Evolution and Comparative Method

Question 1

How many species are currently on the planet?

Answer 1

8.7 million

Question 2

How many species in all of Earth’s history?

Answer 2

1-5 billion

Question 3

What is evolution?

Answer 3

Change in the frequencies of alleles in a population over time

Question 4

What are alleles?

Answer 4

Gene variants

Question 5

What three things drive evolution?

Answer 5

Mutation, natural selection, and drift

Question 6

What three things do you need for evolution by natural selection?

Answer 6

Variation, selection, heritability

Question 7

Define variation

Answer 7

the population contains individuals with different traits

Question 8

Define selection

Answer 8

Individuals with cerain traits have higher chance of reproduction/survival

Question 9

Define heritability

Answer 9

Traits are genetic

Question 10

What does evolution by natural selection produce?

Answer 10

Adaptations

Question 11

What are adaptations

Answer 11

A fit between the organism and its environment

Question 12

What is genetic drift

Answer 12

A variation in the frequency of different genotypes in a small population, resulting from the chance disappearance of particular genes as individuals die or do not reproduce

Question 13

Describe what mutations are like in reality

Answer 13

• Will immediately disappear from the population if the individual is not viable
• Some will have very small effects on survival and reproduction. The smallest advantage is important, though and will lead to change.

Question 14

What is an adaptive trait

Answer 14

One that enhances an individual’s chance of success at survival and/or reproduction

Question 15

What is the reference point for chance of survival/reproduction

Answer 15

It is relative to others in the population

Question 16

What are adaptive explanations?

Answer 16

Explaining why an adaption is beneficial for an organisms survival/reproduction

Question 17

What are the four ways of testing adaptive explanations?

Answer 17

1. Compare existing variation in the population
2. Treat the behavior as a “design feature”
3. Create artificial variation in the population
4. The comparative method

Question 18

Explain the method of comparing variation in the population

Answer 18

Seeing whether or not organisms without a certain adaptation are susceptible to things that hinder their survival and reproduction. If so, what are these things?

Question 19

What is the disadvantage to the method of comparing variation in the population

Answer 19

Difficult to do if natural selection has already eliminated the alternatives

Question 20

Explain the treat the behavior as a design feature method

Answer 20

Imagining you wanted to design an animal that was optimal for surviving and reproducing in its environment given the diseases, predators, etc

Question 21

Explain the method of creating artificial variation in the population

Answer 21

Simulating animals that dont have a certain adaptation to test if they would survive and reproduce at a smaller rate

Question 22

What was the adaptive explanation for gulls throwing away their egg shells after their chicks were hatched

Answer 22

They used artificial variation in the population. They created artificial nests with eggs in them. Some were positioned near broken eggshells, others had no broken shells nearby.

Predators were much more likely to take eggs from nests with shells nearby than from nests with no shells nearby

Question 23

What type of adaptation is eggshell removal likely to be?

Answer 23

Antipredatory adaptation

Question 24

What is antipredatory adaptation

Answer 24

Reduces conspicuousness of nest

Question 25

What is the comparative method

Answer 25

Testing your hypothesis by comparing the behavior of different species. Finding species that are closely related to the animal, but whose environment differs from the animals' in one key way. If they dont perform or have the adaptation, this strengthens the case for your adaptive explanation explanation.

Question 26

What text introduced the comparitive method?

Answer 26

Harvey and Pagel 1991

Question 27

What does the comparitive method seek to understand

Answer 27

The drivers of evolutionary change and the adaptive value of specific traits

Question 28

How does the comparitive method go about understanding the drivers of evolutionary change and the adaptive value of specific traits

Answer 28

By relating the degree to which a species displays the trait with the degree to which the hypothesized selection pressure is present

Question 29

What are two important things to keep in mind with the comparative method?

Answer 29

The more species you compare, the better The more you know about how those species are related, the better

Question 30

What is phylogenetics

Answer 30

The study of the evolutionary history of species, and their relationships

Question 31

What is phylogeny?

Answer 31

A tree that depicts phylogenetic relationships

Question 32

How are phylogenetic trees reconstructed

Answer 32

By studying heritable traits and looking for shared characteristics

Question 33

What determines how close different species are on a tree

Answer 33

The number of traits the species share, and how similar these traits are

Question 34

What is the but when it comes to shared traits

Answer 34

They must be homologous, not analogous

Question 35

Define homologous trait

Answer 35

Shared traits because they were inherited from a common ancestor

Question 36

Define analogous trait

Answer 36

Traits that have the same function but different origins. Ex: evolved independently/convergently

Question 37

What three things can we use to understand the cognitive capabilities of extinct species?

Answer 37

Phylogenetics Anatomical measurements Archaeological evidence

Question 38

What can phylogenetics allow for

Answer 38

Inference of ancestral mental states

Question 39

Give an example of how anatomical measurements can lead to understanding cognitive capabilities of ancestral species?

Answer 39

Cranial capacity -> brain size -> inferred cognitive "sophistication"

Question 40

What can archaeological evidence provide

Answer 40

Traits implying the emergence of specific cognitive capacities

Question 41

Insert information from slide 22 and 23

Question 42

Give two examples of archaeological evidence in humans

Answer 42

Appearance of art - may signal appearance of abstract thinking/language Appearance of complex stone and tools - may signal appearance of enhanced planning, teaching, communication, cooperation, division of labor, etc

Question 43

Explain monkeys and tools (type monkey, type tool, timeline)

Answer 43

Capuchin monkeys in Brazil have been using stone tools for at least 3000 years Chimpanzees in West Africa have been using stone tools for at least 4300 years

Question 44

What does understanding behavior and cognition require

Answer 44

Understanding evolutionary past and present

Question 45

How can behavioral and cognitive adaptations be studied

Answer 45

Systematically ("Why does the animal do this?")

Question 46

What can comparing species provide

Answer 46

Insights into selection pressures that promote the evolution of specific traits

Question 47

What are Tinbergen's 4 questions

Answer 47

Mechanism, ontogeny, adaptation, phylogeny

Question 48

What two explanations from Tinbergen's 4 questions were mostly talked about in this slide deck?

Answer 48

The ultimate ones: adaptation and phylogeny

Question 49

What two explanations from Tinbergen's 4 questions were not really talked about in this slide deck?

Answer 49

The proximate ones: mechanism and ontogeny