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Chapter 26 (Metapopulations in patchy environments (fugitive species…

- - - - a region of the enviro. is composed of discrete patched species live
      - some patches are occupied while others arent
      - empty patches will be occupied by migration from other patches
      - population in patches have a probability of going extinct
  - - - high quality patch
      - high emmigration rates
    - - low quality patch
      - high immigration rates
- - - - map out which herbivores consume most energy
      - trace energy flows through community
- - - - important in measuring diversity
      - how big an area
      - larger areas will be more diverse
    - - relationship between area and species richness
      - S=cA^z
        
        s= number of species
        
        A= area
        
        c and z are unknown constants
    - - plotting # of species in each abundance class
      - reflects a species individuals
      - doesnt reflect all individuals as equal
  - - - oldest and most commonly taught theory
        
        tropical regions near equator have benign environments
        
        short occasional dryness
        
        always warm
        
        constant rains
        
        those at higher lat. have more severe conditions
        
        have to adapt to freezing or water stress
        
        bitter temperatures
        
        permafrost
        
        brief and cool growing periods
      - geographical and geological theory
        
        high altitude in southern hemisphere
        
        very low diversity
        
        partially due to no ice free land
        
        tropical regions
        
        more land available for plants
        
        more land for all other organisms due to food sources
      - evolution
        
        50 million years ago earth climate started to change
        
        it got colder
        
        the land was still morphing
        
        continents still were shifting
        
        weather started getting cooler
        
        in order for plants to survive 12mya they had to evolve
        
        plants didnt have much time to adapt
        
        so fewer plants are adapted to cold dry weather
        
        causing diversity # changes in latitudes
        
        plants in temperate climates needed different structures
        
        needed to use day length to detect winter
        
        well-protected resting buds are needed
        
        doormant vascular cambium in winter
        
        storage organs
- - - - helps us understand how we should harvest
      - we harvest various preys- fish, deer, lumber, etc.
    - - predators feeding rate
        
        hunting time
        
        how fast they find prey individuals
      - handling time
        
        amount of time needed
        
        consuming prey
    - - functional response depends on prey density
      - feeding rate increases when prey increases
      - dN/dt = rN- aNP
    - - line indicating population stability
      - if pred. is sparser than line, prey increases
      - if pred. line is above line, prey is below
    - - may be an important factor
        
        could explain the loss of species diversity
        
        in an "improved" habitat
      - improving conditions for prey
        
        may lead to predator to over-exploit prey
        
        causing loss of both species
  - - - 3 factors are initially important
        
        probability of encounter
        
        rare species will be consumed less
        
        finding a specific individual
        
        camoflage and size are factors
        
        decision by predator
        
        decision to attack an individual once encountered
        
        is the prey poisonous or spiny?
        
        is it too small? or worth the trouble
        
        probability of being eaten
        
        is the fruit hard to crack open?
        
        optimal foraging
        
        examine interactions of these factors
        
        understand why predators eat what they do
        
        optimal diet model
        
        produced from optimal foraging
        
        model makes 4 predictions
        
        predators prefer higher energy prey
        
        will include lower energy prey if more abundant
        
        some prey will always be eaten others wont, regardless
        
        probability of one plant being eaten depends on other species factors
        
        is the prey hard to digest?
      - predators choice of prey
  - - - occurs when organisms consume shared resource
      - makes it less available for other organisms
    - - one organism restricts another organisms access to a resource
      - even though the first organism might not be using it
    - - when a species can increase from low population to high
      - even with the competitors present
    - - any substance/factor that can increase growth rates
      - as availability is increased
      - and that is consumed by an organism
- - - - alter small area of habitat immediately below them
      - more favorable soil for other species seedlings