10.4 - Evidence for Evolution

Question 1

How did the evolutionary theory develop?

Up to Darwin*

Answer 1

1809- Most believed the Bible’s literal sotries

1831- Prinicples of Geology (Lyell) - suggested fossils were evidence of past animals

Lyell & Uniformitarianism - principle that Earth is shaped by forces seen today (sedimentation, wind erosion, as & lava deposition) - challenged Biblical ideas.

Darwin concluded evolution was a slow process.

Question 2

What occured with Darwin on the Galapagos Islands?

Answer 2

• Paid observation to finches, noticed they were similar, must be related but with different beaks & claw shapes/sizes
  
  • concluded finches beaks were linked to the available food
    
    • Conclusion: bird born with beak more suited to env. would survive, bird w/out wouldn’t ⇒ more offspirng bass on characteristic beak
• Darwin sent samples to UK for testing to find characteristic links ⇒ experimental work on pigeon breeding

Question 3

What happened when Darwin worked with Wallace?

Answer 3

Wallace peer reviewed work, realising they had similar ideas ⇒ worked together (1858)

• 1859 - Origin of Species (Darwin)
  
  • Theory of evolution by natural selection
    
    • contrversioal aas it conflicted with religious views of God. e.g. Humans from ape or God?

Question 4

Give 3 pieces of evidence for evolution.

Answer 4

Paleontology - study of fossil & fossil record

Comparative anatomy - study of similariteis & differences between organism’s anatomy

Comparative biochemistry - sim/diff between organism’s chemical composition

Question 5

What is a fossil?

Answer 5

• Formed of animal & plant remains preserved in rocks
  
  • over prolonged period of time, sediment is deposited in strata (layers) corresponding to geological eras (most recent at top) - fossil record

Question 6

(Paleontology) Give evidence for fossil record.

Answer 6

1. Fossils of simplest organisms (e.g. bacteria & algae) are oldest in rock, more complex organisms in newer rock - supporting evolutionary thoery that life from has evolved over long time periods.
2. Sequences in which organisms bmatches ecological link. E.g. plant fossile appear before animal - animals need plants to survive
3. Anatomical similarities show relation of organisms
   
   1. How they evolve from same ancestor

Question 7

Why is fossil record incomplete?

Answer 7

Soft-bodied organisms decompose quickly before fossilising

Most fossils are destroyed by volcanoes and Earth’s movement

Question 8

How is comparing anatomy, evidence for evolution?

Answer 8

Homologous structure - structure which is superficially different, but internally the same

Question 9

How is comparing biochemistry, evidence for evolution?

(Molecular Evidence)

Answer 9

• DNA, proteins and RNA exist in all living organisms
• Variation is caused by DNA change ⇒ protein change
• Over the time taken for evolution, DNA changes accumulate, so the closer the DNA and protein structure, the more related an organism is

Question 10

How do scientists discover how closely organisms (2 species) are related?

Answer 10

• By comparison of molecular sequence (order of DNA bases or aas order in proteins)
  
  • No. of difference plotted against rate of molecular neutral base pair substitution
  • Scientists can estimate when 2 species shared a common ancestor
• rRNA and fossils used to determine relations between ancient species as rRNA has slow substituion rate.