-Urey Experiment: simulated an Early Earth environment proving life came from space

5. Miller-Urey Experiment

6. Miller-Urey Experiment
Early Earth was a hot, violent planet
Many lightning storms and boiling oceans
Atmosphere contained hydrogen, ammonia, methane, and carbon dioxide – would kill us.
The molecules they collected were all organic molecules!

7. Biogenesis Ideas
Biogenesis: the idea that life evolved from life, proven today through DNA
Francisco Redi Experiment – placed rotting meat in glass jars (some jars closed, some not). Fruit fly maggots only grew on the jars that were not covered. The covered jars had no signs of life.

8. Francisco Redi Experiment

9. Biogenesis Ideas
Louis Pasteur Experiment – showed that microorganisms would grow in a flask only if they could move up the neck of the beaker and get inside. Proved bacteria didn’t arise from broth, but arose from other bacteria cells

10. Louis Pasteur Experiment

11. How Life Grew (Fossil Evidence)
First cells – Prokaryotic Cells 3.5 billion years ago (Survived with no oxygen and ate macromolecules)
#2– Prokaryotic Cells that used oxygen and ate through photosynthesis
#3– Eukaryotic Cells 2.1 billion years ago
Multicellular Organisms – 1.5 billion years ago
Invertebrates – 500 million years ago
Marine Life – 470 million years ago

12. Observing Organisms
Homologous Structures – anatomical structures that have the same evolutionary origin (ex. Whale fin bones look like human arm bones)
Vestigial Structures - anatomical structures that have no present use (ex. Wisdom teeth)

13. Homologous Structures

14. Embryological Structures
Embryology shows the similarities in the structures of vertebrate embryos.

15. Natural Selection
The difference in survival and reproduction rates of the population depending on how well adapted they are to their environment.
SURVIVAL OF THE FITTEST!
Adaptations – physical, behavioral, or chemical change that gives and organism an advantage to survive

16. How Natural Selection Works
1. Organisms produce many more offspring than survive – think about how all the acorns fall off the trees – does every single acorn become a tree?
2. Variations exist in populations – not all members of a population are the same…think about how not every human looks exactly alike.

17. How Natural Selection Works
3. There is competition for survival – survival of the fittest
4. Successful organisms are those that reproduce and pass on the traits - successful organisms pass on the successful traits
5. Organisms adapt to their environment – variation in genes – some species have more genes than others (genetic diversity).

18. Speciation
The creation of new species – a slow process that can take many generations and may not be observed in our human lifetime.
Population of breeding organisms is separated from one to another – geographic isolation
Groups can no longer mate with each other – reproductive isolation

20. Disease Influencing Natural Selection
Bacteria become resistant to antibiotics
Insects become resistant to pesticides
This causes the inability to kill off harmful bacteria and insects.
What affect could this have on our current human population today?

21. Classification
Now we know how to observe organisms, how do we group them and name them?
Classification - grouping things based on shared characteristics
The science way of grouping organisms is called Taxonomy – grouping organisms based on shared characteristics
Taxonomy is based on Phylogeny – the evolutionary history of an organism

22. Taxonomy
Always remember that related organisms have similar DNA – therefore similar amino acids
Taxonomic groups range from a large group or organisms called Kingdoms to small groups of organisms called Species.
Species group together the most genetically similar organisms where as Kingdoms contain the broadest group of organisms

24. How to Name an Organism
Binomial Nomenclature – a two word scientific Latin naming system to name each species.
The two-word formula is first Genus then Species.
Genus always comes first, and starts with a capital letter. Species always comes second and always starts with a lower case letter. They are also always italicized.
For example, Humans are considered Homo sapiens.

25. Organism Naming What if we don’t know what the organism is?
We use a Dichotomous Key!
The key uses the same scientific naming system to help us identify an unknown organism.
The key has a series of choices (the organism’s characteristics) that leads the user to the correct scientific name.

27. Phylogenetic Tree
Once we know the organism’s name and what their traits are, we can create an evolutionary tree to show the similarities and differences between groups of organisms.
A Phylogenetic Tree is an evolutionary branch of a group of organisms.
The traits that evolve early in time are at the bottom part of the branch and the traits that evolved later in time are at the top of the branch.

28. Cladogram
To show the tree, we use an image called a Cladogram – the diagram that shows the relationships between organisms.

29. Who is most closely related to organism 1?
Evolved Last
Most
Closely
Related
Evolved Early
Who is most closely related to organism 1?
Who is least closely related to organism 1?

30. History of Classification
A Classification System dates all the way back to Aristotle in Greece - only thought there were two Kingdoms – non-motile (plants) and motile (animals)
Thomas Whittaker brought the major breakthrough in thought there were five Kingdoms (plants, animals, bacteria, protista, and fungi)
Scientists most recently discovered (with DNA technology) that there is a large difference between Eubacteria and Archeabacteria (not really bacteria at all, just Archea) and thus created the current six Kingdom system.