Theme 3 Flashcards
What is Lamarck’s theory of evolution?
Species change over time
What is the “perfecting principle”?
When simple organisms evolve into more complex ones
Inheritance of Acquired Characteristics
Idea that changes an organism gains during its lifetime are passed onto offspring -> WRONG
Where did Darwin’s insights come from?
Geology and the fossil record, geographic distribution of species, and comparative morphology of species
Darwin realized that the geology of Earth changes slowly over time and that:
Fossils provided evidence that life did too
What is homology?
When the similarity present in a group of organisms to due to shared ancestry
Darwin’s General Theory
- Descent with modification
- Change in allele frequencies of populations over time
Biological Evolution
Any change in the inherited traits of a population that occurs from one generation to the next
Cuvier
- found that many species have gone extinct, he thought in floods -> number of species declining
- showed that large bones in USA belonged to extinct mastodon, not modern elephants
Lyell
- Landforms (mountains, valleys, etc.) were not fixed but changed slowly as a result of geological processes that can be observed today (not catastrophes)
- Earth was much older than the accepted age
Darwin’s Four Postulates
- Individuals within a species vary
- Some variation is passed to offspring (heritable)
- More offspring are produced than can survive and/or reproduce
- Survival and reproduction are not random, but related to phenotypic variation
Evolution in response to natural selection is inevitable if:
- There is variation in a trait
- Variation is heritable
- Some variants reproduce more than others (fitness)
- Specific features of the environment can generate natural selection on a trait
Natural Selection at Work
- Variation arises via mutations in genome
- Some variation confers a fitness advantage (e.g. non-synonymous mutations)
- Some variants produce more copies of themselves which all inherit the advantageous mutation(s) in their RNA
