Midterm Flashcards
Proximate Analysis
Within a lifetime
Ultimate Analysis
Across Generations
4 Levels of Analysis
Proximate: Developmental, Mechanism
Ultimate: Evolutionary History, Adaptive Function
Essential for Natural Selection
Variation, Heritability, Differential Reproduction
Fitness Benefit / Costs
Mobbing in Gulls:
Costs-Time and energy, risk of injury
Benefit-Increased Offspring Survival
Lower predation in center of colony where mobbing is higher, hunting success more likely outside of colony`
Parsimony
the principle that, out of all possible explanations for a phenomenon, the simplest of the set is most likely to be correct.
Divergent Evolution
Shared ancestry common behavior
Convergent Evolution
Distinct ancestry common behavior
Rover vs Sitter Foraging Behavior
WT: 70%/30%
Rover ↑ fitness in crowded environment
Sitter ↑ fitness in less crowded
G x E
Gene-Environment Interaction (not nature vs nurture but both)
Linked by transcription, translation, influence on sensory systems, neural activity, brain
metabolism and so on
Interactive Theory of Development
development requires both genetic information and environmental inputs e.g. with worker bee development, as a bee’s behavioral phenotype changes from nurse to forager during her life, there must be changes in the interplay between genes and some aspect of the individuals environment
genes influence behavior & behavior can influence gene expression
Example of Environment Changing Gene Expression
Single Cohort Colonies in honey bees, where they will take on nurse/forager roles regardless of age
Differentiation in Gene expression in humans who identify as lonely and not
Migratory Routes in Black Capped Warbler
Strong genetic basis for migratory routes, when crossbred with individuals from different summer sites (
Main Themes of Behavioral Ecology
- natural selection will favors individuals that maximize their gene
contribution to future generations - how do trade-offs shape animal behavior
- how to resolve & avoid conflict, when to cooperate
- importance of ecological resources and conditions
Reproductive Success
Leaving copies of your DNA
Adaptive Value
Contribution to Fitness
There is no evidence of ______ selection
group
Selection occurs at the level of
the individual, but, good of the group=good of the species
Optimal Behavior and Trade-Offs
Maximizing surviving offspring in great tits, not just number of offspring produced. The more offspring, the lower the average weight of each individual, the greater the weight, the greater the chance of survival 3 months later
Cost Benefit Curve
Development
Learned through Trail and Error
Mechanism
- Sensory input induces neurons to direct muscles to hold
wings in this position
Evolutionary history
- Ancestral species fished this way
Adaptive
- Caught more fish and had more offspring
Observational Study
used to answer a research question based purely on what the researcher observes
Experimental Approach
the use of experimental methods in that study
comparative approach
the characteristics or the parts are compared across two or more research situations (like convergent and divergent evolution) (example of using all three approaches
Crow Whelk Dropping
After about 5 meters, dropping whelks has very little difference in breaking at higher height but it takes much more effort to fly that high
Eurasian Oyster Catcher
Small bivalves don’t have enough nutrients to offset the energy needed to find and break open bivalves, but they can’t open ones that are too big (30-50 mm is ideal)
Costs
: ex. energetic, risk, opportunity, time
Changes in environment (including internal state of the animal) will affect the
cost-benefit pay-offs
in variable environments animals prepare for risk
Red Queen Hypothesis
a species must adapt and evolve not just for reproductive advantage, but also for survival because competing organisms also are evolving.
Predation –
adaptations for predators & prey
- searching
- recognizing
- catching
- handling
Coevolutionary Arms Race
Predators- Selection for improvement in foraging
Prey-selections for improvement in defense
Predators and prey from same time should be most competitive
ex. Predator from Time B vs Prey from Time B
Predator or prey will have advantage when different times meet
ex. Predator from Time B vs Prey from Time C
Daphnia!
- Organism with dormant life stages
- Seeds, eggs, cysts, spores
preserved in sediments, ice - Can date specimens and compare
across time - Daphnia – water flea
- freshwater invertebrate
- eggs revived after 500 years!
Pasteuria ramose is their bacterial parasite
Sediment core from pond
* 39 years
* Measured infectivity rate
1. Contemporary (same layer)
2. Past (previous layer)
3. Future (layer above)
Crypsis
Prey
* Hiding, camouflage
* background matching
* disruptive patterns
* countershading
Polymorphism and search image experiment
Blue jays were trained to find one morph of underwing moths, moths on cryptic backgrounds were much much harder for the bluejays to locate than those on conspicuous backgrounds even when trained
HOWEVER, when only one type of morph was shown their identification skills improved with spotting them on cryptic backgrounds, but stayed the same when trained with a selection of morphs
Random mix of morphs,
interferes with ability to
form search image
negative frequency-dependent selection
the fitness of a phenotype or genotype decreases as it becomes more common. This is an example of balancing selection.
Countershading
a method of camouflage in which an animal’s coloration is darker on the upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and insects, both in predators and in prey.
When light falls from above on a uniformly coloured three-dimensional object such as a sphere, it makes the upper side appear lighter and the underside darker, grading from one to the other. This pattern of light and shade makes the object appear solid, and therefore easier to detect
Apostatic selection is
a form of negative frequency-dependent selection. It describes the survival of individual prey animals that are different (through mutation) from their species in a way that makes it more likely for them to be ignored by their predators
startle
suddenly displaying conspicuous eyespots or patches of bright and contrasting colours, so as to scare off or momentarily distract a predator
Masquerade
Look like an inedible object, twig, poop, leaf, etc.
With Naive chicks they gave them twigs, green, and brown caterpillars and they survived significantly longer on a branch than in an empty cage or on a branch with an altered color
Aposematism
Bright coloration associated
with repellants
* toxins, spines, stings
Mülllerian mimicry
a form of mimicry in which two or more noxious animals develop similar appearances as a shared protective device, the theory being that if a predator learns to avoid one of the noxious species, it will avoid the mimic species as well.
Like two different butterfly species where they mimic one another even though they each have three different morphs, each morph mimics the matching one in that range
batesian mimicry
resembling an organism that is toxic
or otherwise dangerous
Offspring recognition
Group/ colonial species are more likely to develop vocal and olfactory offspring recognition, which is costly but makes sure that you don’t take on extras, but there’s a risk of rejecting your own
(colonial cliff swallows with massive call differentiation in chicks compared to solitary barn swallows)
Solitary species are more likely to accept transplanted offspring but less likely to reject their own
What advantages are there to taking on someone else’s offspring
dilution effect and thermodynamic benefits
but only when the cost (provisioning offspring) is not too much
compare cost to accept with cost to reject
adaptive to accept if errors (brood parasites) are rare or cost to fitness is
low (as in precocial young)
Cost is may error and reject own offspring,
Interspecific “Code breaking”
exploiting fixed action patterns
Sign stimulus, innate releasing mechanism, fixed action pattern (brood parasite chicks make sign stimulus (begging chick with big red
mouth) exploit host parents innate fixed action pattern to feed chicks)
Humans can fake mole digging and get SO MANY WORMS, because vibration makes them leave the ground
Obligate brood parasites
- Do not build nests or care for young
- Only lay eggs in nests of other species
Common cuckoo specialized to parasitize reed warblers, cuckoos lay different types of egg and each female will specialize to a specific species depending on the color of egg that they lay
Mafia hypothesis
when a brood parasite discovers that its egg has been rejected, it destroys the host’s nest and injures or kills the nestlings.
Brown-headed Cowbird
generalist at species and individual level
non-evictor
brood parasitism persists
negative frequency dependent ESS?
Please ask Jesus and Sara what this means :(
Evolutionarily stable strategy (ESS)
a strategy (set of rules of behavior) that when adopted by a population (or
certain proportions of the population) cannot be replaced (bettered) by any
alternative strategy
Game theory
a quantitative approach to understanding why
behavioral variation exists.
payoff depends on what your competitor does
*Fitness is frequency-dependent
negative vs positive frequency dependent selection
Positive frequency dependent selection occurs when the more common a variant is in a population, the higher its fitness, while negative frequency dependent selection occurs when a variant has higher fitness the less common it is.
pure evolutionarily stable strategy (ESS)
– one strategy is always best
mixed ESS
average payoff for each strategy is equal at given proportions
mixed through genetic polymorphisms or individuals using mixed
strategies
hawk-dove strategies
Hawk is ESS if (V-C)/2 > 0 (i.e. V > C)
* Dove is ESS if V/2 > V (so Dove is never an ESS if V > 0!)
V = resource value
C = cost of fighting
ASK SARA Week 5 Monday
benefits of group living
- dilute risk of attack
- dilution effect
- swamping predators
- selfish herding
- predator confusion
- communal defense
- improved vigilance for
predators - food finding
- food capture
Costs of group living
o increased competition for resources (food, mates, etc.)
o attract more predators
o spread disease
Anisogamy
male and female defined by gamete size
o sex that invests more in offspring (gamete size, incubation/gestation, parental
care) becomes limiting and is choosey, other sex competes for mates
Operational sex ratio (OSR)
ratio of number of sexually receptive males to sexually receptive females in a
population, often more males
Parental care
females have larger gametes, more investment, more certain maternity (with
internal fertilization) = more likely to show parental care
o males have smaller gametes, less investment, less certain paternity, the
opportunity for much higher reproductive success = less likely to show parental
care
Intrasexual selection
o male-male competition
female defense polygyny
males fight for access to females
resource defense polygyny
males guard resources females need (often hold territories)
o sexual dimorphism, especially for size, weapons
o reproductive skew (stronger selection pressure on male traits)
size, dominance generally correlate with reproductive success
Intersexual selection
female mate choice
o sexual dimorphism for showy traits, ornaments, displays
o reproductive skew (stronger selection pressure on male traits)
what are females choosing?
Ex. widowbird
Ex. bullfrogs; inter- and intrasexual competition
Ex. lark buntings; female preferences can change
direct benefits
benefits to fitness via her own health or current effort
good territory, provisioning female or offspring
6
o Ex. hanging flies
