1. Evolution and the History of Life Part 1
Mr. Tsigaridis
Evolution and the History of Life Part 1

2. Change Over Time Differences Among Organisms
Do Species Change Over Time
Evidence of Evolution: The Fossil Record
Fossils
Reading the Fossil Record
Gaps in the Fossil Record
Vestigial Structures
Case Study: Evolution of the Whale
Evidence of Evolution: Comparing Organisms
Comparing Skeletal Structures
Comparing DNA from Different Species
Comparing Embryonic Structures

3. Changes Over Time Differences between species relate to adaptations.
Adaptations – a hereditary characteristic (attribute) that helps an organism survive and reproduce in its environment.
Physical adaptations are heredity. Which means that the organism has no choice about the characteristics.
Emotional, cultural, and behavioral adaptations are choices that humans can make.

4. = + It’s all about Species Horses and Donkeys are separate species
What is a Species?
A population of organisms that can mate with one another produces fertile offspring.
Example: Horses, Donkeys, and Mules
Breeding a male donkey to a female horse results in a mule;
Breeding a male horse to a female donkey produces a hinny = +
Sterile Mule
Horses and Donkeys are separate species

5. Do Species Change Over Time
The Earth is very old – 4.6 Billion Years
The Earth was formed approx. 4.6 bya
The oldest rock is 3.5 Billion years
Fossil evidence suggests that species have changed over time because younger fossils are different, yet similar to older fossils.

6. Evolution
Evolution is the process by which populations of organisms acquire and pass on unique traits from generation to generation, affecting the overall makeup of the population and potentially leading to new species.

7. 4. selection (natural and “artificial”)
Four distinct mechanisms generate evolution (change in allelic frequency in populations over time):
1. mutation
2. gene flow
3. genetic drift
4. selection (natural and “artificial”)

8. Gene flow = movement of alleles from one population to another, which may change the allele frequencies
Gene flow can happen in several ways; in reality, usually a combination of them
individuals leave a population, taking their alleles with them
individuals join a population, introducing new alleles (or more copies of ones already present)
individuals in the population mate with outsiders, but the offspring stay in the population
this introduces new alleles (or additional copies of ones already present), because half of the offspring's alleles are from the outsider

9. Gene flow essentially moves alleles between populations
this tends to make neighboring populations similar to each other
because they exchange alleles and individuals in each have ancestors from the other
gene flow can take a mutation in one population and spread it throughout the world

10. Gene Flow
the more migration or interbreeding occurs between two population, the more rapidly they become similar
gene flow is important because it explains how a species like humans can be essentially the same all around the world

11. Genetic Drift
Genetic drift = change in allele frequencies due to chance
how it works
in any random process, like flipping a coin, we can predict the odds of any given outcome, but we can't predict which specific outcome will occur in any given case
Genetic Drift has a greater effect on smaller populations than larger populations.

12. In large populations, drift will not have much effect
just as when you flip a coin 1000 times, you expect to get fairly close to 500 heads
but the smaller the population, the more this random sampling error will change allele frequencies every generation
just as when you flip a coin only 4 times, you are not surprised at all to get 75% heads, or even 100% heads

13. Geologic Time Notations
ya – Years Ago mya – Million of years ago bya – Billion years ago Precambrian Paleozoic ERA Mesozoic ERA Cenozoic ERA

14. Era word roots Geologist use the clues in some of these words.
For example:
zoic refers to animal life
paleo means ancient
meso means middle,
ceno means recent.
So the relative order of the three youngest eras, first Paleoozoic, then Mesozoic, then Cenoozoic, is straightforward.

15. Evidence of Evolution: The Fossil Record
Fossils
Reading the Fossil Record
Gaps in the Fossil Record
Vestigial Structures

16. Fossils
Are found in the earth’s crust – the very uppermost part of the earth that is exposed to the surface or lying immediately below the oceans.

17. The Best Crust for Fossils
Sedimentary Rocks are the best crust for fossil formations;
Example: The Grand Canyon. Strata = Layers of sediment so its called sedimentary rock

18. Rocks contain clues to the Earth’s past.

19. What are Fossils
Fossils are the mineralized remains of animals or plants or other traces such as footprints.
All of the fossils and their placement in rock formations and sedimentary layers (strata) is known as the fossil record.
The study of fossils is called paleontology.

21. What kind of rock is this?
Sedimentary Rock

22. Law of Superposition:Youngest on Top
An undeformed sedimentary rock layer is older than the layers above it and younger than the layers below it D C B A

23. Law of Superposition D C B A In terms of Relative Age
Rock Layer B must be younger than Rock Layer A
but
Rock Layer B is older than Rock Layers C and D. D C B A

24. Once the order of formation is known, a RELATIVE AGE can be determined for each rock layer

25. Gaps in the Fossil Record
Occur because specific conditions are needed for fossils to form
Organisms with hard body parts (skeletons) are more likely to form fossils than organisms with soft body parts. Basic to this is the organisms cannot be eaten before fossilization
Find shells and bones
Fossils form best without oxygen – why peat bogs and tar pits have great fossils. Burial by sediments reduce oxygen exposure.
Freezing also allows fossil formation – Mammoth that Japanese scientists are trying to clone from DNA extracted from frozen Mammoth fossil.
Fossils once formed must not be destroyed.

26. Sea shells embedded in marine rock near Santa Cruz
Ammonites near Redding

27. Human Remains

28. Vestigial Structures Mammals are warm blooded vertebrates
Vestigial structures are organs that have no apparent function.
Examples:
Human appendix – narrow tube attached to the large intestines
Chimpanzee, gorilla, and orangutan appendix is functional and used to help digest tough plant material

29. Appendix

30. Whale evolution (terrestrial to aquatic in ~ 8 Myr)
8 million years total

31. PBS Whale Evolution
One structural remnant (remaining part) of this evolutionary process are hind limb bones. These bones are called vestigial structures.

32. Evidence of Evolution: Comparing Organisms
Comparing Skeletal Structures
Comparing DNA from Different Species
Comparing Embryonic Structures

33. Comparing Skeletal Structures
Homologous Structures
Having similar origins and anatomical patterns
Examples – bird wings, human arms, whale flippers, bat wings, cat legs.

34. Homologous Structures

35. Analogous Structures
Analogous structures do the same thing – similar function, but different anatomy.
Wings (butterfly external skeleton, bat internal skeleton
Analogous structures: wing of an insect, bird, bat and pterosaur

36. Comparing DNA from Different Species
The actual molecular characteristics of DNA is measured and compared to other organisms.
There are four different nucleotides in DNA (Adenine, Guanine, Cytosine, and Thymine).
Gene sequencing – sections of DNA are sequenced for the order of nucleotide bases (ATCG or ATGC or ACTG, etc).

39. What We've Learned So Far
By the Numbers: What Does the Draft Human Genome Sequence Tell Us?
The human genome contains million chemical nucleotide bases (A, C, T, and G).
The average gene consists of 3000 bases, but sizes vary greatly, with the largest known human gene being dystrophin at 2.4 million bases.
The total number of genes is estimated at 30,000 — much lower than previous estimates of 80,000 to 140,000.
Almost all (99.9%) nucleotide bases are exactly the same in all people.
The functions are unknown for over 50% of discovered genes.
The dystrophin protein plays an important structural role as part of a large complex in muscle fiber membranes.  When dystrophin is missing or non-functional, the entire complex is compromised, leading to degeneration of muscle tissue.  When the ability to regenerate the muscle is exhausted, muscle wasting occurs resulting in     Muscular dystrophy

40. Looking for Relatedness

41. Crime Solving:
The COmbined DNA Index System, CODIS, blends computer and DNA technologies into a tool for fighting violent crime.

42. Comparing Embryonic Structures
Ontogeny: Development of the Individual from conception to death.
Phylogeny: Development of the Species.
Vertebrate organisms (those having a backbone) have similar stages of life as an embryo

43. Open Court Publishing Company