Behavioral Ecology Flashcards
behavioral ecology
the study of how organisms respond to particular abiotic and biotic stimuli in their environment
study of behavioral interaction between individuals within populations and communities, usually in an evolutionary context
behavioral ecology in its broadest sense is the study of adaptations, and the selective pressures that yield them, in different ecological environments
Ernst Mayr
described two general categories of questions related to biological causation
proximate causation (how?)
understanding external and internal stimuli
ultimate causation (why?)
understanding value of behavior for survival/reproduction (fitness)
fixed action pattern
a highly stereotyped behavior patter that occurs in an invariant
e.g. jump-back behavior in kangaroo rats
optimal foraging theory
concept that animals forage in a way that maximizes the amount of usable energy they take
- energy of food item
- foraging time
- handling
- risk
fitness ∞ feeding efficiency ∞ benefits/costs
optimal foraging theory experiment with desert gerbils
optimal foraging with predators
trained old to fly over plots
-reduced foraging activity
presence of owls reduced foraging
but, increasing potential reward led to increasing foraging
calculate the actual predation risk (in terms of g of food)
marginal value theorem
optimal foraging model
assumptions:
- resources in discrete patches separated by areas with no resources
- travel time
- diminishing returns with time spent in patch
- individuals maximize rate of gain (prey items/time)
Anolis carolinensis/Anolis lizards
adaptive radiation-400 species
mainland and ectomorphs on Caribbean islands
breeding season in early spring
males
-establish and defend territories, display behaviors
females
-select among potential mates
Proximate causes (Anolis lizards)
increased production of hormones
- testosterone (males)
- estradiol (females)
triggered by:
- photoperiod- changes in day length
- social stimulation- male displays results in increased estradiol production in females
ultimate causes of Anolis male behaviors: sexual selection
Signals
dewlap extension and head bobbing are signals
-a behavior/characteristic that contains information that has been shaped by natural selection
information can be sex specific
Anolis signals
compress body
head bob/pushups
dewlap extension
chasing
fighting
holding a territory
sexual selection
natural selection on traits that influence the ability to obtain mates or choose good mates
dewlap extensions is for females and same with pushups for most part
territory
an area that is actively defended and provides exclusive or semi-exclusive use of resource
generalizations about escalated contests
displays tend to be honest signals of size and strength
displays involve a degree of coordination or even cooperation
often a predictable sequence of stereotypical behaviors of increasing intensity
honest signals
favored by selection on receivers
degree of coordination
common interest in obtaining information about each other
when not to fight
when there are axes of asymmetry between rivals
resource holding power
value of resource
ownership
resource holding power
when not to fight
one rival smaller/weaker
based on size/strength
value of resource
when not to fight
lower for one rival based on physiology, history, social status
e. g. one has mated with 10 diff female and the other has not mated this year
- the one that has bred has lest incentive to fight and may not want to risk it
ownership
when not to fight
non-owner less motivated to fight
the owner of the territory has put time and resources into holding the territory and doesn’t want to let that go to waste
fights are more likely if…
rivals are closely matched
stakes are high for both males
ambiguity about the relative status of rivals
migration
long-distance movement of a large number of individuals associated with a change of seasons
often coordinated with breeding and/or tracking limited resources
animal navigation
the ability of animals to accurately find their way to locations without instruments or maps
mechanisms:
piloting, compass orientation, true navigation
piloting
use of familiar landmarks
compass orientation
movement that is oriented in a specific direction
true navigation
ability to locate a specific place on Earth’s surface
bird navigation
birds have well developed navigation
migrating birds can travel hundreds or thousands of miles and return to the same place to breed
homing pecans moved hundreds of miles from their loft can return in a single day
proximate causes: visual landmarks, sun compass, star compass, geomagnetism
visual landmarks
birds routinely follow highways, railways, and waterways
many species follow coastlines
-results in high concentrations of birds where restricted corridors act as funnels
but birds that are blindfolded are still able to navigate
sun compass
first experimental studies in 1950s
starlings kept in round pavilions with and without windows
- during spring migration
- expected activity tour northwest
individuals must also have circadian clock to use a sun compass
internal clocks can be altered by manipulating light/dark cycles
birds with clocks shifted by 6 hounds shifted their orientation 90 degrees
star compass
many migrating birds fly at night and use stars to navigate
birds kept in cages in planetarium direct their activity in expected direction
-north in spring, south in fall
will also shift activity as predicted if stars in planetarium are manipulated
birds use more than just the North Star
systemic removal of different stars reveal that birds use multiple constellations
-redundancy useful during overcast nights
geomagnetism
experiments in 1970s showed that birds use geomagnetic field to navigate on cloudy days
-ring on head
proximate mechanism- leading hypothesis is vision-based system of detection
animal communication
process in which a signal from one individual modifies the behavior of a recipient individual
signal: info-containing behavior or characteristic
selection for signals with efficient transmission given the environment and physiology of receiver
- tactile signals for fossorial animals
- sound signals for aquatic animals
signal
information-containing behavior or characteristic
bee communication
Karl von Frisch hypothesized that bees communicate with dances
waggle dance encodes information on the direction and distance of a food source
- position of sun is also important
- still works on cloudy days because bees have UV vision
Karl von Fisch
hypothesized that bees communicate with dances
deceitful communication
signaler is attempting to exploit the receiver
e.g. hognose snake playing dead; fireflies flash the courtship signal of another species and then eat males that respond
success of deceitful signals is often frequency dependent
when honest signalers are most common
-natural selection favors individuals that are rewarded by behaving with normal response
when deceitful signalers are most common
-natural selection favors individuals that are able to detect and avoid/punish cheaters
altruism
behaviors that have a fitness cost to the individuals exhibiting the behavior and a fitness benefit to the receiver
includes:
cooperative breeding, food sharing, grooming, protection
evolution of as a paradox
3 ingredients of natural selection: variation, heritability, more offspring produced than can survive
outcome: traits of individuals with higher relative fitness increase in frequency over generations
thus, decrease of altruism alleles
3 ingredients of natural selection
variation
heritability
more offspring produced than can survive
variation
some individuals in population behave altruistically, other don’t
heritability
altruism behavior has genetic component; is heritable
more offspring produced than can survive
struggle for existence
kin selection
selection that acts through benefits to relatives at the expense of the individual
Hamilton’s rules (1964- William Hamilton)
model for the spread of altruistic allele
Br > C
B = benefit to recipient
r = coefficient of relatedness
C = cost of altruism
direct fitness: derived from generation offspring
since kin share alleles, the altruistic individual is
receiving a benefit through indirect fitness:
-derived from helping relatives produce more offspring than they would on their own
inclusive fitness = direct + indirect fitness
coefficient of relatedness
measure of genetic relatedness of two individuals
what proportion of genes are inherited from a common ancestor (0-1.0)
Probability of inheriting same paternal allele: ½ * ½ = ¼
Probability of inheriting same maternal allele: ½ * ½ = ¼
Total probability of inheriting
same allele: ¼ + ¼ = ½
Parent-offspring: 0.5 Identical twins: 1.0 Fraternal twins: 0.5 Siblings: 0.5 Half-siblings: 0.25 Grandparent-grandchild: 0.25 Cousins: 0.125
J.B.S Haldane
“Would I lay down my life to save my brother?
No, but I would to save two brothers or eight cousins.”
direct fitness
derived from generating offspring
indirect fitness
derived from helping relatives produce more offspring
than they would on their own
since kin share alleles, the altruistic individual is
receiving a benefit through indirect fitness
inclusive fitness
= direct + indirect fitness
helping non-kin
delayed direct benefits
reciprocal altruism
e.g. long-tailed manakins
helping non-kin example: long-tailed manakins males
long-tailed makings males cooperate elaborate courtship behaviors
-males are not closely related
alpha male gets about 99% of matings
why do beta males help?
solitary males do not attract females
-0 fitness
when alpha male disappears, a beta male inherits the display court
delayed direct benefit
reciprocal altruism
individuals act altruistically towards those that have helped them in the past or are likely to do so in the future
requirements:
- recognize each other
- repeated interactions
- memory of past interactions
e. g. vampire bats
- experiments show that food received (by donor in past) was best predictor of food donated
- more than relatedness
evolutionary game theory
game theory: study of mathematical models of cooperation and conflict
- developed in early to mid 1900s by economists
- many advancements by John Nash (Beautiful Mind)
applied to evolutionary biology in 1970s and later
John Nash (Beautiful Mind)
made many advancements to game theory
Prisoner’s dilemma
two members of a gang are imprisoned, kept apart
prosecutors lack evidence to convict a pair on principle charge
criminals given a choice:
- stay quiet (cooperate with accomplice)
- rat (defect)
if both cooperate: each serve 1 year if both defect: each serves 2 years if one cooperates and the other defects: defector set free cooperator serves 3 years (sucker’s payout)
golden balls game show
iterated prisoner’s dilemma
some players play multiple times
formally developed in 1980s
competition to develop computer model for best strategy
tit-for-tat model won (only 4 lines of code)
- cooperate on first interaction, then match opponents previous move
- allows for forgiveness and retaliation
- type of reciprocal altruism
behavior
action in response to a stimulus
learning
an enduring changing behavior that results from a specific experience in an individual’s life
innate behavior
is inherited–meaning that is is passed genetically from parents to offspring
fitness trade-offs
inescapable compromises between two traits that cannot be optimized simultaneously
cost-benefit analysis
a framework from economics borrowed by behavioral ecologists to understand and quantity the behavioral choices that animals make
foraging
when animals seek food
intersexual selection
sexual selection when female choose males
intrasexual selection
sexual selection when males compete with one another for mates
circadian clock
an internal clock that maintains a 24-hour rhythm of chemical activity
communication
any process in which a signal from one individual modifies the behavior of a recipient individual
a crucial component of animal behavior
eusociality
workers sacrifice most or all of their direct reproduction to help rear the queen’s offspring
as in bees
