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Final Stuff, Behavioral Ecology, Population Ecology Group of…

- - - - Balance between signals that evolve under natural & sexual selection
      - Deceitful signals are used in predation & mating
  - - - Altruism: There is a fitness cost to the individual exhibiting the behavior, but a fitness gain to the recipient
        
        Kin Selection
        Evolutionary 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
      - Reciprocal Altruism: altruistic behavior among non-related individuals
  - - - 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
    - - Homing experiments show that birds can find their nest after being displaced
        True for other animals
- - - - Distribution of organisms at the local scale:
        Random, Uniform, Clumped
        
        Uniform
        
        Competition will create a more uniform distribution
        
        Territoriality (establishing & defending a territory) will create a more uniform distribution
        
        Clumping
        
        Sociality
        
        Resource distribution
        Resource distribution is usually not uniform, so neither is organism distribution
        
        Predation
        (safety in numbers; group avoidance)
        
        Random
        
        Random distributions are rare
- - - - If r is positive, then the population is: increasing
        If r is negative, then the population is: decreasing
      - Changes in population size result from 2 factors:
        
        Density dependent
        Depends on density
        
        Logistic Growth
        The population growth rate gets smaller & smaller as population reaches maximum & is limited by resources in the environment (carrying capacity)
        
        Carrying Capacity
        Maximum number of individuals that can be supported by the place
        
        Depends on the # of individuals in the population
        If there are too many individuals, then death rate will increase faster than new individuals are born
        
        Growth is often density dependent
        
        When there is NO more space, the death rate > birth rate, r will decline
        
        Density independent
        Does not depend on density
        
        Exponential Growth
        If r is positive and constant, the population will grow exponentially (no limit to how big a population can get)
        
        Doesn't depend on the # of individuals in the population
        
        Observed naturally in 2 circumstances:
        
        A few individuals found a new population in a new habitat
        
        A population has been devastated by a storm or some other type of catastrophe & then begins to recover, starting with a few surviving individuals
        
        Population size increases until it reaches a carrying capacity
  - - - Survivorship Curves
        Populations cycle in number (up, down, up, down)
        
        Type I
        Survivorship throughout life is high, and most individuals approach the maximum life span of the species
        Humans have Type I curve
        
        Type II
        Most individuals experience relatively constant survivorship over time
        Songbirds have Type II curve
        
        Type III
        High death rates early in life, with high survivorship after maturity
        Many plants have this curve
    - - Human populations
        Growth rates differ among regions of the world
      - Growth depends on the number of reproductive individuals
      - Zero Growth
      - Negative Growth
      - Rapid Growth
    - - Fecundity
        The # of female offspring produced by each female in the population
      - Age-specific Fecundity
        The average # of female offspring produced by a female in a given age class (group of individuals of a specific age)
- - - - Species Interactions
        The realized niche will depend on these species interactions
        
        Interactions affect the distribution & abundance of a particular species
        
        Species act as agents of natural selection when they interact
        
        Effects on fitness
        (+) = positive effect
        (-) = negative effect
        0 = no net effect for individual
        Species 1/Species 2
        
        Predation
        One organism eats another one
        
        +/-
        
        Herbivory
        The consumption of plant tissues by herbivores
        
        +/-
        
        1 more item...
        
        Predation
        The killing & consumption of most or all of the prey individual by a predator
        
        Natural selection favors traits that allow an individual to avoid being eaten
        
        3 more items...
        
        Parasitism
        Benefits one species at the cost of the other
        
        +/-
        
        Parasite exerts selection in 2 ways:
        
        Appearance
        
        Behavior
        
        Competition
        Lowers the fitness of all individuals involved either:
        
        Uses energy resources needed for survival & reproduction
        
        Death/injury
        
        Interspecfic & Intraspecific
        
        -/-
        
        Competitive Exclusion Hypothesis
        "competitors cannot co-exist"
        
        Symmetric Competition
        Same fitness
        
        Asymmetric Competition
        Varying fitness
        
        Competitive exclusion occurs when competition is asymmetric
        
        Fitness trade-offs
        No one organism is superior in all aspects of living. Could be good at competing for space, but less good at enduring droughts, disease, etc.
        
        Every individual has a restricted amount of time & energy at its disposal (its resources are limited)
        
        A female can maximize fecundity, maximize survival, or strike a balance between the 2
        
        1 more item...
        
        Mutualism
        
        +/+
        
        Flowering plants & pollinators
        
        Mycorrhizal fungi & plant roots
        
        Farmer ants & fungi
        
        Crematogaster ants & acacia trees
        
        Cleaner shrimp & fish
        
        Commensalism
        One species benefits but the other is unaffected
        
        +/0
        
        Co-evolution
        Two species evolve in response to the pressure exerted by the other
        
        The outcome of interactions among species is dynamic & conditional