Lecture 2

Question 1

What is an animal model system?

Answer 1

Using animals to investigate biological systems

Question 2

Why do we use animal model systems?

Answer 2

As an attempt to find generalizations between animals and humans. Also, animals have shorter lifespans, so development can be viewed

Question 3

When studying animals, are we interested in finding a role model for human behaviours?

Answer 3

No. Many animals show behaviours that wouldn’t be appropriate for humans, but are natural in the animal world.

Question 4

What is the naturalistic fallacy?

Answer 4

Something we want to avoid. Idea that what happens in nature is good or inevitable. Just because something happens in nature doesn’t make it good or bad.

Question 5

Why does infanticide occur in black and white colobus monkeys?

Answer 5

Because the males are trying to solve problems in their reproductive environment-by killing the alpha males infants, it removes his genetics from the pool. Females will mate with the males who have taken over

Question 6

What does it mean that nature is witless?

Answer 6

Nature is impartial. It is not kind or cruel, not good or bad, not something to strive for, it’s neutral

Question 7

What is the main process of evolutionary change?

Answer 7

Natural selection

Question 8

What does natural selection require?

Answer 8

Variation for different responses. There is no one best way

Question 9

What is Darwins theory of natural selection (3 parts)

Answer 9

1) Individuals face environmental challenges that could be detrimental to the survival
2) Some individuals are better able to respond to those challenges in their current environment than others (Based on how wisely they use energy and respond)
3) All things being equal, genes and attributes of better responders will go on to be better represented in the next generation.

Question 10

What is differential reproduction?

Answer 10

The idea that some individuals leave behind more offspring than others

Question 11

What is reproductive success?

Answer 11

The number of offspring an individual currently has = currency of success from an evolutionary perspective.

Question 12

What is the proximate level of causation?

Answer 12

Asks questions that look for an immediate cue/trigger (ex: why do birds migrate? Immediate response is that they hate the cold- can look at hormonal levels to determine this)

Question 13

What is the ultimate level of causation?

Answer 13

Always concerns reproductive success (ex: Why do birds migrate? Compare reproductive success in birds who migrate versus those who don’t)

Question 14

What is genetic/biological determinism (AKA sociobiology controversy)

Answer 14

The belief that some behaviours are solely caused by biological/genetic factors. Nature overrides nurture. These traits are therefor difficult/impossible to change.

Question 15

What is the influence of genes on behaviour?

Answer 15

Genes influence behaviour, but don’t dictate behaviour. Biology is not destiny, but it does affect probability.

Question 16

What does evolutionary theory predict in terms of males and females?

Answer 16

It predicts relatively few differences between males and females. Both males and females equally need to survive, and we expect similar survival traits in successful individuals. Both sexes have similar survival traits

Question 17

Where are sex differences normally found?

Answer 17

In the domains of mating and reproduction

Question 18

What are the 2 levels of difference?

Answer 18

1) Differences in body form

2) Differences in behaviour

Question 19

What are differences in body form?

Answer 19

Sexual reproduction requires a male body and a female body. This allows for genetic material to be combined and not copied.

Question 20

What are the 2 different contexts of behaviour?

Answer 20

1) Within a mating context

2) Outside of mating context- are there sex differences outside of reproductive contexts?

Question 21

What are secondary sex characteristics and some examples?

Answer 21

Traits that vary between the sexes, but are not necessary for the physical aspect of reproduction. Examples: Colourful peacock, male moose with antlers. Traits that aren’t related to the primary reproductive system

Question 22

What are the 2 features about secondary sex characteristics that Darwin noticed?

Answer 22

1) Costly to produce- uses up energy that can’t be used elsewhere by males
2) Traits make males more obvious to predators.
Both of these facts don’t make sense with natural selection, because they are detrimental to survival.

Question 23

What is the theory of sexual selection?

Answer 23

Body of theory to explain how sex differences between males and females evolved. Similar to, but different from natural section. Traits provide an advantage in mating and acquiring a mate. How well you respond to your social environment. *We expect sex differences in sexual selection.

Question 24

What are the 2 methods of sexual selection?

Answer 24

1) Intrasexual competition

2) Intersexual competition

Question 25

What is intrasexual competition?

Answer 25

Competition between the sexes. Usually male-male competition. Direct competition between members of the same sex for a mate. Results in size evolution.

Question 26

What is intersexual competition?

Answer 26

Usually female choice. Some traits have evolved because one sex prefers them in members of the other sex. Results in ornaments on males or displays by males.

Question 27

What is evolution and what are the mechanisms of change in evolution?

Answer 27

A change in gene frequencies of a population over time. Mechanisms of change are natural and sexual selection

Question 28

Why do males compete?

Answer 28

To exclude rivals and mate more often.

Question 29

What is a limiting resource on male reproductive success?

Answer 29

Females

Question 30

How do male elephant seals demonstrate intrasexual competition?

Answer 30

They come ashore before the females and fight each other for social dominance. The top-ranking male does most of the mating (80% of male elephant seals do not mate). Adult females arrive on the beach after fighting, and the male monopolizes the female. Size is determinant of success, female gets no choice.

Question 31

What is size dimorphism?

Answer 31

When one sex is small and one is big. Demonstrates that the larger sex competes for access to mates. This gives them an advantage

Question 32

What is characteristic of female choice?

Answer 32

Females pay more attention to elaborate traits and can notice small differences in these traits. Much more problematic in research. There is a relationship between the trait and the tendency to mate. Unsure of mechanisms, but this doesn't really matter.

Question 33

How do the Sage Grouse use female choice?

Answer 33

During the breeding season, the males congregate in lek (Breeding grounds). Physical and vocal displays happen. Females observe and pick the most attractive males based on acoustic and visual displays. Most females get to mate, only a few males get to.

Question 34

How do the Bowerbirds use female choice?

Answer 34

Collects thousands of blue items and other items to attract females into their bower (mating/courtship arena). They then expand pupils alternatively, call, puffs self up, waves wing, twitches. Picks up blue item and presents it, then head butts the female.

Question 35

What are females looking for at the proximal level?

Answer 35

What they prefer in a mate. Displays are motivated by female preference

Question 36

What are females looking for at the ultimate level?

Answer 36

Good genes hypothesis

Question 37

What is the good genes hypothesis?

Answer 37

Idea that exaggerated displays may indicate good health and genetics. They are honest signals of health and quality. Good genes could lead to better offspring health. Bad health means they wouldn't have the energy for external displays. Female choice is not just about looks, also about health.