Behavioural Ecology Flashcards
Four questions
Proximate cause: how a behaviour occurs (morphological and physiological mechanisms)
- mechanism: what stimulus causes the behaviour?
- ontogeny: how does an individuals reaction or response to the stimulus change over its lifetime?
Ultimate cause: why a behaviour occurs/why natural selection has favoured a behaviour
- adaptive value: what about the behaviour increases an individual’s fitness (helps it survive and reproduce)?
- phylogeny: what is the evolutionary history of the behaviour?
Behaviour
Action (stimulus-response) that alters the relationship between an organism and its environment
- stimulus may be external ( e.g. vervet monkey alarm)
- stimulus may be internal (hunger pains)
Innate behaviour
- inherited or inborn
- inflexible (i.e. not affected by learning or environmental conditions)
- stimulus triggers response automatically
- do not need be to taught these behaviours
Instinctual behaviour
- inborn/inherited
- inflexible (independent of environmental conditions)
- more complex than innate
- e.g. wildebeest calves stand ad walk immediately after birth
Condition dependent behaviour
flexible in response to environmental conditions/change response to environmental cue (i.e. spiny lobsters hide more when there are more predators)
- cost benefit analysis in behaviour (energetic, risk, & opportunity cost)
Learned behaviour
Changes in response to learning; learning is a change in behaviour that results from a specific experience in the life of an individual (e.g. grizzly bears teach clubs to fish)
Behaviour type matrix
Learnability (down) and condition dependence (right)
Genetic predisposition
A genetic characteristic which influences the possible phenotypic development of an individual organism within a species/population under the influence of environmental conditions
- rover allele (high population density)
- sitter allele (low population density/resource abundant; expends less energy)
Foraging behaviour
Depends on distance travelled
- min. cost of finding/ingesting food and risk of predation
- max. usebale energy then in
- farther away increases risk of predation
Darwinian fitness
Measure of the reproductive success (contribution to the next generation); has 3 components:
- Survival or mortality selection
- Mating success or sexual selection
- Family size or fecundity selection
Sexual dimorphism
Refers to phenotypic difference between males and females; in many cases dimorphisms cannot be explained by viability selection (selection of individual organisms who can survive until able to reproduce)
Sexual selection
Differential reproductive success resulting from differential abilities to find a mate; undergo different selective pressures
Parental investment
The energy, time, and resources devoted to mating, gestating, and caring for offspring; parental investment usually much greater for females; eggs are expensive and sperm is cheap
Daily energetic investment in gametes (m vs. f)
- daily female egg productions requires 3x the energy needed for daily basal metabolism
- daily male sperm production requires 4/1000 of the energy needed for daily basal metabolism
- eggs require more energy than sperm
Asymmetric limits on reproductive potential
Males have much greater variance in reproductive success than females (can produce an infinite quantity of sperm); but success is limited by the number of mates they can obtain
- male reproductive success diminishes with age; females does not
Intrasexual selection
Interactions between members of the same sex
Intersexual selection
Interactions between members of opposite sexes
“Male-male” competition: combat
- Intrasexual section is male-male combat can favour morphological traits (i.e. large body size, armour, antlers etc.)
- the greater the potential for reproductive success (variance) the greater the competition for mates
- when reproductive variance is greater for females, it will favour competitive traits
“Male-male” competition: infanticide
Male kills off other males young since nursing females are not able to breed
Estrus
Recurring period of sexual receptivity
Cues for mating
Males and females synchronize; reproduction synchronizes with food availability and predation risk
Seasonal cues: Day length triggers hormonal change in spring; phonology: study of seasonal timings in life cycle events
Social cues
Synchronizing
- widest selection of possible mates
- timed to coincide with abundance of resources
- timed to coincide with favourable weather
- cues result in resources when they’re most available
Female choice
Females have opportunity to choose which mate they want to mate with (will pick male that has the traits she is looking for)
- most fit; passes on to offspring
- mating calls, colours etc. proves how they acquired resources
HOW female chooses (female choice)
- good genes hypothesis: male ability to pass on genes that will increase survival/reproductive success of her offspring
- sexy sons hypothesis: male whose genes will produce male offspring with best chance of reproductive success
- sometimes random
Polygyny
Males mating with 2 or more females
Polyandry
Females mating with 2 or more males; males contribute significantly to parental care
Classic polyandry
Female has multiple males in the brood that each tend their own clutch
Cooperative polyandry
All males contribute to the parental care of a single clutch; some may not be his offspring but some are so he cares for them all
Diel migration
Move between 2 geographic regions daily (day and night); trade off between predator avoidance and food
Seasonal migration
Rainy vs. dry season; summer vs. winter
Navigation (migration)
- Piloting: familiar landmarks memorized
- compass orientationL ability to identify direction N,E,S,W (i.e. sun/stars, magnetic field, currents)
- true navigation: ability to locate a specific place on Earth’s surface
Why migrate? (risks & benefit)
RISKS:
- energy expenditure
- predation risk
- time not reproducing
BENEFITS:
- exploit temporarily available resources (food)
- access habitat only seasonally accessible
- avoid cyclic hazards (e.g. mosquitos and caribou)
- take advantage of different habitat during different life cycle stages
Migration
The intentional, directional often cyclic movement of a population between two regions, usually associated with a cyclic change in the environment
Dispersal
The movement of individuals in a population, typically from the area of birth to a new location (one way trip)
Communication
A social process in which a signal from one individual modifies the behaviour of another individual
- the stimulus is a signal and evokes a response in another individual; no response means no communication
Mimicry
Mimic colouration of another species to avoid predation; lying only works when it’s uncommon (i.e. lures)
Mimic males
Why aren’t all males mimics? Frequency-dependent selection.
- the mimic male will be more successful; will pass on genes and have offspring; but becomes too common then less effective (back-and-forth)
Altruism
Behaviour with a direct fitness cost to he individual carrying out the behaviour and a direct fitness benefit to the recipient (i.e. self-sacrifice); is rare
i.e. alarm calls (ground squirrels), worker casts (protect queen bee), food sharing (wild dogs)
Kin selection
Pass down your genetic info by producing offspring or by helping your relatives produce more offspring
- if benefits of altruistic behaviour are high, the benefits are dispersed to close relatives who likely also possess the trait for altruism
- if costs are low, alleles associated with altruistic behaviour will be favoured by natural selection
Hamilton’s Rule
If Br>C, then altruism is favoured by natural selection (look at example pg. 143)
B = the fitness benefit to the beneficiary
r = the coefficient of relatedness
C = the fitness cost to the actor
Hamilton’s rule: direct fitness
Derived from your own offspring (your own specific contribution to the next generation)
Hamilton’s rule: indirect fitness
Derived from helping relatives have more offspring than they could otherwise (contribution to relatives)
- affected by kin selection
- helping individuals in family increases chances of passing on genetics
Inclusive fitness
Direct + indirect fitness
Calculating coefficients of relatedness
rBC = sum of(rBA X rAC) (A, B, C are subscripts)
a) half siblings: r = 1/4
b) full siblings: r = 1/2
c) cousins: r = 1/8 (0.125)
Reciprocal altruism
An exchange of fitness benefit that are separated over time; not necessarily due to relatedness (may receive help in the fitter from non-kin)
Haploid
haploid male develops from unfertilized egg (no father but has grandfather); diploid female develops from mating of haploid female and diploid male
- diploid sisters: r = 0.75
- relatedness of diploid females to offspring: r = 0.5
