Lecture 3: History of Evolutionary Thought Flashcards

Darwin and Evolutionary Thinking before the Modern Synthesis

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1
Q

one of the most influential texts of this century.

A

Origin of Species by Charles Darwin

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2
Q

What was Charles Darwin’s initial career pursuit?

A

Medicine

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3
Q

Where did Charles Darwin study botany?

A

Christ’s College, Cambridge

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4
Q

Who encouraged Darwin to join the Voyage of the Beagle?

A

Rev. John Henslow

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5
Q

Which ship did Charles Darwin embark on for his scientific expedition?

A

HMS Beagle

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6
Q

Who and what was Charles Darwin’s father and grandfather’s profession?

A
  • Richard Darwin (father)
  • Erasmus Darwin (grandfather)
  • Doctors
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7
Q

What subject did Charles Darwin pursue a passionate interest in while at Christ’s College, Cambridge?

A

Natural History

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8
Q

Where did Charles Darwin make a major find of fossil bones during his voyage?

A

Punta Alta, Patagonia

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9
Q

What expertise did Darwin have during the voyage?

A

Geology
beetle collecting
marine
invertebrate dissection

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10
Q

Where are the Galapagos Islands located?

A

Pacific Ocean, west of continental Ecuador

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11
Q

What did Darwin conclude about the populations of species on the Galapagos Islands?

A

They descended from a common ancestor and were evolving.

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12
Q

What did Darwin question after observing the populations on the Galapagos Islands?

A

The stability of the concept of a “species.”

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13
Q

where did Darwin first observe mockingbirds that sparked his interest?

A

Galápagos, near Sappho Cove on Chatham Island (now Isla San Cristóbal)

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14
Q

What did Darwin notice about the mockingbirds on different islands in the Galápagos?

A

They differed slightly in size, shape, and coloration.

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15
Q

Who informed Darwin that tortoises also differed from island to island in the Galápagos?

A

Nicolas Lawson, acting Governor of Galápagos

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16
Q

What did Darwin speculate about the distribution of mockingbirds and tortoises towards the end of the voyage?

A

Their distribution might undermine the stability of species, suggesting that species are not fixed entities but change over time.

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17
Q

What did Darwin conclude about the mockingbirds after observing them on different islands?

A

They must have shared a common ancestor and were not independently created.

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18
Q

What did exposure to animal diversity during the voyage lead Darwin to conclude about species?

A

1) “Species” are not immutable fixed entities
2) Organisms are related by common ancestry (tree-like branching)
3) They are changing and branching in response to the environment (“Adaptation”)

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19
Q

Who did Darwin marry upon his return to England?

A

Emma Wedgewood

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20
Q

What historical developments provided the scientific context for the development of Darwin’s theory of evolution?

A

Discoveries in geology, including the understanding that the Earth is older than previously thought, and the fossil record showing changes in species over time.

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21
Q

What influential scientific theory did Lamarck propose before Darwin?

A

The inheritance of acquired characteristics.

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22
Q

Who influenced Darwin’s idea of competition and the struggle for survival?

A

Thomas Malthus, through his work “Essay on the Principle of Population.”

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23
Q

What idea did Darwin develop from Malthus’ work?

A

The concept of competition and the “struggle for survival” as components of natural selection.

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24
Q

Who independently came up with the idea of natural selection around the same time as Darwin?

A

Alfred Russel Wallace

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25
Q

What did Darwin and Wallace decide to do after learning about each other’s work?

A

joint presentation at the Linnean Society in 1858.

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26
Q

What was the title of Alfred Russel Wallace’s manuscript that he sent to Darwin?

A

“On the Tendency of Varieties to Depart Indefinitely from the Original Type”

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27
Q

When did Darwin publish “On the Origin of Species”?

A

1859

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28
Q

What are Darwin’s main points in “On the Origin of Species”?

A

1) Organisms evolve
2) Common descent: species arise from common ancestors
3) Gradualism: changes occur gradually
4) Population speciation: change in proportions of individuals with a trait in a population
5) Natural selection as the mechanism of adaptive evolution.

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29
Q

What was Lamarck’s view on the pattern of evolution?

A

Linear progression, often depicted as a “ladder of life” or “great chain of being.”

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30
Q

How did Darwin view the pattern of evolution?

A

As a tree-like branching process.

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31
Q

What was Lamarck’s proposed mechanism of evolution?

A

Inheritance of acquired traits at the individual level.

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32
Q

What was Darwin’s proposed mechanism of evolution?

A

Evolution at the population level via natural selection.

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33
Q

What is the problem with the “ladder of life” concept in Lamarck’s view of evolution?

A

It implies progress and a linear progression, which is not consistent with the branching nature of evolution.

34
Q

What were some limitations of Darwin’s theory of evolution?

A
  • Because Darwin knew nothing about mutation, he had no idea how variation was generated in populations
  • Because Darwin knew nothing about genetics or genes, he had no idea how variation was passed on to offspring (Mendel & Hardy-Weinberg)
  • Darwin did not know about nonadaptive evolutionary forces, such as Genetic Drift
35
Q

What did Mendel’s work provide a mechanism for in terms of inheritance?

A

How traits are passed on from parents to offspring, through the idea of particulate (gene) inheritance.

36
Q

When was Mendel’s work initially published, and when was it rediscovered?

A

Mendel’s work was published in 1865 but was ignored until it was rediscovered in 1900.

37
Q

Who were the scientists credited with rediscovering Mendel’s laws of inheritance?

A
  • Dutch biologist Hugo de Vries
  • German plant geneticist Carl Correns
  • Austrian plant breeder Erich von Tschermak-Seysenegg.
38
Q

What mathematical concept, related to Mendelian inheritance, did Hardy and Weinberg develop?

A

The Hardy-Weinberg equilibrium, which describes the mathematical expectations of Mendelian inheritance and whether those expectations are realized in nature.

39
Q

Mendel and Darwin’s ideas seemed Incompatible
* Mendel’s principles: dealt with __ (e.g. __, __)
* BUT, Darwin observed __ (e.g. __, __)

A
  • particulate (discrete) traits
    –> yellow vs. green
    –> wrinkled vs. smooth
  • continuous traits
    –> beak size
    –> body length
40
Q

Mutations discovered after __

A

1900

41
Q

They thought that evolution required only mutations and passing on of discrete traits

A

Mutationists (+ Mendelianism)

42
Q

They thought that evolution required only Natural Selection on continuous variation

A

Darwinists

43
Q

Darwin was unable to clearly see the pattern of inheritance because he studied __

A

quantitative variation

44
Q

Darwin did not understand the __ (what is being inherited, genes)

A

unit of inheritance

45
Q

a trait that has distinct values, rather than a range of phenotypes, usually encoded by one or a few genes.

A

distinct trait

46
Q

examples of distinct traits

A
  • number of fingers
  • color of Mendel’ s peas
  • sickle cell anemia
  • ABO blood type
  • number of eggs in a bird clutch
  • presence/absence of human widow’s peak
  • presence/absence of dimples, etc.
47
Q

a trait that has a continuum of phenotypes and is encoded by multiple genes.

A

Quantitative (continuous) trait

48
Q

examples of Quantitative (continuous) trait

A

body size
Height
Weight
intelligence (IQ)
Running speed
beak shape
hair color
skin color
milk yield of cows
lifespan, etc.

49
Q

Proponents of the Darwinist Theory

Proponents of Darwinism were correct about mechanisms of __, but they did not understand what __ was acting on, as they were unaware of the __ or how the variation was passed on to the next generation.

A
  • Natural Selection
  • Selection
  • unit of inheritance (genes)
50
Q

Proponents of the Darwinist Theory

They came up with the idea of __ where offspring gain characteristics of both parents, like mixing colors of paint… but, this was a vague idea that was __

A
  • “Blending inheritance”
  • incorrect
51
Q

Proponents of the Darwinist Theory

Many of them were __ (statistical types) that thought that evolution was gradually acting on continuous traits

A

Biometricians

52
Q

Proponents of the Mutationist/Mendelist Theory

Many Prominent __ at the time supported the Mutationist/Mendelist theory

A

Geneticists

53
Q

Proponents of the mutationist theory included __, among those who “discovered” Mendel’s 1900 paper.

A

Hugo de Vries

54
Q

Proponenets of the mutationist theory included __, founder of Drosophila genetics

A

Thomas Hunt Morgan

55
Q

Thought that evolution arose through genetic changes (mutations) that were discrete and sudden

A

Proponents of the Mutationist/Mendelist Theory

56
Q

Proponents of the Mutationist/Mendelist Theory

New species originated when they mutated from pre-existing species, but this process was independent of __

A

natural selection

57
Q

Controversy between Mutationists vs Darwinists

Controversy persisted for __ years up till the __, during which little progress was made

A
  • ~30
  • 1930s
58
Q

Problems to Resolve
* At the heart was the question of whether __ and __ could be reconciled with mechanisms of __.
* A second issue was whether the broad-scale changes (__) seen by palaeontologists could be explained by changes seen in local populations (__).

A
  • Mendelian genetics
  • Mutation
  • Natural Selection
  • macroevolution
  • microevolution
59
Q

the mendelian and darwinism problem is caused by

A
  • Binary thinking (Black or White thinking)
  • Inability to see overarching mechanism
60
Q

what could explain a wide range of phenomena, like “How could your Hardy-Weinberg (Mendel) explain the inheritance of 5.1 cm, 5.5 cm beak length (continuous characters)?”

A

overarching mechanism

61
Q

A concept as important as Natural Selection
But, not as prominent on people’s minds

A

Genetic drift

62
Q

When was The Modern Synthesis

A

1930s-1940s

63
Q

The Modern Synthesis is also called

A

“Synthesis of Evolution and Genetics”

64
Q

The Modern Synthesis

The synthesis of population genetics
integrate the roles of :

A
  • mutation
  • Selection
  • genetic drift
  • Paleontology
  • Systematics
65
Q

Darwin and Mendel Reconciled

A

The Modern Synthesis

66
Q

Among the Greatest Scientific Revolutions of the Century

A

The Modern Synthesis

67
Q

Three of the “architects” of the evolutionary synthesis:

A
  • G. Ledyard Stebbins Jr.
  • George Gaylord Simpson
  • Theodosius Dobzhansky
68
Q

__ was important because many scientists from different fields convened to discuss the evolutionary mechanisms and clear up confusion and inconsistencies

A

The Evolutionary Synthesis

69
Q

Some Key Tenets of the Modern Synthesis:

Natural Selection and Mutation are not the only evolutionary forces. Give other examples:

A

Examples: Genetic Drift, Migration

70
Q

Some Key Tenets of the Modern Synthesis:
are the units of Evolution

A

Populations

71
Q

Some Key Tenets of the Modern Synthesis:
are sources of genetic variation upon which Selection acts

A

Mutations

72
Q

Some Key Tenets of the Modern Synthesis:
Microevolutionary processes, such as __, __, __, lead to Macroevolutionary changes

A
  • Drift
  • Selection
  • Mutation
73
Q

Some Key Tenets of the Modern Synthesis:

Acquired characters (__) are not inherited

A

phenotypic plasticity

74
Q

Some Key Tenets of the Modern Synthesis:

Traits are inherited via __, and they do not “__” with other genes (Darwin was wrong about this one)

A
  • genes
  • blend
75
Q

Genes mutate, resulting in __

A

different alleles

76
Q

Evolution occurs at the __, due to a change in proportions of individuals with different genotypes

A

population level

77
Q

Changes in proportion in a population could occur via __ (Sewall Wright) or __… the rate of mutation is usually too low to cause large changes in proportions

A
  • random genetic drift
  • Natural selection
78
Q

Even very weak natural selection could cause __ over a longer time scale

A

substantial changes

79
Q

generate the genetic variation upon which natural selection acts

A

Mutations

80
Q

Microevolutionary processes lead to Macroevolutionary changes

A

speciation

81
Q

All organisms on the planet are related to one another in a great “tree of life”, and have diverged by branching from __

A

common ancestors

82
Q

Gaps in the fossil record are likely due to incompleteness of the __ . Gradual changes seen in many parts of the fossil record suggest gradual changes over time

A
  • fossil record