Lecture 15 And 16 Behavioral Ecology 1 Flashcards
What is the ethology?
The study of animal behavior from an evolutionary perspective
To gain understanding of a behavior, what should be understood?
Behavior patterns, proximate mechanisms, acquisition of behavior, ultimate causes of behavior
What are proximate mechanisms?
The name given to the neuronal, hormonal and anatomical mechanisms that underlie behavior
What are most behaviors the result of?
Complex interactions between inherited anatomical and physiological mechanisms and the ability to modify behaviors as the result of experience.
What are the ultimate causes of behavior?
The selection pressures that shaped its evolution
What describes most animal behavior?
Unlearned
Highly stereotypic
What is stereotypic behavior?
Always the same
Give an example of sterotypic, species specific behavior
Web spinning behavior of spiders- species can be identified by pattern of web
When may an animal fail to perform a genetically controlled behavior?
When environmental conditions needed to stimulate it are absent
Why might all individuals behave in the same way not due to genetically controlled behavior?
Because they all imitated the same teacher
How do genes cause a behavior?
Genes do not encode behavior
Gene products such as enzymes affect behavior by setting in motion interactions that underlie proximate mechanisms
How can genetic and environmental influences on the development of behavior be distinguished?
Deprivation experiments
Genetic experiments
What are deprivation experiments?
Investigators rear young so its deprived of all experience relevant of the behavior under study
What can be assumed if a behavior is still displayed during deprivation experiments?
The behavior develops without opportunities to learn it
What are genetic experiments?
Investigators alter the genomes of organisms by interbreeding closely related species, by comparing individuals that differ by only one or a few genes, or by knocking out/inserting specific genes
What were the conditions used for the deprivation experiment?
Newborn tree squirrel was reared in isolation on a liquid diet, in a cage without soil/particulate matter
What was the newborn squirrel given and what happened next?
A nut
Squirrel ran around cage and then resorted to stereotypic digging movements, then placed the nut in an imaginary hole and refilled the hole
What did the squirrel experiment show?
Heredity underlies food-storing behavior of this tree squirrel species, but is only expressed when environmental conditions allowed
What is selective breeding used for?
Select for anatomical traits and behavior
What does selective breeding provide an insight into?
Effects of genetic constitution on behavior
How did Konrad Lorenz investigate courtship displays of duck species?
Interbreeding/hybridization
What duck species are closely related and can interbreed?
Mallards, teals, pintails, gadwalls
How does the courtship displays of ducks work?
Male duck performs a choreographed water ballet typical of his species
Female accepts his advance only if entire display is successful and completed, skill judges quality
What happened when Lorenz crossbred different species of duck?
Hybrid offspring expressed elements of each parents courtship display in new combinations, as well as elements from neither species repitoire
What did Lorenz’s hybridization experiments show?
Stereotypic motor patterns of courtship displays are inherited
What did the observation that females are not interested in males performing hybrid displays give evidence to?
Sexual selection helped shape genetically determined behaviors
How have gene mutations that effect behaviors been studied?
On fruit flies and rodents using gene knockout and gene silencing techniques
What gene was studied in gene knockout experiments on rodents?
fosB gene
What behavior does a female house mice perform with an active fosB gene?
Gather her pups together, keep them warm and nurse them
What is the result of a mutated, inactivated fosB gene?
Mouse appears normal, but differs in how she treats new born pups
How do female house mice with inactivated fosB gene treat her new born pups?
Inspects them and then ignores them
How was the hypothesis that the absence of the fosB gene changes the maternal behavior of female mice tested experimentally?
Knock-out fosB gene in female mice, mate when mature
Immediately upon birth, separate mouse pups from mothers, three in opposite corners of the cage,
count the number of pups each mother retrieves within 20 minutes.
How does fosB gene influence maternal behavior?
Protein encoded by fosB is involved in stimulating neural changes in the hypothalamus of the mothers brain in response to olfactory molecules she encounters upon first inspection
Genetic control of behavior is ________ under many conditions.
Adaptive
Why are behavior patterns in many species so strongly influenced by genes?
Without opportunities to learn (particularly with non-overlapping generations) individuals might fail to acquire appropriate behavior
When mistakes are costly or dangerous
Give an example of behavior that does not have to be learned because mistakes are costly.
Kangaroo rats- avoid rattlesnakes by hearing them begin to strike and they hump through the air and out of the way
What is a releaser?
An object, event or condition required to elicit a behavior (such as the nut)
Give an example of a releaser triggering a behavior in birds.
Male robins: the sight of red feathers on an adult males breast during breeding season.
Male sings, performs aggressive displays and attack
How was the hypothesis that a wasp learns the location of her nest by visual cues tested experimentally?
Surround nest entrance with moveable visual cues and move them to another location after the wasp leaves and has surveyed her surroundings
What happened when visues cues around the wasps nest were moved?
The wasp orientated to the displaced cones and count not find entrance
What is it called when learning takes place only at a specific time in an animals development?
Critical period
What is the type of learning called when an animal learns a set of stimuli during the limited critical period?
Imprinting
What is an example of behavior learned by imprinting?
Recognition of offspring by their parents and of parents by their offspring
Give an example of imprint learning where the parent learns to recognize their offspring.
Emperor penguins- the father must find his chick after being away for weeks by recognizing its call
What can determine the critical period for imprinting?
Brief developmental or hormonal state
How does imprinting work in goats?
A mother goat must nuzzle or lick newborn in first 10 minutes or she will not recognize her own offspring
What causes the brief imprinting time in goats/ determines critical period?
High levels of the hormone oxytocin in the mother’s circulatory cyctem at the time she gives birth and olfactory cues from newborn kid
Give an example of an animal species that uses species-specific song in territorial displays and courship in which learning is an essential step.
White-crowned sparrow
How do hormones determine when a behavior is performed or learned?
Controlling influences on development and on the physiological state of the animal
What happened when investigators injected female songbirds with testosterone in the spring?
The females developed their species-specific song
What does an increase in testosterone in the spring do a songbirds brain?
Makes parts of the brain responsible for learning and developing song to grow larger
How do parts of a songbirds brain grow larger?
Individual neurons grow larger in size and longer extensions
Number of neurons increases
Why is selecting a place to live an important decision for an animal to make?
It influences survival and reproductive success
What cues do organisms use to select suitable habitats?
Predictors of conditions suitable for future survival and reproduction
What marine mollusk sticks to rocks and doesn’t move very far as an adult?
Red abalone
Where is the best place for a red abalone to live?
Coralline algae, its major food source
How do red abalone algae recognize coralline algae?
By a chemical the algae produces
Chemosensory cue
What other cues can be used to provide quality information?
Visual
Give an example of a species that use visual cues to asses quality of a potential habitat?
Collared flycatchers peer into nests of others to see how well neighbors are doing
What are conspecifics?
Other individuals of the same species
When might an animal establish a territory?
When high-quality habitats are in limited supply and competition is high
What approach is applied to understand territory behavior?
Cost-benefit approach- animal has limited time and energy
What are the three components of the total cost of a particular behavior?
- Energetic cost
- Risk cost
- Opportunity cost
On what type of lizard was cost-benefit territory behavior studied?
Male Yarrow’s spiny lizards
When do male Yarrow’s spiny lizards defend their territory from male conspecfics?
September and october
When did the lizard experiment take place?
June and july
How was the hypothesis that testosterone-induced agressiveness is too costly for Yarrow’s spiny lizards to maintain year round tested?
Insert testosterone capsules under skin of males during summer and observe behavior and survivalship
What were the results of the lizard experiment?
Testosterone-treated males were more active and displayed more territorial behaviors than untreated males
Treated males survived less well than untreated males
Name some other animals that display territorial behavior.
Tigers (defending multipurpose territory) Grouse species (defending mating territory) Seabirds (defending nesting site)
What name is given by applying the cost-benefit behavior to animals choosing what to eat?
Foraging theory
What does foraging theory help us to understand?
The survival and value of feeding choices
How is food characterized?
By the time it takes to capture, persue and consume the item
The amount of energy the item contains
What is the most valuable food type?
The one which yields the most energy per unit time expended
What do animals do if the abundance of the most valuable food type per unit time foraging is high enough?
The animal takes only the most valuable food type and ignores the others
In what organisms was the foraging theory tested?
Bluegill sunfish
How is the hypothesis that bluegill sunfish select prey so as to maximize their energy intake tested experimentally?
Provide bluegills with varying proportions of Daphnia of different sizes and densities, compare prey eaten with predictions of energy maximization hypothesis
What were the results of the bluegill experiment?
Bluegills did not take large prey selectively when they were scarce but did when they were common
Other than energy content, what can be important to some foragers?
Minerals
Give an example of an animal obtaining minerals.
Moose wade into streams and ponds to eat plants that contain more sodium than the terrestrial plants from which they get most of their energy
Why do animals ingest some foods for reasons other than energy or the nutrients they provide?
Provide poison
Antibacterial properties
Where do some species of frogs obtain the poison in their skins?
By eating certain species of ants that have evolved poisons (the frogs are immune to the poison)
What do spices contain?
Chemicals known to protect plants that produce them from bacteria and fungi
How was the antibacterial theory of spices tested?
By exposing food-borne bacteria to chemicals found in spices
What is an alternative hypothesis of human fondness to spices?
Spices disguise the smell and taste of spoiled foods, however this is not advantageous
What factors helps animals choose a mate?
Inherent quality of potential mate
The resources it controls (food, nest sites, escape places) or a combo of the two
Why are sexual roles in males and females so different?
Cost of producing sperm and eggs, males increase reproductive success by mating with many females, females have success by increasing quality of output
What do females cause by her choice among males?
The evolution of traits that reliably signal male quality
Give an example of a male using courtship behavior to signify that he is in food health/control resources/ good forager.
Hangingflies species court females by offering them dead insects- the bigger the better (the longer she copulates with him)
How must responses to the environment be?
Times appropriately.
What controls the daily cycle of behavior?
Circadian rhythms
What does the persistence of daily cycles in the absence of environmental time cues suggest?
Animals have an endogenous (internal) clock, known as circadian rhythms
What is it called when a rhythm is shifted?
Phase-advanced or phase delayed
What is the phase-advance/delay that occurs daily due to the circadian rhythm not being exactly 24 hours called?
The rhythm is entrained to the cycle of light/dark
What happens to an animal kept in constant conditions?
It will not be entrained to its environment, its circadian clock runs according to its natural period- it will be free-running
What control is the free-running circadian rhythm under?
Genetic control
Why do period lengths change?
Different among species
Mutations within species
In what animals have different sensory capabilities evolved in response to daily cycles?
Nocturnal and diurnal animals
In what two species can different sensory capabilities be seen due to being nocturnal and diurnal?
Diurnal ground squirrel’s retinas are made entirely of cone cells
Nocturnal flying squirrel’s retinas are made entirely of rod cells
What controls seasonal behaviors?
Photoperiod and circannual rhythms
What is the photoperiod?
Change in day length
What is photoperiod used for?
Reliable indicator of season to come
When is change in photoperiod not a reliable indicator?
Hibernators, bird overwintering near the equator
What do hibernators and birds overwintering have?
circannual rhythms
What are circannual rhythms?
Built-in neural calender’s that keep track of the time of the year
What are the three major ways that animals find their way around their environment?
- Piloting
- Homing
- Migration
What is piloting?
Orientation by landmarks/ knowing and remembering the structure of the environment
What species uses piloting?
Grey whales migrating between Bering Sea and coastal lagoons of Mexico
What piloting cues do grey whales encounter along the West coast of North America?
Coastlines, mountain chains, rivers, water currents, wind patterns
What is homing?
The ability to return over long distances to a specific location
How is homing accomplished?
Without visual cues- e.g. pigeons that were fitted with frosted contact lenses to see just the degree of light
What two types of navigation is used by animals migrating?
- Distance and direction navigation
- Bicoordinate navigation
What is bicoordinate navigation?
Also known as true navigation
Requires knowing latitude and longitude of current position and the destination
What animals are capable of bicoordinate navigation?
Gray-headed albatrosses which bread on oceanic islands and flies over southern oceans for 8-9 years before flying home when it reaches maturity
How do albatrosses fly back to their island?
Circadian rhythm gives information about time and position of the sun to determine their coordinates
How is the hypothesis that pigeons can determine compass direction from the position of the sun tested experimentally?
Place pigeon in a circular cage from which it can see the sky but not the horizon.
The pigeon can be trained to seek food from one direction even when cage is rotated between trials.
How else was the pigeon tested?
A bird is placed in an altered light-dark cycle to advance circadian rhythm 6 hours. When the bird is returned to natural cage, seeks food in the east.
What is the name of the way the pigeon orientated in the experiment?
Time compensated solar compass.
How do diurnal animals orientate at night?
The stars offer tow sources of info: moving stars and fixed point
How was it shown that birds can learn to use star patterns for orientation?
Raise young birds in planetarium, if star patterns are rotated to simulate Earth’s rotation, the birds could orientate inside the planetarium. Under non-moving sky, young birds did not orientate in any particular direction.
How do some animals orientate when it is overcast?
Magnetic sense
Pigeons ability to navigate is impaired if magnets are attached to their heads
What might be a mechanism behind the magnetic sense of some animals
Birds could use the polarization of light which can give directional information
When does the behavior of an individual become elaborated as a display or signal?
When the transmission of information benefits both the sender and reciever
How do male courtship displays benefit both sender and reciever?
- Male’s attractiveness is improved
- Female assesses the quality of the male
How do female red deer assess male fitness?
By listening to the loud vocalizations of competing stags- large, healthy males can sustain, weaker males lose.
What are the benefits of visual signals in communication?
-Rapid and versatile, easy to produce, indicate position of signaler
When is visual signaling not useful?
At night or in environments without light (caves, ocean depths)
What are the benefits of chemical signals?
Specific, information rich, durable
What is the name of molecules used for chemical communication between individuals of the same species?
Pheromones
Give an example of a species that communicates using pheromones.
Japanese silkworm moth
What do Japanese silkworm moth use pheromones for?
Male moths up to several km downwind determine that a female of their species is sexually receptive
What do pheromone messages left in the environment by mammals who mark their territories convey?
Species, individual identity, reproductive status, size, how recently in area
What are the advantages of auditory signals?
Can be used at night/dark, receiver does not have to be focused on signaler, long distances, go around objects, greater distances
What are some disadvantages of auditory signals?
Cannot convey complex information as rapidly as visual information
Give an example of an animal that uses auditory signals.
Humpback whales use complex songs which can be heard hundreds of km away- to locate one another.
What are the advantages of tactile signals?
Communicates complex messages
What is the best studied example of tactile signals?
Dance of honeybees
What type of dance does the honey bee do if the food is more than 80m away?
waggle dance
How is the waggle dance performed?
Forager bee repeatedly traces a figure of 8 pattern
The angle of the straight run indicates direction of food source relative to direction of sun, speed indicates distance (slower=further)
What dance does the honey bee do if the food is less than 80m away?
round dance
How is the round dance performed?
Run in a circle and reverse direction each circumference, odor on her body indicates the flower, the dance communicates the source is within 80m.
How do some species of fish communicate using electrical signals?
Generate electric field by emitting a series of electrical pulses. Used for sensing objects and communication
Give an example of a fish that uses electrical signals to communicate.
Glass knife fish
How do glass knife fish use electrical signalling?
Each emits a pulse at a different frequency that relates to its status in the population. (lowest frequency=dominant male, highest frequency=dominant female)
Where do glass knife fish live?
Murky water of tropical evergreen forest
When does social behavior evolve?
When cooperation between conspecific individuals achieve a higher rate of survival and reproduction
Give an example of group living leading to hunting success.
Human ancestor’s hunted in groups to kill large mammals they would have otherwise not been able to subdue
How was the hypothesis that flocking helps animals evade predators tested?
Release a goshawk near wood pigeons (in England), observe whether the hawk catches the pigeon
What were the results of the hawk/pigeon experiment?
The more pigeons in the flock, the sooner the hawk is potted and the lower the hawk’s attack success.
Why did the hawk’s success rate decrease with more pigeons?
Individuals spotted the hawk earlier and flew away- escape behavior stimulated others to take flight too
What costs are imposed on pigeons living in a group?
Interfere with their ability to find food
What is an almost universal cost associated with group living?
Exposure to disease and parasites
Give an example of family units that consist of older offspring helping parents.
Florida scrub jays- a breeding pair plus up to 6 helpers
What type of behavior does natural selection favor?
Altruistic behavior
What is altruistic behavior?
Behaviors that reduce helper’s reproductive chances but increase fitness of helped individual
Why does an individual helping relatives increase the representation of their alleles in the population?
Shares 25% alleles with siblings offspring
What does altruism contribute to?
Animals inclusive fitness
What is inclusive fitness?
Individual fitness plus fitness gained by increasing reproductive success of nondescendant kin
Give an example of a species that shows altruistic behavior
White-fronted bee eaters (african birds)
How do white-fronted bee eaters display altruistic behavior?
-Breeding pairs are assisted by nonbreeding adults who help incubate eggs/feed nestlings
When given the choice, who do nonbreeding bee eaters help?
The nest with young more closely related to them
What name is given to social groups who include sterile individuals?
Eusocial
When have eusocial groups evolved?
Termites
Hymenopterans (bees, ants, wasps)
When is eusociality favored?
When it is difficult/dangerous to establish new colonies
Where do most eusocial groups live?
Nests or burrow systems
Name a eusocial mammal group.
Naked mole rats
Why do some populations exclude newcomers?
Newcomers activities may lower quality of the habitat
How do some populations buffer fluctuations in food availability?
By storing food- within body (fat, starch), outside their body (seeds, spores, wood, fungi, leaves, nectar)
What does food choice influence?
Species composition and abundance of prey
What is the latin name of acorn woodpeckers?
Melanerpes formicivorus
How do acorn woodpeckers store food?
By drilling holes in dead trees to hoard acorns in
How was the theory that removal of the dominant species allows subordinate species to occupy that area, but removal of subordinate species has little effect on dominant species tested?
Artificial flower patches made from feeders
Hummingbirds
What are the two humming bird species in the study, and what do they weigh?
Blue-throated hummingbird (8.3g)
Black-chinned hummingbird (3.2g)
What happened when blue throated hummingbirds were absent? Present?
absent- black chinned fed at rich feeders
Present- black chinned fed at poorer-quality feeders.
What can social animals achieve?
Greater population densities
What % of individuals living in canopies of tropical forests are eusocial ants?
94%
How do ants influence the community of insects in tropical forests?
By protecting aphids to consume their anal drops
By eating other insects for protein
By driving away other predatory insects
