Week 9 & 10 Flashcards
What are different evidence for evolution?
- Fossil record
- Embryologie
- ‘’Artificial’’ selection
- Biogeography
- Homology (physical & behavioral)
- Vestigials
Fossil Records (oldest to recent & it consequences)
Oldest to recent:
Shelled Invertebrates, Fish, Amphibians, Reptiles, Mammals, Birds, Man.
The theory was that we were all fish before. Amphibians were the first organism that went toward the land.
Based on a tree (go see power point), different species (allosaurus, archaeopteryx and crow) all shared a common ancestor (dinosaur). This is why birds still have bones of hands.
Embryologie
Early embryos are very similar, even when adults forms are very different.
Embryos belonging to the same ‘’group’’ (e.g. mammals) all have Gill Slits and tails. However some (like humans) might lose them.
The fact that embryos from different species are most similar in early stages of development may be explained by the fact that they share a common ancestor.
Evolutionary hypothesis: Lamarck - Inheritance of acquired characteristics
- Organisms tend toward perfection or greater complexity.
- Organisms use or disuse parts of their bodies to better use available resources.
- Acquired traits are passed down from parents to their offspring.
Exemple: Giraffe (became taller and their neck stretched)
What is evolution?
Evolution is the change in the characteristics of a species over several generation ms and relies on the process of natural selection.
The theory of evolution is that all species are related and gradually change over time.
Geology: Hutton and Lyell and The theories of geological change
- Earth is really old
- Process that changed Earth in past still occurring in present
Theories of geological change:
- Catastrophism (theory that Earth’s features are mostly accounted by violence/giant natural disaster)
- Gradualism (some mountains are higher than others/transition between states are not continual)
- Uniformitarianism (stacking up of different generation/gradual processes that occurred over long period of time)
“Artificial” Selection and exemple
- Individuals with desirable characteristics are selected (by humans) and allowed to reproduce
- Process repeated over several generation —> change in characteristics of (selected) population
Exemple: Darwin’s pigeon
What is Natural selection
- Mutation that arise at random
- The environnement selects it
Biogeography and 2 examples
It came from one and then new ones were created.
They became different by being in a different environment and their different prays and preditors.
Example: Four mockingbird species found in the Galápagos Islands
Example: Tortoise in wet environment and tortoise in dry environment.
Homology and examples
Common ancestral structure (Same origin) Different ecological conditions -> Divergent evolution (different selective pressures due to our environment) -> (different functions)
It is a divergent evolution
⭐️Similar structure/Different function
Example: Different wings and arm for animals
Example: Human and chimpanzee (physical) (behavioral - their laugh, smile, etc)
Example: Vestigial (left overs) structures and functions (snakes with tiny legs, etc)
- Common language: Nucleic Acids & Proteins
- Genetic information passed on to offspring
- Similarity: Common ancestor
- Differences: Mutations and divergence
- Evolutionary distance: more similar DNA/Protein sequences (more recent common ancestor)
Analogy and a example
- Different ancestral structure (different origin)
- Similar ecological conditions —> Convergent Evolution (they have the same parent, but they need the same thing so they will convert)
- Similar selective pressures (they live in the same environment) —> same functions
⭐️Different structure/Similar function
(Because they are in the same environment)
Example: Similar shape of bird arms, since they all need to swim since they live underwater
Divergent three exemples
- Birds of the Galápagos Islands
- Evolution of locomotion in mammals
- Evolution of leaves in plants
Convergent three examples
- Streamlined body: Adaptation to life underwater
- Adaptation to flight: Wings
- Niche of Placental and Australian Marsuplais
