Evolution Flashcards
What is the definition of evolution?
A change in biological entities over time (over generations)
What was the belief before evolution?
the chain of being - ladder of increasing complexity
who is Carolus Linnaeus?
- father of taxonomy (biological classification)
- promoted hierarchal, nested classification
(note that linnaues was a taxonomist, not an evolutionist, he did not believe natural selection)
What are fossils?
-rocks of different age in the same location containing different species from differing
What did Lamarck propose about fossils and evolution?
- observed progressions of similar species in the fossil record
- proposed new species arise by modification of existing species (A turns into B turns into C)
What were Lamarck’s ideas about pattern of evolution?
He proposed the living world was made up of many separate lineages with independent origins and each lineage progressed for perfection/complexity (he was wrong)
What were lamarcks ideas about the process of evolution?
the Use and Disuse of parts idea with inheritance of aquired characters. an individual will evolve and then pass those changes onto their offspring
Were Lamarck’s ideas correct?
No!
What did Darwin propose?
Natural selection
What was Darwins idea on the pattern of evolution?
- Living things were united in one branching tree of relationships
- new lineages made by the splitting of existing lineages
What does the splitting of a lineage have to do with relation?
An earlier split results in greater difference while a later split results in a more common ancestor which allows for there to be more similarities between species
** note that after the splitting they share common ancestors (similar) but also are independent after the split
What was Darwin’s idea on the process of evolution?
-Darwin proposed natural selection
What are the aspects of natural selection?
1) Heritable variation
2) excess production
3) differential success
What is heritable variation?
- Individuals in a population are born with traits
- Many traits can be passed on from parents to offspring
What is excess production?
- In any population more offspring produced than needed to maintain it
- when resources are limited, offspring fail to survive
What is differential success?
- due to differing traits some individuals are more likely to survive (fitness)
- these traits increase in frequency while unfavourable traits are less frequent (evolution)
What is artificial selection?
Artificial selection on heritable variation present in existing species
- show plausibility of natural selection
What is adaptation?
Natural selection over time creates organisms well suited to their environment
What are some examples of natural selection in action
Drug resistance in pathogens, positive resistance, host switching insects, warfarin resistance, soapberry bug
What is required for a good visual of natural selection?
strong selective pressure and short generation times
- this is so we can see the changes in a generation obviously and quickly rather than waiting for light changes over generation, like the neck length of giraffes
Describe how warfarin resistance in rats demonstrates natural selection?
Rats that are exposed to warfarin have resistance increase rapidly in the population because they build resistance and the weak die. -
Does natural selection create variations?
No! Natural selection only works on pre existing variations (rat mutation)
Is natural selection beneficial in these rats?
Not necessarily. Natural selection does not always act to improve the rat, simply based on the environment. In the rat’s case, when they were no longer exposed to warfarin they were not able to create vitamin K as effectively, resulting in malnourishment