Lecture 3: History of Evolutionary Thought

Question 1

one of the most influential texts of this century.

Answer 1

Origin of Species by Charles Darwin

Question 2

What was Charles Darwin’s initial career pursuit?

Answer 2

Medicine

Question 3

Where did Charles Darwin study botany?

Answer 3

Christ’s College, Cambridge

Question 4

Who encouraged Darwin to join the Voyage of the Beagle?

Answer 4

Rev. John Henslow

Question 5

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

Answer 5

HMS Beagle

Question 6

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

Answer 6

• Richard Darwin (father)
• Erasmus Darwin (grandfather)
• Doctors

Question 7

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

Answer 7

Natural History

Question 8

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

Answer 8

Punta Alta, Patagonia

Question 9

What expertise did Darwin have during the voyage?

Answer 9

Geology
beetle collecting
marine
invertebrate dissection

Question 10

Where are the Galapagos Islands located?

Answer 10

Pacific Ocean, west of continental Ecuador

Question 11

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

Answer 11

They descended from a common ancestor and were evolving.

Question 12

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

Answer 12

The stability of the concept of a “species.”

Question 13

where did Darwin first observe mockingbirds that sparked his interest?

Answer 13

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

Question 14

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

Answer 14

They differed slightly in size, shape, and coloration.

Question 15

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

Answer 15

Nicolas Lawson, acting Governor of Galápagos

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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”)

Question 19

Who did Darwin marry upon his return to England?

Answer 19

Emma Wedgewood

Question 20

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

Answer 20

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

Question 21

What influential scientific theory did Lamarck propose before Darwin?

Answer 21

The inheritance of acquired characteristics.

Question 22

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

Answer 22

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

Question 23

What idea did Darwin develop from Malthus’ work?

Answer 23

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

Question 24

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

Answer 24

Alfred Russel Wallace

Question 25

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

Answer 25

joint presentation at the Linnean Society in 1858.

Question 26

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

Answer 26

"On the Tendency of Varieties to Depart Indefinitely from the Original Type"

Question 27

When did Darwin publish "On the Origin of Species"?

Answer 27

1859

Question 28

What are Darwin's main points in "On the Origin of Species"?

Answer 28

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.

Question 29

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

Answer 29

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

Question 30

How did Darwin view the pattern of evolution?

Answer 30

As a tree-like branching process.

Question 31

What was Lamarck's proposed mechanism of evolution?

Answer 31

Inheritance of acquired traits at the individual level.

Question 32

What was Darwin's proposed mechanism of evolution?

Answer 32

Evolution at the population level via natural selection.

Question 33

What is the problem with the "ladder of life" concept in Lamarck's view of evolution?

Answer 33

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

Question 34

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

Answer 34

- 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

Question 35

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

Answer 35

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

Question 36

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

Answer 36

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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

- particulate (discrete) traits --> yellow vs. green --> wrinkled vs. smooth - continuous traits --> beak size --> body length

Question 40

Mutations discovered after __

Answer 40

1900

Question 41

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

Answer 41

Mutationists (+ Mendelianism)

Question 42

They thought that evolution required only Natural Selection on continuous variation

Answer 42

Darwinists

Question 43

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

Answer 43

quantitative variation

Question 44

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

Answer 44

unit of inheritance

Question 45

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

Answer 45

distinct trait

Question 46

examples of distinct traits

Answer 46

- 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.

Question 47

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

Answer 47

Quantitative (continuous) trait

Question 48

examples of Quantitative (continuous) trait

Answer 48

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

Question 49

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.

Answer 49

- Natural Selection - Selection - unit of inheritance (genes)

Question 50

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 __

Answer 50

- “Blending inheritance” - incorrect

Question 51

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

Answer 51

Biometricians

Question 52

Proponents of the Mutationist/Mendelist Theory Many Prominent __ at the time supported the Mutationist/Mendelist theory

Answer 52

Geneticists

Question 53

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

Answer 53

Hugo de Vries

Question 54

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

Answer 54

Thomas Hunt Morgan

Question 55

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

Answer 55

Proponents of the Mutationist/Mendelist Theory

Question 56

Proponents of the Mutationist/Mendelist Theory New species originated when they mutated from pre-existing species, but this process was independent of __

Answer 56

natural selection

Question 57

Controversy between Mutationists vs Darwinists Controversy persisted for __ years up till the __, during which little progress was made

Answer 57

- ~30 - 1930s

Question 58

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 (__).

Answer 58

- Mendelian genetics - Mutation - Natural Selection - macroevolution - microevolution

Question 59

the mendelian and darwinism problem is caused by

Answer 59

* Binary thinking (Black or White thinking) * Inability to see overarching mechanism

Question 60

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)?”

Answer 60

overarching mechanism

Question 61

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

Answer 61

Genetic drift

Question 62

When was The Modern Synthesis

Answer 62

1930s-1940s

Question 63

The Modern Synthesis is also called

Answer 63

“Synthesis of Evolution and Genetics”

Question 64

The Modern Synthesis The synthesis of population genetics integrate the roles of :

Answer 64

* mutation * Selection * genetic drift * Paleontology * Systematics

Question 65

Darwin and Mendel Reconciled

Answer 65

The Modern Synthesis

Question 66

Among the Greatest Scientific Revolutions of the Century

Answer 66

The Modern Synthesis

Question 67

Three of the "architects" of the evolutionary synthesis:

Answer 67

- G. Ledyard Stebbins Jr. - George Gaylord Simpson - Theodosius Dobzhansky

Question 68

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

Answer 68

The Evolutionary Synthesis

Question 69

Some Key Tenets of the Modern Synthesis: Natural Selection and Mutation are not the only evolutionary forces. Give other examples:

Answer 69

Examples: Genetic Drift, Migration

Question 70

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

Answer 70

Populations

Question 71

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

Answer 71

Mutations

Question 72

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

Answer 72

- Drift - Selection - Mutation

Question 73

Some Key Tenets of the Modern Synthesis: Acquired characters (__) are not inherited

Answer 73

phenotypic plasticity

Question 74

Some Key Tenets of the Modern Synthesis: Traits are inherited via __, and they do not “__” with other genes (Darwin was wrong about this one)

Answer 74

- genes - blend

Question 75

Genes mutate, resulting in __

Answer 75

different alleles

Question 76

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

Answer 76

population level

Question 77

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

Answer 77

- random genetic drift - Natural selection

Question 78

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

Answer 78

substantial changes

Question 79

generate the genetic variation upon which natural selection acts

Answer 79

Mutations

Question 80

Microevolutionary processes lead to Macroevolutionary changes

Answer 80

speciation

Question 81

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

Answer 81

common ancestors

Question 82

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

Answer 82

- fossil record