UNIT 2 DAY 3 - DARWIN BUILDS A THEORY

Question 1

Darwin returns to England

Answer 1

• Darwin’s first earned professional recognition from collection of species he brought home
• he had different experts examine his collection of species

Question 2

Endemic species

Answer 2

species that are native to and found only within a limited area

Question 3

Darwin’s Speculations on Transmutation

Answer 3

• notebook from beagle (red notebook) –> used these to document his thoughts

Question 4

Darwin’s New Grand Fact of Natural History

Answer 4

• species are replaced not because of God but because previous species transform into later species
• Endemic species of the Galapagos arise from a series of transmutations as they move from one island to the next, changing under differing conditions of each island and preventing from merging back together

Question 5

Darwin’s first big idea

Answer 5

• common descent
• all living things can be organised into a single tree of common descent
• according to Darwin, the reason one can group organisms is because they share ancestors
• explains why the pattern of species are replaced by similar species

Question 6

Evolution according to Darwin

Answer 6

• like a branching tree, showing how species split and diverge into separate lineages as they change
• all species ultimately share a common ancestor

Question 7

Evolution according to Lamarck

Answer 7

• series of parallel escalators
  -erroneous view –> primitive species arise repeatedly by spontaneous generations and then evolve without branching into more advanced species

Question 8

Jenny, Young Orangutan

Answer 8

• Darwin observed her at London Zoo
• First of her species ever seen there
• compared Jenny to Fuegians –> not much of a difference between them
• environment causes fuegians to act like animals
• realises that humans aren’t that different from animals

Question 9

Darwin’s second big idea

Answer 9

• natural selection
• species are simply varieties
• small differences are the building blocks of evolution

Question 10

Natural Selection

Answer 10

• individuals who have variants better suited for environment are more likely to survive and reproduction –> reproduction will pass along adaptation

Question 11

Darwin and Animal/plant breeding

Answer 11

• individuals that happen to process traits best fitting to current environment and survive long enough to reproduce
• breeding individuals that possess traits sought after by breeders are reproduced

Question 12

Varieties

Answer 12

simply populations that have generated enough differences to look different from one another

Question 13

New Species

Answer 13

species are varieties that have generated enough variation to be separated

Question 14

Darwin’s deductive arguments

Answer 14

1. Struggle for existence
2. Selection argument
3. evolution argument

Question 15

Struggle for Existence

Answer 15

• if all organisms reproduce above replacement rate, but populations generally do not grow in size, and if resources remain limited, then a struggle for existence must result
• in each generation most who are born will die before reproducing
• predicts that in each generation only a lucky few will survive

Question 16

Selection Argument

Answer 16

• if in each generation, only a few organisms survive, and if organisms vary, and if survival is not random, but instead is influenced by traits that vary, then a trait that makes survival more likely will be more common among the survivors than it was before mortality ensued
• predicts that the lucky few will differ from the unlucky multitude in being more likely to possess some traits that helped them survive

Question 17

Evolution argument

Answer 17

• if such an advantageous trait is more common among the survivors, and if the trait is heritable, then it will also be more common among the offspring of the survivors, who then too will have a better chance at surviving (each generation, the trait will increase in frequency in the species and the species will change overtime in ways that keeps it closely fitted to its environment)
• predicts that future generations will therefore differ from those of the past in ways that better fit them to the current environment, because that advantageous trait will be more widespread in the species than it was before

Question 18

Objections to Natural Selection

Answer 18

• one species can’t change into another because the intermediates would have no place in nature
• range of complexity of organs (human eye)

Question 19

How Grand Fact #3 changed

Answer 19

• before Darwin –> members of each species are equipped with exactly the features they need in order to survive, revealing god’s power and beneficence
• after darwin –> the close fit of each species to its place in nature remains a central concept of biology, but with natural selection as its explanation rather than the direct hand of god
• Sedgwick not happy with Darwin leaving God out
• He believed that any scientific theory that failed to incorporated the designer was defective

Question 20

How Grand Fact #2 Changed

Answer 20

• Before Darwin: Species can be ordered into natural groups, revealing God’s rational plan of creation
• After Darwin: we still classify species into natural groups now reflect shared descent rather than a divine plan –> humans are related by descent to all other humans

Question 21

How Grand Fact #1 Changed

Answer 21

• Before Darwin: Species are real and unchangeable, each created individually by god
• After Darwin: Species are mutable, are best understood by population thinking rather than essentialist thinking

Question 22

Essentialist View

Answer 22

• species have no history / never change
• unchanged until it goes extinct
• clearly distinguishable

Question 23

Darwinian View

Answer 23

• species have a history
• evolved overtime into the species it is today
• gradual change

Question 24

Population thinking

Answer 24

• Ernst Mayr
• Evolution by natural selection, requires a different way of thinking about species one that can comprehend entities that are not clearly distinguishable and that morph slowly from one into another
• focuses on individual variation within species

Question 25

Little rhea confirm what?

Answer 25

• proved that species everywhere come from a similar previous species

Question 26

When did Darwin begin to question God’s involvement in species?

Answer 26

• when he saw that a large amount of different species has slightly different varieties

Question 27

Competition for resources –> positive adaptation for population

Answer 27

• individuals compete for resources, those better suited to their environment live to survive and reproduce –> pass down beneficial genes –> others that are weaker will die off and not reproduce

Question 28

How does reproducing above ‘the replacement rate’ lead to evolution?

Answer 28

• high population and limited resources leads to competition –> leads to survival of the fittest
  1. struggle for existence argument –> only some survive
  2. selection argument –> some survive due to advantageous traits
  3. evolution arguments –> future generations inherit these advantageous traits which leads to evolution of the population

Question 29

Objections to tranmutations

Answer 29

• species can’t go from one to another because ‘intermediated’ have no place in nature
• tight coordination on parts of organisms means changing one will disrupt the organisms functionality –> things move from simple to complex through gradual changes of small improvements

Question 30

Adaptation meanings

Answer 30

1. refer to a particular feature of an organism
2. state of being adapted
3. process which natural features evolve by natural selection