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Final Stuff, Behavioral Ecology, Population Ecology
Group of…
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Behavioral Ecology
Proximate Causation
Mechanism Mechanisms that are the reason for behavior
- Nervous system
- Hormones
- Genetics
Physiology
How behaviors are influenced by hormones, nerve cells & other internal factors
Ultimate Causation
Behavioral EcologyDetermines how behavior influences reproductive success or survival
- Reproductive strategies
- Altruism
- Group living & animal societies
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5 questions in behavioral ecology
- What to eat
- Who to mate with
- Where to live
- How to communicate
- When to cooperate
EatingOptimal foraging: animals maximize their feeding efficiency
- Risk of attack while eating
- How much energy is gained by eating
- How much energy it takes to eat & forage
Optimal foraging evolves through natural selection
- Natural selection will favor behavior that maximizes energy acquisition if the increased energy reserves lead to increases in reproductive success
- Avoid predators while finding food
- Optimal behavior has evolved by natural selection
- Female zebra finches that were successful foraging had successful offspring
- Removed offspring to ensure learning was not a part of the foraging success
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MatingHow does sexual activity occur (hormonal occur) Sex hormones increase during the breeding season
- Testosterone (males)
- Estradiol (females)
2 stimuli needed for hormonal changes to induce sexual behavior in females
- Breeding males
- Spring time
Cooperation
Altruism is flexible, condition-dependent behavior
Altruism: There is a fitness cost to the individual exhibiting the behavior, but a fitness gain to the recipient
Kin SelectionEvolutionary strategy that favors the reproductive success of an organism's relatives, even at a cost to the organism's own survival & reproduction
- Direct genetic advantage to altruism
- Natural selection will favor any behavior that increases the propagation of an individual's alleles
- Inclusive fitness (considers gene propagation through direct and indirect reproduction)
Alleles for altruistic behavior should rise in frequency when:
rB > c
Ex: Surrogate mothers would adopt related orphaned squirrel pups, but not unrelated organs in squirrels
r = coefficient of relatedness
B = reproductive benefit to recipient
c = reproductive cost to actor
Example
Surrogate mothers would adopt related orphaned squirrel pups, but not unrelated organs in squirrels
B = measured as the increased chance of survival of the orphan
c = calculated by measuring a decrease in the survival probability of the entire litter after increasing the litter by 1 pup
rB was greater than C - Females always adopted orphans
when rB was less than C - Females never adopted
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Living
Habitat Selection
- Juveniles disperse from natal ground
- How large a territory should be defended?
- How do habitat density & quality affect fitness?
Territorial behavior secures resources
- Home range: where the animal lives & forages; defends territory
- Defense against intrusion by other individuals
- Birds sing/display to signal their territory; energetically costly
- Benefit: increased food intake, access to mates, or access to refugees from predators
Migration & Navigation
- Orientation: follow a bearing (route from one place to another)
- Navigation: adjust or set a bearing using stars, sun, magnetic field
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Population Ecology
Group of individuals (of the same species) that live in the same place at the same time
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DemographyThe study of the number of individuals in a population. It depends on:
- Birth
- Immigration
- Death
- Emigration
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Community Ecology
A biological community consists of interacting species, usually living within a defined area
NicheThe way an organism "uses" resources or the environment
- Space it uses
- Food it eats
- Environmental conditions
- Temperature, moisture, etc.
- Best mating conditions
Resource partitioning
Some lizards live on the ground, others in the crown of the tree, and others on the trunk of the same tree
Fundamental Niche
The niche an organism can survive in.
Full range of conditions & resources than an organism could theoretically use in the absence of competition with other species
Realized Niche
The actual niche an organism occupies.
Actual range of conditions and resources that an organism uses
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Ecological Niche
Considers all abiotic factors such as pH, sunlight, moisture, salinity, and temperature