Genetics and Evolution Notes

Genetics and Evolution

Mendel's work with pea plants:
- Focused on isolating alleles of genes.
- He was able to identify patterns of inheritance even without fully understanding the mechanisms at a molecular level.

Darwin's theory of evolution is supported by evidence from various scientific disciplines.
Repeated tests and observations consistently support the fundamental principles of evolution.
Classifications of animals may change with new molecular data but the underlying principles of evolution remain.

Biogeography: The study of the geographic distribution of species and their ancestors.
Fossil Records: The history of life preserved in rocks.
Anatomy: Comparing the structures of different organisms.
Embryology: Studying the development of organisms.
Molecular Evidence: Examining DNA and protein sequences.

Biogeography studies the distribution of species and the geography of where organisms and their ancestors lived.
Continental Drift and Pangaea:
- The concept of Pangaea, where all continents were once connected, is relevant.
- Fossil records and geographical features support the idea of matching continents.

Closely related species can exhibit differences due to divergent evolution.
Speciation: One species with a shared common ancestor evolves into different species.
Selective Pressure: Environmental factors drive variation within a species, leading to the formation of new species.
Barriers: Geographical or other barriers can lead to the divergence of species.

Distantly related organisms can independently evolve similar traits.
Similar Selective Pressures: Similar environmental conditions lead to similar adaptations in unrelated species.
Example: Ground-dwelling birds (ostrich, rhea, emu) in different continents have similar characteristics due to similar environments, despite geographical barriers preventing interbreeding.

Fossils are found in rock layers (strata).
Strata: Rock layers deposited sequentially from the bottom up.
Deeper layers contain older fossils.
Fossilization: It takes a long time.
The layering is similar to the stratification found in ancient civilizations.
Common Ancestors
- Common ancestors are found in deeper rock layers below their descendants.

Rocks form from the bottom up, allowing for relative dating.
Radioactive dating techniques allow for absolute dating of rocks.
Analogy: Stacking cups to illustrate how the bottom layer must be present before a top layer can form.

Example strata diagram:
- Six strata are shown in the example diagram.
- The fern (FEM) is the most recent organism to have evolved because it is in the top stratum.
- The trilobite is the most likely common ancestor because it is in the lowest stratum.
- The gastropod was around for the longest period of time as it is found in four of the six strata.

Fossil record shows the evolution of horses over time.
Changes in toe structure in horse legs:
- Early horses had multiple toes.
- Modern horses have a single toe (hoof).
- Multiple toes regressed and/or fused to evolve a single hoof.
Advantages of this change:
- It allowed for faster running.
- It provided foot protection.
- It increased stability.
Horse size increased over time, offering advantages such as:
- Increased strength.
- Improved intimidation.
- Better overall survival.

Arrangement: From primitive to more recent.
Example: Transition from marine to land environment.
Adaptations:
- Development of legs from fins (toes).
- Development of lungs from gills for breathing air instead of extracting oxygen from water.