Chapter 22: Darwin and Descent with Modification Flashcards
What are the 3 key observations about life?
- Organisms are suited for their environments
- Many characteristics of life are shared
- Life is very diverse
What are Darwin’s 4 central ideas?
- Descent with Modification
- Common Ancestry
- Adaptation
- Natural Selection
What is Darwin’s first central idea and what exactly does it mean?
- Descent with Modification
- “change over time”
- This was his phrase for “Evolution”
What is Darwin’s second central idea and what exactly does it mean?
- Common Ancestry
- When species have similar characteristics due to a recent ancestor
What is Darwin’s third central idea and what exactly does it mean?
- Adaptation
- when organisms inherit characteristics that enhance their survival and reproduction for that specific environment
What is Darwin’s fourth central idea and what exactly does it mean?
- Natural Selection
- a process by which organisms with certain heritable traits survive and reproduce at a higher rate than those in the population who lack those traits
Natural selection produces ___________.
adaptations
What is catastrophism?
When a catastrophic event occurs and many species go extinct
- theory by George Cuvier
What did Lamarck propose?
He argued 4 laws
- Organisms become more complex
- The environment applies stresses
- As a result, organisms develop new parts
- New parts (changes) are passed on
Why is Lamarck’s proposal flawed?
- It doesn’t happen at the level of population
- If an individual giraffe gets its neck stretched it doesn’t mean that its offspring will suddenly have long necks also
What did Lyell argue?
- Earth is older than 6000 years
- Earth is also changing, meaning that it is encouraging the species to evolve as environmental changes occur
- If organisms continue to evolve but Earth cannot provide the right environment to support them then they go extinct
What is artificial selection?
Humans modify other species by selecting and breeding individuals that possess desired traits
What is Carlos Linnaeus responsible for?
The binomial format for naming organisms
Genus and Species
What is Thomas Malthus responsible for?
He theorized that human disease and famine resulted from the human population’s ability to increase faster than the available food supply
What is Alfred Wallace responsible for?
He developed the theory of natural selection entirely independently from Darwin and sent it to Darwin for approval
What does the fossil record reveal and how/why is it evidence for evolution?
- It reveals species from the past and shows a change
- It is evidence for evolution because it is physical proof that a species has evolved (changed) over time
- However, the fossil record is incomplete because it favors structures that are easier to preserve
- DNA also cannot be obtained from fossils
What are homologous structures?
Structures of organisms that represent a common theme from a common ancestor
E.g., bones of bat wing and bones of gorilla arm are similar
What is biogeography and how do biogeographical patterns support evolution?
- A geographic distribution of species
- For example, when land drifts apart (e.g. Australia) those species become isolated and remain there (koalas, kangaroos etc.)
- These patterns support evolution because we can track where current species originated from and it shows how they evolved
What type of evidence for evolution has come from molecular biology?
DNA!
Evolutionary relationships can be determined based on genes and proteins from different organisms
What are some examples of direct observations of evolutionary change?
- Soapberry bugs and the Golden Rain Tree
- Antibiotic Resistance
What is convergent evolution?
- The independent evolution of similar features in different lineages
(These organisms do not have common ancestors, but their similar features developed independently)
Why is convergent evolution a problem for building trees?
- Just because two species have similar structures it doesn’t mean they share common ancestors
The ___________ (longer/shorter) it has been since two organisms shared a common ancestor, the __________ (smaller/greater) the number of base differences we should see between similar genes.
Longer, greater
True or False
Natural selection is the only cause for evolution
False
True or False
Natural selection is the only mechanism that produces adaptations
True
