Evidence for Evolution

Question 1

What is natural selection?

Answer 1

• organisms best suited to their environment are more likely to survive, reproduce, and pass on their advantageous characteristics to their offspring.

Question 2

Who proposed natural selection theory?

Answer 2

Wallace and Darwin independently

Question 3

Darwin summary

Answer 3

• Galapagus islands
• unusual species similar to mainland species
• variation between members of the same species
• offspring look like parents
• no two individuals are identical
• large number of offspring
• pop stable
• competition keep pop in check
• less adapted animals are more likely to die
• over time many variation that are beneficial arise in population
• new species
• new finches beaks diet niche

Question 4

Explain how we can use fossils to provide evidence for evolution…

Answer 4

• paleontology (study of life history recorded in fossils)
• organisms preserved in rock layers
  -fossils found in sediments further underground are older than those above
• show how organisms gradually change over time as simple algae and bacteria in old rocks vs complex vertebrates in newer
  -plant fossils appear before animal (natural order)
• anatomical sim between fossils demonstrate shared ev ancestry
• extinct compared to living species to understand ev relationships

Question 5

Why is the fossil record incomplete?

Answer 5

• Many organisms decompose before they can fossilise, only hard parts
• Fossilisation is uncommon, requires specific conditions for an organism to be preserved.
  -Over time, many fossils have been lost due to erosion or geological processes.
  -Many organisms have not yet been discovered.
  -Certain organisms, especially those with soft bodies, are less likely to fossilise, leading to gaps in the record.

Question 6

Explain how we can use comparative anatomy to provide evidence for evolution…

Answer 6

• examine anatomical structure of different living species for sim and diff
• sim structure = common ancestor
• Homologous structures = physical features in different species that have a similar underlying structure but may serve different functions.
• Organisms who share homologous structures likely evolved from a common ancestor, and have adapted these structures for different functions.
• Homologous structures are evidence for divergent evolution, where organisms evolve different adaptive traits as they occupy new ecological niches.
• pentadactyl limb common shared in vertebrates bone structure

Question 7

Explain how we can use comparative biochem to provide evidence for evolution…

Answer 7

• studying molecular aspects of organisms to uncover ev relationships
• cytochrome c - highly conserved protein in resp so slight changes = identify ev link
• rrna - protein synthesis so changes slowly
• DNA sequences more sim if closely related
• mRNA - base sequences of mRNA are complementary to DNA so assess DNA diversity
• AA seq as det by mRNA + DNA