Chapter 50-Behavioural Ecology

Question 1

Behavioural Ecology

Answer 1

study of the behavioural adaptations that evolved in response to ecological selection pressures

Question 2

Proximate (or mechanistic) causation

Answer 2

explains how actions occur

Question 3

Ultimate (or evolutionary) causation

Answer 3

explains why actions occur

-based on natural selection. Behaviour is a part of phenotype

Question 4

EX: Do male redback spiders benefit from being eaten by their mates?

Answer 4

• The male actively solicits his own consumption, and females never eat males that do not somersault onto their jaws
• This allows him to insert two sperm packets into female sperm receptacles

Question 5

How is the process with these spiders done?

Answer 5

Before a male mates, an abdominal constriction forms and protects his heart and other vital organs.
- As a result, he survives the attack long enough to insert his second sperm package, ↑ the number of spiderlings
(can transfer twice as many sperm)
- more successful at plugging the receptacles of their mates, preventing other males from inserting additional sperm

Question 6

EX: Argentine ant behaviour

Answer 6

In their native range, the ants live in colonies and defend territories by fighting with neighbours
In S California, ants show no aggression, move among adjacent nest, and thus form “supercolonies”

Question 7

Proximate Cause of argentine ants

Answer 7

ants identify each other via scent - hydrocarbon tags
- This scent is genetically determined, but the ants have almost no genetic variation in this allele, so an ant can’t tell if another is from its colony or not, but see native ants, with unfamiliar scents, as enemies

Question 8

Ultimate causes of argentine ants

Answer 8

Supercolonies make Argentinian ants superior competitors and therefore the lack of diversity is adaptive in S. California
- low genetic diversity has its dangers: If the supercolony faces a pathogen, the entire colony may collapse

Question 9

Fixed-action patterns (FAPs)

Answer 9

highly inflexible, stereotypical behaviour patterns

Question 10

Learning

Answer 10

enduring change in behaviour that results from a specific experience (flexible)

Question 11

Innate behaviour

Answer 11

requires no learning (fixed)

Question 12

Fitness trade-offs

Answer 12

compromises balancing costs and benefits

Question 13

Cost–benefit analysis

Answer 13

behavioural decisions are measured in terms of their impact on fitness

Question 14

2 things about cost-benefit analysis:

Answer 14

1. The choices made by non-human animals are not conscious choices
2. Individuals’ behaviour varies within populations

Question 15

foraging

Answer 15

when animals seek food

-always making choices

Question 16

EX: Fruit flies

Proximate Causes: Foraging alleles

Answer 16

Fruit fly larvae exhibit one of two behaviours during feeding:
“Rovers” move after feeding in a particular location
“Sitters” stay in one location to feed•
Experiments showed this behaviour inheritable via the foraging (for) gene that produces a protein active in the nervous system
Adult flies express the same foraging alleles as larval flies

Question 17

EX: Fruit flies

Ultimate Causes: Optimal foraging

Answer 17

The rover allele is favoured at high population density
Rovers are more likely to find unused food patches•

The sitter allele is favoured at low population density Sitters do not waste energy searching for food

Question 18

Optimal foraging

Answer 18

–individuals make decisions that maximize the amount of food (usable energy they take in)
–weigh costs of finding and ingesting their food and the risk of being eaten while they’re at it

Question 19

EX: Arctic Seals

Answer 19

have to find shallow water with plenty of food to avoid over-exhausting themselves

Question 20

EX: Bumblebees

Answer 20

want to fly short distances between flowers to save the most energy and obtain the most honey

Question 21

EX: Do desert gerbils exhibit optimal foraging?

Answer 21

Control group-without extra seeds
Treatment gorup-with extra seeds
Both exhibit an owl flying over

Results: w/o extra seeds, did not take risk
w extra seeds, took the risk
therefore gerbils weigh the risk of predation and benefits of extra seeds when foraging

Question 22

Proximate vs Ultimate in Sexual activity

Answer 22

proximate mechanisms responsible for triggering sexual activity
Why animals choose their mates?-ultimate

Question 23

EX:How is sexual activity triggered in Anolislizards (proximate)?

Answer 23

Anolis have a breeding season, i.e., their sexual condition changes seasonally
Individuals ready to breed in spring, although male gonads start growing long before female. In both sexes, the gonads shrink afterwards

Question 24

Testosterone and estradiol

Answer 24

The evidence for the effects of sex hormones is direct
–Injected testosterone induces courtship activity in castrated males with no prior courtship activity; estradiol injections induce sexual activity in females whose ovaries have been removed

Question 25

Testing the light and social stimuli for lizards

Females vs males

Answer 25

Females: Need to experience spring-like light and temperatures or they do not produce eggs
Males signal females to induce estradiol release:
–During courtship, they bob up and down and extend a brightly coloured patch of skin called a dewlap. The dewlap is the estradiol trigger in females
–Females are slow to produce eggs when exposed to males without dewlaps or males that do not court (castrated)

Question 26

Ultimate causes: Sexual selection

Answer 26

Synchronizing sexual readiness → more offspring (=higher fitness than those that do not)
Energy and resource savings (long tails and bright colours
Visible features are an honest signal of male quality

Question 27

Intrasexual selection

Answer 27

when males (or females) compete with each other for mates

Question 28

Proximate causes: How do animals navigate? (3)

Answer 28

1. Piloting: use familiar landmarks
2. Compass orientation: movement oriented in a specific direction
3. True navigation: ability to locate a specific place on Earth’s surface

Question 29

Piloting

Answer 29

offspring seem to memorize the route by following their parents south in the fall and north in the spring
(not easy to tell whether an individual uses landmarks (piloting) or a combination of that and mapping)

Question 30

Compass orientation

Answer 30

Multiple mechanisms for finding a compass direction
- Sun compass
- star compass
- magnetic compass
The Sun is difficult to use as its position changes throughout the day

Question 31

Circadian clock

Answer 31

maintains a 24-hour rhythm of chemical activity

Question 32

Use of magnetic field -How?

Answer 32

• Animals’ visual systems may be able to detect it through a chemical reaction that involves electron transfer among molecules
• they may have small particles of magnetic iron (magnetite) in their bodies, allowing them to detect changes in Earth’s magnetic field

Question 33

EX: Sea turtles navigate using map (True) orientation

Answer 33

Experiment: place soft harnesses over wild turtles and monitor swimming direction in diff artificial magnetic fields
Results: Simulated North location-swam south
Simulated South Location-swan North
Both trying to return to actual location of turtles

Question 34

Communication

Answer 34

social process in which a signal from one individual can modify the behaviour of another individual

Question 35

signal

Answer 35

information-containing behaviour

Question 36

Proximate causes: How do honeybees communicate?

Answer 36

Karl von Frisch observed bees displaying a “round dance” to workers, as well as a “waggle dance
He placed feeders at several distances from the hive and marked the bees that came to the feeders
Observations:
1.Danced when they returned to the hive
2.Returned to the food source with unmarked bees

Question 37

waggle dance contains information about food location (3)

Answer 37

1. The length of the waggle run was proportional to the distance from the feeder
2. The direction of the waggle run correlated with the direction to the food source
3. The direction of the food source is relative to the current position of the Sun

Question 38

Ultimate causes: Why do honeybees communicate the way they do

Answer 38

The signal is appropriate to its habitat and type of info needed (helps the whole colony)
Animals use a diversity of signals: sound, scent, or tactile or visual cues, often in combination
Each mode of communication has advantages and disadvantages (think of fitness).

Question 39

Deceiving Individuals of Another Species

Answer 39

individuals sometimes increase their fitness by providing inaccurate or misleading information to members of a different species

Question 40

EX: Interspecifc -Fireflies

Answer 40

female fireflies attract males of diff species with flashes to attack male and eat him

Question 41

EX: Intraspecific -Bluegills

Answer 41

males bluegillds mimic females-look and act like females during courtship with terriotrial males (territorial male thinks he is courting 2 females)

• When the actual female begins to lay eggs, the mimic releases sperm and fertilizes some of the eggs
• In this way the female-mimic male fathers offspring but does not help care for them

Question 42

Why aren’t all males mimics?

Answer 42

Deceit works only when it is relatively rare
–If deceit becomes common, individuals that can detect and avoid or punish liars would be selected for
– more mimics, more competition → lower reproductive success of the mimic

Question 43

Altruism

Answer 43

behaviour that has a fitness cost to the actor and a fitness benefit to the recipient

Question 44

Self-sacrificing

EX: black-tailed prairie dogs

Answer 44

-perform alarm calling when predator is near (brings attention to them, but warns the rest)

Question 45

Hamilton’s rule states that altruistic behaviour is most likely when three conditions are met:

Answer 45

1. The fitness benefits of altruistic behaviour are high for the recipient (B is high)
2. The altruist and recipient are close relatives (r is high) 3.The fitness costs to the altruist are low (C is low)

Question 46

inclusive fitness

Answer 46

combination of direct and indirect fitness components

Question 47

Kin selection

Answer 47

natural selection that acts through benefits to relatives and results in increased indirect fitness
–decreases direct fitness but increases indirect fitness, resulting in an overall increase in inclusive fitness

Question 48

Eusociality

Answer 48

altruistic behaviour can be involuntary

ex: bee/wasp/ant workers sacrifice most/all direct reproduction to help queen’s offspring

Question 49

Reciprocal Altruism

Answer 49

exchange of fitness benefits that are separated in time

Question 50

Examples of Reciprocal Altruism

Answer 50

ex: vervet monkeys likely to groom unrelated individuals whom groomed/helped them in past
ex: vampire bats likely to share blood meals w non-kin who shared food w them in past

Question 51

Mutualism

Answer 51

occur when cooperation occurs among individuals of same species