1. Data Driven Process Supported by Evidence
Theory of Evolution
Data Driven Process Supported by Evidence

2. TEKS
(7) The student knows evolutionary theory is a scientific explanation for the unity and diversity of life. The student is expected to:
(A)  analyze and evaluate how evidence of common ancestry among groups is provided by the fossil record, biogeography, and homologies, including anatomical, molecular, and developmental;
(B)  analyze and evaluate scientific explanations concerning any data of sudden appearance, stasis, and sequential nature of groups in the fossil record;

3. Vocabulary Evolution Ancestor Developmental homology Descended
Analogous Structure
Ancestor
Developmental homology
Descended
Embryology
Molecular homology
Offspring
DNA sequence
Fossil record
Genome map
Biogeography
Phylogenetic
Radioactive dating
Native
Homology
Genus
Anatomical homology
Species
Homologous Structure

4. What defines a Theory?
The term ‘theory’ when used in science does NOT mean guess, educated or otherwise.
In science:
Theory – a logically connected group of ideas that explain a set of facts or phenomena in the natural world which can be repeatedly confirmed through experimentation or observation.

5. Darwin’s Theory of Evolution by Natural Selection
A species, not an individual, that has changed over time and has members related through decent from a common ancestor.
(A species is a group of individuals who are genetically similar enough to reproduce with each other)
The change in the species’ population is driven by Natural Selection.
Natural Selection is the ability of the natural world to apply pressure/stresses to a population, and only those with beneficial traits will survive to reproduce (and pass on favorable traits to the next generation).

6. Evidence for the relatedness of life…
Hypothesis: All living species have descended from common ancestor(s) and changed over time.
Prediction: There should be evidence that shows the relatedness of species
Geographic distribution/Fossil record
Homologies

7. Fossil Evidence Fossils are preserved evidence of an organism.
There are basically 5 types of fossil evidence:
Mold-and-cast – bones or shells dissolve and leave a depression
Trace – impressions of movement (footprint, burrows, toothmarks, etc)
Body – entire body is preserved
Compression – organism is compressed and leave a dark imprint.
Petrification – minerals replace organic matter

8. How is a fossil evidence?
Fossils can tell us about time sequences. When used with radioactive dating of the rocks fossils are found in, paleontologists can create a timeline according to the fossil’s age, they show successive Evolutionary Change.
Fossil intermediates are transitional fossils that have been found between amphibians/reptiles, reptiles/birds, and reptiles/mammals

9. Evolution of horses as an example
Horse fore limb fossils have been well documented to show evolutionary connections to modern horses.

10. The fossil record is Incomplete
During Charles Darwin’s studies, the fossil record was VERY piece mail. Since the 1800’s many more fossils have been found making connects, but it is far from complete.
Reasons:
Soft tissues are rarely preserved
Tectonic movement of Earth’s crust has destroyed man fossils.
Fossilization only takes place in certain types of environments.
Paleontologists have not dug up every place on earth.
The fossil record does not show gradual change, it shows sudden appearances followed by stasis.

11. Homologous Evidence Homologies are similarities in structures.
There are 3 main types of homologies:
Anatomical
Developmental
Molecular

12. Anatomical Homologies
Comparing structures between organisms.
Homologous structures – same structure, different function (ex: the forelimbs of animals)

13. Anatomical Homologies
Comparing structures between organisms.
Analogous structures – different structure, same function (ex: wings of birds, bats, butterflies, etc)

14. Homology vs. Analogy
Natural selection appears to have favored similar adaptations in unrelated organisms in similar environments  these structures are analogous.
Flight is a good adaptation to have, so wings evolved in many different animal lines independently of each other.

15. Vestigial Structures
A feature or trait that exists, but has not apparent function. (ex: hindlimb bones in whales)

16. Vestigial Structures in Humans
Some examples in humans: Wisdom teeth, appendix and tailbone.
Wisdom Teeth
Tailbone
Appendix

17. Developmental Homologies
Embryology – the study of how related organisms tend to develop in very predictable stages.

18. Dog Fetus
Bat Fetus
Human Fetus

19. Molecular Homologies
The best evidence of evolution is coming from today’s ability to map genomes and compare gene sequences.
All living organisms share the same genetic code, DNA.

20. What similarities exist between humans and other animals?
Chromosomes and gene similarities between species show evolutionary similarities.
Human chromosome 2
Telomere sequences
Centromere sequences
Chimpanzee chromosomes 12
Telomere-like sequences
Centromere-like sequences
Human chromosome 16 13
(a) Human and chimpanzee chromosomes
(b) Human and mouse chromosomes 7 8 16 17
Mouse chromosomes

21. Cytochrome C protein similarities
Cytochrome C is a protein found in the inner membrane of the mitochondria.
It is understood that all organisms on the planet decended from prokaryotes.
If the prokaryotic DNA is not mutated much then connections can be made to the evolution of organisms.