Exam 3

Question 1

What are some advantages when fighting?

Answer 1

1. Fighting in own territory, knows environment better than most.
2. Knowing the value of winning the fight.

Question 2

What stages do animals go through when fighting?

Answer 2

1. Assessment: judging what will happen if a fight were to breakout. Who would win? Is there an unfair advantag? What are the costs/benefits?
2. Escalation: animals begin to fight

Question 3

What is honest signaling? Provide an example.

Answer 3

Phenotypic expressions/structures that an organism displays, influencing observers behaviors based on that display.

Harris sparrow birds have head coloration known as a “badge”. The birds with the darker badges tend to win the most fights. A cost of having a darker head is that they will only be challenged by other good fighters. In an experiment, some birds without a badge were dyed to give off that display and were challenged by the skilled fighting birds (fake signals).

Question 4

What is the difference between males and females in terms of sexual selection?

Answer 4

Males: have small gamete and sperm
Females: have large gamete and egg

Question 5

Why are males under much more pressure to mate than females?

Answer 5

It is harder for males to mate because sperm is much cheaper than the egg. The egg is the most valuable thing.

Question 6

In terms of reproduction, what are males and females limited by?

Answer 6

Females are limited by access to resources and males are limited by access to eggs. (Bateman’s principle)

Question 7

What is the difference between anisogamy and isogamous?

Answer 7

Anisogamy: not the same gamete (almost all of nature)
Isogamous: having the same gamete across species (very rare)

Question 8

What sex ratio is considered an ESS?

Answer 8

50:50 male:female is an ESS.

Question 9

What is intrasexual selection? Provide an example.

Answer 9

Within a sex selection (male-male or female-female competition).

Male bluegill sunfish will swim next to each other and push water at each other to determine who is the bigger and stronger fish.

Female Kribensis cichlids will swim at each other and gliding past each other to show off the number of eggs in their stomach. The bulge in their stomachs with bright colors represents how many eggs it has.

Question 10

What is intersexual selection? Provide an example.

Answer 10

Selection between the sexes.

Mate choice: choice by the females of the male. Some female organisms prefer males with bigger access to territories and food supply so that their offspring can be easier to raise. Widow birds are sexually selected for the length of its tail. In an experiment, Malte Anderson attached a males tail to another to make one extra long. The males with extra long tails had massive mating numbers while the shorter ones did not do much mating at all.

Question 11

What is the idea of the Lek Paradox?

Answer 11

The hypothesis that the sexual selection of females for particular traits leads to very little genetic variation in males.

Question 12

Give an example of how asymmetry is selected in males.

Answer 12

Female Stalk eyed flies prefer those with the most symmetrical body. Uneven symmetry in the body shows that a disease had swept through the organism at some point.

Question 13

What does the Fisherian principle/runaway selection state for sexual selection?

Answer 13

Fisherian states that females choose the males with the most attractive physical traits so that her sons will have a better chance of mating as well. These physical traits offer no type of benefits besides the appearance.

Question 14

What is the handicap principle?

Answer 14

The idea that females like males because their genes are able to have this handicap trait that they carry with them for so long, and will pass these strong genes to offspring. The exaggerated traits tell the female that they are able to carry this handicap and it makes them stronger.

Question 15

What is monogamy? Provide example

Answer 15

One male is mates with just one female. Albatross birds practice monogamy.

Question 16

What is polygamy?

Answer 16

Not monogamy.

Question 17

What is polygyny? Provide example.

Answer 17

One male mates with multiple females. Elephant seals practice polygyny because the male mates with multiple females while each female mates with just one male.

Question 18

What is polyandry? Provide example

Answer 18

One female mates with multiple males. In Phalarope birds, the male makes the nest and the female stops nest to nest and mates with each male.

Question 19

What is polygynandry?

Answer 19

A female mates with multiple males and a male mates with multiple females, with choice.

Question 20

What is promiscuity? Provide example

Answer 20

No choice; males mate with multiple females and vise versa. Pacific herring fish mate rapidly and drip all gametes with no choice, leaving before they get eaten.

Question 21

According to the Emlen + Oring hypothesis, what three things must be known to predict the female dispersion of a population? What predicts the male dispersion?

Answer 21

1. Resource dispersion
2. Predation
3. Costs + benefits of social living

Male dispersion always depends on female dispersion.

Question 22

What is the benefit of male territoriality?

Answer 22

If a male has a territory to himself, he will control a large chunk of the resources, drawing females to his territory. In some species, males try to control the three Emlen + Orinc hypothesis factors by having this territory.

Question 23

Why is there a curve of diminishing returns on parental investment?

Answer 23

As a parent invests more into their offspring, less is invested into the future. This creates the curve or diminishing returns.

Question 24

What is an example of biparental investment?

Answer 24

In cichlids, the parents care for the offspring together even thought they do not remain mates for life. Cichlid offspring require biparental investment because the offspring will be eaten if they are unattended. They must cooperate, but find a balance of investment from each parent so both can save some for future offspring. The ESS is at the point of the graph where the male does the maximum investment that the female does.

Question 25

What are some tagible benefits for sexual selection?

Answer 25

1. Fighting: in most species, usually the best fighter is sexually selected upon because they can be trusted to protect offspring.
2. Territory and food supply: female organisms prefer males with bigger access to territories and food supply so the offspring will be easier to raise

Question 26

What is an example of runaway sexual selection (Fisherian)?

Answer 26

In peacocks, males have beautiful tails because females want it, females want it because her sons will have a better chance of mating.

Question 27

What is an example of the handicap principle?

Answer 27

Females like peacocks with large tails because he is strong enough to carry around the tail, showing good genes. Females prefer the exaggerated traits because it is a handicap and, yet, the male thrives.

Question 28

How does disease play a role in the handicap principle?

Answer 28

At a certain point, a species in a population can’t get anymore “better” than it already is and, therefore, they are all selected upon the same. Disease becomes the only character that can constantly change and males are selected upon based on how well they overcome certain diseases.

Question 29

According to runaway sexual selection (Fisherian), how do these exaggerated traits by males affect their viability and mating success?

Answer 29

Males and their offspring with exaggerated traits will not have increased viability (actual performance) but will have enhanced mating success.

Question 30

How did the Ims (Norway) experiment prove the Emlen + Oring hypothesis to be true?

Answer 30

Grey-sided voles were studied and taken all off of the island. The females were placed back on the island in cages. The males were then released into the island. Males set up territories based off where the females were in cages. The experiment was recreated but the males were first in cages. The females were not concerned about where the males were at all, and rather where the best resources were.

Question 31

What are some of the costs/benefits of group living?

Answer 31

Costs: larger groups are more attractive to predators, but smaller cost than benefit of having safety in numbers. Diseases spread much easier. Competition.

Benefits: safety in numbers, probability of death goes down. Intimidation.

Question 32

What happened in William Hamilton’s selfish herd?

Answer 32

In a circle of frogs and a snake predator, frogs will continuously move out of the snakes line of sight, increasing the death probability of the frog next to him.

Question 33

Give an example of a species that use group living as an intimidation factor

Answer 33

Musk-oxen surround their young so wolves/predators cannot attack it:

Question 34

What is the many-eyes hypothesis?

Answer 34

Ostriches we’re studied to see how many in the group looked around vs ate. As group size went up, vigilance went up.

Question 35

In group foraging, what is the benefit of being vigilant?

Answer 35

Being the first individual to spot a predator is a benefit.

Question 36

How do some organisms use confusion effect when group foraging?

Answer 36

Some organisms falsely alarm of predators for a bigger portion of food.

Question 37

What are some costs and benefits of the confusion effect of having similar morphology’s?

Answer 37

Having similar morphologies will make you stand out less in the presence of predators, but will make mating have less value because everyone looks the same.

Question 38

What are producers and scroungers?

Answer 38

Producers are good at finding food, scroungers follow the producers and contribute nothing.

Question 39

What is an ESS?

Answer 39

An ESS is a strategy which, when adopted by most members of the population, cannot be invaded by any other mutant strategy.

Question 40

What are the costs and benefits of being a hawk/dove in the hawk-dove game?

Answer 40

Hawks: always fight.
Benefits- get what they want
Costs- injury or death from fighting

Doves: will display but not fight
Benefits- less likely to get injured
Costs- often do not get reward

Question 41

In a hawk-dove payoff matrix, what happens with each encounter?
Prize: 50 points
Cost of injury: -100 points
Cost of display: -10 points

Answer 41

When hawk attacks other hawk, it will win prize half the time and be injured other half (-25 points)

When hawk attacks dove, it will win prize every time (50 points)

When dove attacks other dove, it will win prize half time by displaying and miss out other half (15 points)

When dove approaches hawk, it will flee (0 points)

Question 42

What is the ESS ratio of hawks:doves and how is it derived?

Answer 42

When h-bar = d-bar
-25h + 50(1-h) = 0h + 15(1-h)
-25h + 50 - 50h = 0h +15 -15h
35h = 60
h = 7/12

7 hawks, 5 doves is ESS

Question 43

When a third strategy is introduced to a hawk-dove game, what is it and how does it behave?

Answer 43

Bourgeois: fights hard if it is the owner, retreats if it is the intruder.

Question 44

how does the prisoners dilemma work?

Answer 44

If two cooperate with each other, R = 3 (mutual cooperation)

If one defects another that is cooperating, T = 5 (temptation)

If one cooperates with another that is defecting, S = 0 (suckers payoff)

If two try to defect each orher, P = 1 (punishment for mutual defection)

Question 45

Describe “tit-for-tat” in prisoners dilemma

Answer 45

Tit-for-tat refers to when a prisoners dilemma participant chooses a strategy consistent with what his opponent has a history of.

Question 46

Can we predict who will win in fights?

Answer 46

Generally no, the opponent thinks he has a chance otherwise there would be no fight.

Question 47

What are some physical attributes that will contribute to success in a fight?

Answer 47

1. Physical ability
2. Injury history
3. Size

Question 48

How does territoriality play a role in fighting?

Answer 48

Territoriality is beneficial for whoever’s territory it is. They will have home-field advantage. Owners know what the value of their territory is and have won it in the past.

Question 49

How do we know if a trait is a product of sexual selection?

Answer 49

There is a positive correlation between mating success and that trait.

Preference y-axis, trait x-axis