Exam 2

Question 1

What is the formula for profitability? Give an example

Answer 1

Energy/Handling time

Naked peanuts: no handling time, instant energy
Peanuts in shell: some handling time
Walnuts: most handling time

Question 2

What is the optimal diet theory?

Answer 2

The theory that animals should forage based off whatever will maximize their energy intake and minimize their foraging time

Question 3

What are the 3 predictions of the optimal diet theory?

Answer 3

1. The predator should either specialize only in the most profitable prey (E/H) or it should include both items in its diet; be a generalist.
2. The decision to be a specialist or a generalist depends on the abundance/search time of the most profitable item.
3. The switch from specializing on the most profitable to generalizing (eating both) should be sudden (depending on the abundance of the most profitable item) (NOT THE CASE)

Question 4

Describe risk as a currency

Answer 4

Risk is a currency that does not accumulate.

Question 5

What are two risk strategies?

Answer 5

Risk averse strategy: organism will prioritize safety over taking a risk on something greater

Risk prone strategy: organism will have to face risk prone scenarios because risk averse strategy does not provide enough energy content

Question 6

What happens when an organism constantly faces risk? Provide an example

Answer 6

Organisms will slowly adapt over time to the risks that they constantly face.

Bluegill sunfish in two different ponds began to look different. Both ponds had bass predators hunting them. One pond had an excess of vegetation while the other was wide open. The vegetation pond bluegills grew bigger pectoral fins for sharper turns through the vegetation. The open pond bluegills had smaller pectoral fins to swim faster.

Question 7

What is the difference between incomplete metamorphosis vs complete metamorphosis?

Answer 7

Incomplete metamorphosis does not include a pupa stage, instead a nymph stage where they resemble the adult. Complete metamorphosis is when an organism undergoes a complete change physically.

Question 8

What is the M/g concept? Provide an example

Answer 8

M= size/age-specific mortality
g= size/age-specific growth

Want M/g to be as low as possible

As tadpoles, life starts hard, gets increasingly easier, then gets hard again. Tadpoles can choose to metamorphosize to frogs earlier on to prolong their life. Adding predators to a tadpoles environment will make them metamorphosize sooner.

Question 9

Describe the M/g graph.

Answer 9

The y-axis is M/g, the x-axis is size/age. Curve of graph is U-shaped for tadpoles. Dotted curve to the right of it is life of frogs.

Question 10

What are evolutionary arms races? How do they start? How do they end?

Answer 10

Evolutionary arms races occur when two co-evolving populations undergo changes in phenotype and behavior over time to counter the other. There is usually multiple counter evolution stages between each species.

Evolutionary arms races start when the benefit of evolving outweighs the cost of energy.

Evolutionary arms races rarely ever end. If anything, a population will drive another population down until there is no longer an abundance and seek a different prey. That other population will then increase again and the arms race will continue.

Question 11

What is an original example of an evolutionary arms race?

Answer 11

The co-evolution between water snails and crabs. Crabs hunt snails for prey by crushing their shells with their pincers and then eating the snail. To resist, snails evolved to grow thicker shells that are not as easy to crush. To counter this change, crabs developed sharper edges on their pincers that make it easy to crush their thicker shells. The snails then evolved to reside in shells that resemble rocks that are inedible. This made it harder for crabs to spot prey and figure out where a snail is when near rocks.

Question 12

What is crypsis? Give an example

Answer 12

An organisms ability to avoid detection from another organism.

It does not have to be perfect and prey is not trying to be invisible, just wants to avoid detection.

For example, stone plants appear to be stones so predators will choose to eat something more profitable.

Underwing moths have a startle display where their wings look like large eyes, scaring off predators.

Question 13

What can be some costs of crypsis? Give an example.

Answer 13

During crypsis, time spent hidden can cost time spent foraging and mating. Some organisms that use crypsis must stay in one spot for an extended period of time.

Question 14

What is a search image? Give an example

Answer 14

The idea that vertebrates can scan an area for something specific that they desire

When predators have a search image, prey will try to not look like this typical image to be “efficiently invisible”

Coral snakes are an extremely venomous snake species, other organisms will try to mimic their pattern/colors so that predators will stay away.

Question 15

Do some organisms go out of their way to be seen? Provide an example

Answer 15

Some organisms, such as flowers, go out of their way to be seen for pollination.

Question 16

Can some organisms be visible when they want to be and hidden when they want to?

Answer 16

Yes, the morpho butterfly has bright blue wings on the outside to enhance chance of mating while having has brown, leaf colored back side wings to avoid predator detection.

Question 17

What happened when John Endler studied the spots on guppies in different rivers?

Answer 17

Endler studied the differences of spots on guppies in different rivers. Guppies with no predators around kept their bright spots while guppies with predators around lost their bright spots.

Question 18

Why is the idea of prudent predation not the case of ending an evolutionary arms race?

Answer 18

This is the idea that predators save prey for different times since their is an abundance, which would suggest group selection.

Question 19

What is the idea of the asymmetric game?

Answer 19

The cost of not winning an encounter is much higher for the prey than it is for the predator. The prey’s entire life is saved while the predator just misses out on an opportunity to gain energy.

Question 20

What is a brood parasite? Provide an example

Answer 20

A brood parasite is an organism that relies on its others to raise their young. The host is manipulated into thinking the offspring is one of its own.

Cuckoo birds is an example by using egg mimicry to trick wrens into believing they are it’s own.

Question 21

How have cuckoo’s perfected brood parasitism?

Answer 21

Cuckoo’s have patterns in their mouth recognized by other birds to get fed. Cuckoos also kill other birds in the nest so that their energy portion is higher.

Question 22

What is the cost of discrimination? Provide an example.

Answer 22

Cost of discrimination involves an action that might cost you but could also end up very beneficial. For example, if a cuckoo egg appears bigger, a wren parent does not kill it because it could be their best offspring.