1. Evolution
Biology 20

2. Six-Kingdom Systems of Classification
Monera
Monera

3. Phylogeny

4. Evidence of Evolution
Evolution: all changes that have occurred in living things since the beginning of life.

5. Life on Earth Compressed -1 Year
January 1st – Solar System and Earth Form
March 3rd – First Evolution of Life – Bacteria
October 21st – Eukaryotes Appear
November 18th – First Complex Multi-cellular Animals
November 28th - Plants and Arthropods Invade the Land
December 2nd - Vertebrates – Early Amphibians Invade Land
December 13th – Mammals and Dinosaurs Appear
December 26th – Dinosaurs Go Extinct
Dec 31st 4:40pm – First Human Ancestors Appear
Dec 31st 11:48pm – First Modern Humans Appear
Dec 31st 11:59pm – Start of Recorded History – Agriculture
Dec 31st 11:59:59 – Modern History of the understanding of the Earth – Geology and Palaeontology Founded

7. Geological Ages
We can divide the history of life on Earth into 4 main stages:
-Precambrian: From the formation of the Earth to 550 million years ago the origin of life, bacteria.
- No oxygen in the atmosphere.
- Oxygen appears in atmosphere (2 billion yrs ago) to present level 21%.
- Eukaryotes appear. No hard parts: bone, teeth, shells, so few fossils.
-Paleozoic Era to 250 million years ago. Fossils appear, complex multicellular organisms, invasion of the land by plants and animals.
-Mesozoic Era to 65 million years ago. Appearance of mammals and flowering plants, but the land is dominated by dinosaurs (reptiles).
-Cenozoic Era. 65 million years ago until present. Land dominated by mammals and flowering plants.

8. Some Major Mileposts of Life

9. Fossil Evidence
Fossils are remains, traces or other direct evidence of past life forms
Most fossils form from the burial of plants and animals in the sediment
Most fossils are embedded in sedimentary rock

10. Body Fossils
1. Body Fossils are the actual body or body parts of an organism that has been preserved. These fossils may or may not be altered (fossils that have gone through a chemical change or physical change). The two main types of body fossils are (A) unaltered remains and (B) altered remains…
(gastropod)
A. Unaltered remains of fossils means that the remains have gone through little or no chemical or physical change.

11. (saber-toothed cat skull)
(This mammoth died in ice 39,000 years ago)
(saber-toothed cat skull)

12. Body Fossils B. Altered remains
- Recrystallization: means that there is a chemical change of the atoms that make up the hard parts of the organism. In this ammonite, the hard parts have been changed to Calcite, a mineral.

13. Trace Fossils
2. Trace Fossils are not the actual body or body parts of life that has been preserved. These fossils show how an organism lived, how it moved, what its feet looked like, how it raised its offspring (its children), what it ate and what its shape was.
(gastropod cast)
Track trail tube burrow nest eggs, life activities

14. This worm tube trace fossil is hollow (the hole goes all the way through it).
(Dinosaur tracks)
Do you see the people?
Coprolite:

15. Fossil Record
Paleontologists study the fossil record based on the boundaries between the strata, this helps determine the relative age of fossils
Fossil links combined with modern comparative anatomy allows us to deduce vertebrate descent:
Fish  amphibians  reptiles  birds and mammals

16. Evolution of the Modern Horse
One of the few animals for which we have a fairly complete evolutionary record is the horse, as all the main stages of horse evolution have been preserved in fossil form. Over 60 million years the horse evolved from a dog-sized rainforest-dwelling creature, into an animal adapted to plains-dwelling and standing up to 2 metres high.
In the process it traded-in its multi-toed feet, adapted for walking across the forest floor, for single-toed hooves, suited for running over open country.

17. Geological Time Scale
Geological history of Earth is divided into eras and periods
Fossil record provided relative dating of rock layers; top layer of rocks are younger than lower layers of rock
Absolute dating methods uses radioactive isotopes
Isotopes each have particular half-life or time it takes for half of the isotopes to decay and become non-radioactive
Carbon 14 is used to date organic matter; half decays to nitrogen 14 each 5730 year; limited to about last 50,000 years.

18. Mass Extinctions
Extinction is death of all members of a species in wild; mass extinctions are extinctions of many species in a short time.
Five mass extinctions in the fossil record
Following extinctions, remaining groups expand to fill habitats vacated by extinct species

19. Proposed that most mass extinctions are caused by asteroid impact
Impact of the asteroid would create climate similar to a nuclear winter with worldwide cooling (ice age)
Cretaceous-Tertiary( million years ago) border has a higher level of iridium, rare in the Earth’s crust but common in meteorites
Huge meteorite crater of correct age ground in Caribbean Ocean and Yucatan peninsula; suspected sight of impact of meteor that results in dinosaur extinction
Marine animals fossil record indicates mass extinction occurs every 26 millions year; corresponds to movements of solar system within the Milky Way galaxy.
Craters

20. Biogeographical Evidence
Biogeography is the study of distribution of plants and animals throughout the world
Current distribution of organisms reflects the evolutionary history, organisms evolve in one location and spread out into other regions; for example, no rabbits are found in South America – they originated elsewhere and did not reach South America

21. Physical factors, including locations of continents, limit population ranges
Continental drift states that continents have slowly moved over time
Explains close puzzle-piece fit of east coast of South America with west coast of Africa, and other continent edges
Explains distribution of seed ferns throughout southern continents
Explains distribution of early reptiles across many continents from time when land was joined
Explains divided distribution of mammals that evolved after continents parted.

22. Movement of the Continents

23. Anatomical Evidence
Many organisms share a unity of plan, for example, the vertebrate forelimbs contain same sets of bones used for different functions in bat wings, whale fins, etc
Simplest explanation in having a common ancestor whose basic forelimb plan was modified in succeeding groups as each continued along it own evolutionary pathway.
Homologous structures are similar in structure derived through descent from a common ancestor
Analogous structures have similar functions but differ in anatomy and did not derive from the same ancestral structure; for instance, an insect wing and a bird wing

24. Homologous and Analogous Structures

25. Embryological Development
All vertebrates have a tail, notochord and pharyngeal pouches during development
In humans
The notochord develops into the vertebral column
The tail becomes the sacral vertebrae (tailbone)
The pharyngeal pouches become the Eustachian tubes, middle ear and thyroid gland
Simplest explanation is that the notochord and pouches are primitive fish features and fish are ancestral to other vertebrates

26. Comparative Embryology

27. Biochemical Evidence
Almost all living organisms use the same basic biochemical: DNA, ATP, many identical enzymes, DNA triplet codes and 20 amino acids
Similarity of biochemistry is explained by descent from a common ancestor
DNA base sequences differences is DNA between a number of organisms shows less difference the more closely related they are; for example, 2.5% difference between humans and chimpanzees but 42% difference between humans and lemurs.

28. Contributors to the Theory of Evolution
Linneaus
Developed the classification system (binomial nomenclature)
Linneaus did not believe in evolution, but his classification system helped to organize many organisms to show similar ancestry
Buffon
Anticipated many of Darwin’s ideas
Extreme conflict with the church

29. Other Contributors to the Theory of Evolution
Cuvier
Founder of paleontology
Also did not believe in evolution, but did lay the ground work for Darwin’s theory
Lyell
Geologist
Proposed the Earth is always changing and is very old

30. Another contributor Larmark Recorded the first theory of evolution
Two major disputable points:
Nature has an innate tendency to evolve in the direction of increasing complexity, determined by the interaction with environment
Acquired characteristics will
be passed onto offspring
(not genetically acquired)

31. Modern Evolutionists Charles Darwin Studied medicine and theology
At 22 became a naturalist on the HMS Beagle which sailed through the Galapagos Islands
Proposed the Theory of Natural Selection
Alfred Wallace
Proposed the same idea as Darwim

32. Theory of Natural Selection
Natural selection is a theory that proposes that individuals whose genetic variation best adapt them to their environments will be most likely to survive and pass on those traits.

33. Darwin’s Discovery of the Theory of Natural Selection
(Fact 1) There is a potentially exponential increases in population  Overpopulation +
(Fact 2) Population sizes are relatively stable (observation)
(Fact 3) Resources are limited =
(Inference 1) There is a struggle for existence

34. Darwin’s Discovery of the Theory of Natural Selection
(Fact 4) Individuals are unique (observation)  Variation +
(Fact 5) Many characteristics are inherited =
(Inference 2) There is a differential survival, that is natural selection Survival of the Fittest
(Fact 6) The Earth is very old
(Inference 3) Through many generations species evolve  Origin of species by inheritance of successful variation

35. Key Points of Natural Selection
Individual differences are essential for evolution
The struggle in nature that is of greatest consequence to evolution is not that between different species; rather, it is the competition within a population of a single species to obtain food, attract a mate, escape predators, etc.
Only the difference that are inherited are relevant to evolution
Evolution generally takes a great deal of time and is ongoing.

36. Sources of Variation
Mutation create the variation necessary for Natural Selection
Mutations are random changes in the DNA sequence in a chromosome
Caused by environmental factors (chemical, radiation or viruses) or in errors when the cell makes copies of the DNA
Only the mutation to the chromosomes in the sex cells are passed to the next generation.
Mutations can be harmful, neutral or beneficial. (most are harmful or neutral)

37. Sexual Reproduction and Variability
Asexual Reproduction = no variation
Sexual Reproduction = variation
In sexual reproduction there are two parents and the offspring inherit a copy of each gene from each parent
The chromosomes are assorted randomly. So each sex cell has a different combination of chromosomes.
Sexually reproducing species choose different mates.

38. Speciation
Species – a group of organisms that look alike and can interbreed under natural conditions to produce fertile offspring.
Speciation – the creation of a new species
Allopatric Speciation – speciation by geographic then reproductive isolation.

39. Geographical Isolation
Species become geographically isolated by some physical barrier. A mutation occurs in one group that does not occur in the other.
Natural selection takes place and the populations evolve independently.
In time, the changes that occur between the species are so pronounced that if the were reunited they can no longer mate.