Chapter 5

Question 1

How do gulls mob?

Answer 1

• exhibit mobbing behavior of potential predators
• adults will dive predators, make loud noises, and even splatter them with excrement
• may act as a distraction from offspring

Question 2

What is an adaptive value?

Answer 2

contribution to fitness of a character/ adaptation

Question 3

What is an adaptation, and what is required?

Answer 3

hereditary trait that spread by natural selection, replacing alternatives

must have better fitness-benefit-to-fitness-cost than alternative forms

Question 4

What is the predator-prey arms race?

Answer 4

any improvement avoiding capture would work as a selective force on predators

Question 5

Why is not every trait perfectly adaptive (4)?

Answer 5

• some traits may persists even when no longer adaptive
• some persist due to genes with both benefits and costs
• some traits are slow to develop
• mutations, pleiotropy (one gene produces multiple effects), and coevolution constrain adaptive value

Question 6

Why can failure of mutation occur? (2)

Answer 6

• selection can’t keep up with environmental change
  
  • can be man-made changes
• non or mal-adaptive traits can persist in recently invaded habitat

Question 7

How do arctic moths and arctic ground squirrels exhibit nonadaptive trait in a new environment?

Answer 7

arctic moths live in area with no bats but still respond to ultrasonic stimuli

arctic ground squirrels respond to snake stimuli

Question 8

How does pleiotropy prevent perfect adaptations?

Answer 8

if positive consequence outweighs negative ones, less perfect traits can persist

Question 9

What is an example of pleiotropy?

Answer 9

Misdirected parental care, where animals male adopt unrelated offspring

Question 10

What is coevolution, and an example?

Answer 10

individuals interact in ways that affect each other’s fitness, and evolution of traits in response to one another

host-symbiont; predator-prey

Question 11

How can coevolution prevent perfect adaptation (3)?

Answer 11

• evolutionary stability may never be reached, as a trait can be adaptive for one, but maladaptive for another
• as members of one group of species change due to selection pressure, a counter-response in another may occur
• if selective processes cannot generate an immediate effective solution to a change, less perfect change may remain for a time

Question 12

How is mobbing tested as an adaptation for gulls?

Answer 12

mobbing gulls should force distracted predators to use more searching effort than otherwise

egg-hunting carrion crows being mobbed were distracted and likely to find their prey

mobbing was not costly, as crows did not hurt gulls

Question 13

What is the predator distraction hypothesis in gulls?

Answer 13

benefit for gulls was proportional to the predators being mobbed

Question 14

How was the predator distraction hypothesis tested in gulls?

Answer 14

placed chicken eggs in various areas in the colony

those further away were more likely to be found due to differing mobbing pressures

Question 15

What is reproductive success?

Answer 15

how much offspring or grandoffspring reach reproductive success

Question 16

How is reproductive success measured?

Answer 16

survival, young fledged, number of mates inseminated, amount of food ingested, ability to obtain breeding territory

Question 17

How is fitness measured?

Answer 17

with some indicator of reproductive or genetic sucess

Question 18

What is the comparative method?

Answer 18

used to test predictions about which other species should or should not evolve a particular trait

Question 19

How is the comparative method used in mobbing?

Answer 19

if mobbing in gulls is evolved in response to predation, then other gull species with low risk of predation should not exhibit mobbing behavior

Question 20

What were gulls compared to?

Answer 20

early gulls were likely ground-nesting

a few species nested on ledges

Question 21

How did cliff nesters mob?

Answer 21

• cliff nesters have fewer nest predators, making mobbing less beneficial
  
  • these may have lost mobbing behavior
  • seen in black-legged kittywave

Question 22

What is a hypothesis of the original gull?

Answer 22

• original gull may have been cliff-nesting, but lost it and regained in some species
  
  • not parsimonious

Question 23

What did similar birds exhibit?

Answer 23

• similar selection pressure may lead to convergent evolution
  
  • unrelated species acting similarly
  • bank swallows mob snakes and blue jays
  • ground squirrels mob rattlesnakes

Question 24

What is the dilution effect?

Answer 24

fitness benefits to mass mating groups

Question 25

How do harvester ants exhibit the dilution effect?

Answer 25

- come together to mate a few days each year - forms dense aggregation - birds and dragonflies feed on swarms, but odds of being eaten is small

Question 26

How do butterflies exhibit dilution effect?

Answer 26

- puddling behaviors - increased conspicuousness of groups may be offset by chance of one being killed

Question 27

How do mayflies exhibit dilution effect?

Answer 27

- high densities of flies emerge as adults - greater the number of emerged females, the higher chance mayfly lives long enough to lay eggs

Question 28

What are advantages of the dillution effect (3)?

Answer 28

- improved or shared vigilance - communal defense - living shields

Question 29

What is the selfish herd concept?

Answer 29

- if an antelope were evenly dispersed when grazing - if a mutant arose and stood near individuals to shield itself - higher chance of attention, but lower chance of predation - if this mutation should spread, everyone should aggregate

Question 30

What is the game theory for social defense? (3)

Answer 30

- individuals are participants - success depends on competitors - competition is high for safest position

Question 31

How do blue gills and redshanks exhibit game theory?

Answer 31

- larger, dominant blue gills are found in the center - redshanks attacked by sparrowhawks were further from companions

Question 32

What does the game theory represent?

Answer 32

P= solitary payoff B= fitness loss as in solitary animals using others as a shield C= time spending searching for a shield

Question 33

When is social behavior favored in the selfish herd theory?

Answer 33

if B is greater than C, then social type should become greater over time

Question 34

Why does social behavior provide an adaptation?

Answer 34

since all-solitary population is vulnerable to invasion of mutant social type, then once it appears and spread, social becomes an adaptation

Question 35

What is cryptic behavior?

Answer 35

camouflage matching background

Question 36

How do peppered moths exhibit cryptic behavior?

Answer 36

- black form was rare, but then replaced by white and salt-peppered patterns - forms that were more easily seen had a higher risk of predation

Question 37

What must solitary organisms do differently from social ones?

Answer 37

they have more to gain by living longer, since that raises chance of reproduction

Question 38

What is color pattern reinforced by?

Answer 38

behavior, like choosing an appropriate background

Question 39

How do peppered moths exhibit behavior for its cryptic behavior?

Answer 39

- it tends to settle in shaded patches, below branches - birds are more likely to overlook moths on shaded branches

Question 40

How do Catocala relicta moths exhibit cryptic behaviors?

Answer 40

- perches on birch and light-barked trees - prefers light background - needs to be oriented with the tree pattern - those that are not are selected against and eaten

Question 41

What two anti-detection adaptation do moths exhibit?

Answer 41

substrate choice perching orientation

Question 42

What are the two costs for cryptic behavior?

Answer 42

- time and energy spent finding right background - time spend immobile during the day

Question 43

What are two examples of camouflaged insects having behaviors that make them obvious?

Answer 43

- walnut sphynx caterpillars whistles - peacock butterfly flicks wings and hisses when threatened

Question 44

When do cryptic insects announce their presence (2)?

Answer 44

- under attack - about to be attacked

Question 45

What is the result of announcing presence in cryptic insects?

Answer 45

predators often back off and are startled

Question 46

How do monarch butterflies make them obvious, and why?

Answer 46

- bright orange and black wing pattern - feeds on milkweeds that makes them distasteful

Question 47

how can an eaten monarch gain fitness if being eaten can kill it?

Answer 47

- trait evolved via indirect selection - dead individual saved a few of their close relatives

Question 48

How do monarch butterflies evolve through direct selection?

Answer 48

birds release immediately after grasping without killing them

Question 49

How do tephritid flies make itself obvious?

Answer 49

- flies wave wings to attract predators - markings resemble jumping spider legs - when waves are waved, it looks like aggressive leg-waving displays of spider

Question 50

How did we test that tephritid flies are mimicking spiders?

Answer 50

- wings were replaced with clear wings - modified flies did not scare off predators and were eaten - surviving flies were reattached with their original wings which scared off predator

Question 51

How do thomson's gazelle makes itself obvious?

Answer 51

when chased by predator, they leap and flare white rump patch- stotting

Question 52

What are three hypotheses about stotting?

Answer 52

stotting may allow them to scan other enemies alarm signal communication between gazelle and cheetah- correct

Question 53

What disproved the scanning hypothesis for stotting?

Answer 53

predicts that it occurs in places with tall grasses and shrubs, but it occurs in short grasses

Question 54

What disproved the alarm hypothesis for stotting?

Answer 54

- solitary gazelles stots - gazelle stots towards predator, not other gazelles