Ecology- conditions

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Ecology- conditions
2010-03-01 21:58:16
conditions growth models

conditions, growth models
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  1. what drives variation
    • latitude: causes incident radiation and seasonality
    • timing and strength
    • uneven heating causes wind
  2. hadley cells
    • movement of air (and rain) due to earths rotation
    • affects climate in different areas
  3. biome
    • characteristic types of vegetation found across earths surface
    • dictated by climate- temperature and precipitation
    • latitude, weather patterns, ocean currents, topography all affect biome location
  4. variation in terrestrial conditions
    • direction surface faces
    • slope (amount of rain that soaks in, water storage)
  5. albedo
    • refelection of a surface
    • high: reflective (water, snow, ice, light colors)
    • low: dark colored, forests
  6. size of soil particles
    • bigger: causes lots of pores which allow water to move thru
    • smaller: holds water in
  7. human activities
    • gravel road (base components affect acidic environment)
    • impermeable surfaces (roads)
    • irrigation
    • CO2 concentrations
  8. ecological niche
    • summary of all the resources requirements and condition tolerances of a organism
    • bounds on where an organism cal live, grow, and reporduce
  9. population ecology
    studies what determines the distribution and abundance of populations

    • determine sustainable harvest levels
    • minimum populations sizes for threatened and endangered species
    • control of pests

    birth, death, immigration, emigration
  10. exponential growth
    constantly accelerating or decelerating

    each individual is predicted to add same number of new individuals (or lose)

    per capital growth rate is constant
  11. genomic growth equation
    • used to predict the change in size of a population growing exponentially, when individuals only reproduce only at a specific time each year (discrete breeding)
    • generations do not overlap

    generates periodic estimates of population size

    N(t) = N(0) Yt

    Its the RATIO thats constant, not the number added or lost from population
  12. exponential grown equation
    used to predict the change in population size growing exponentially when individuals reproduce continuously and the generations overlap

    Nt = N0 x ert

    generates instananeous estimates of populations size

    r = instantaneous per capita rate of population increase

    N(t) = N(0)ert

    • dN/dt = rN
    • dN/dt = net rate of population change, rate at which the size of the population as a whole is changing at a given instant in time, slope of line tangent to anywhere on the curve

    Nt = N0 x ert

    r = lnY

  13. equations
    • curves predicted by both models are unchanging thru time
    • due to per capita rate of increase or decrease is unchanging
    • biological processes contributing to population growth are unchanging too (birth, death, immigration, emigration)
  14. matrix modeling
    • another method to predict population growth, based on geometric
    • more detailed: focuses on survival and reproduction of different stages of an individual (age, size, dev. level)
    • transition probabilities: likelihood of each possible transition between 2 categories

    • 2 field seasons
    • year 1: assign stages and count number in each
    • year 2: determine probability of transition by comparing 1st year to 2nd year

    • stages based on biomass (plant size)
    • models run until population is stabilized and lambda is calculated
  15. native

    • native: evolved within a given geographic area
    • exotic: evolved outside a given geographic area
    • invasive: rapidly spreading, dominates areas into which is spead
    • non-invasive: not rapidly spreading
  16. invasibility
    ease with which a new species enters a community

    Edge vs intermediate vs center plots represent invasion, growth and today,
  17. biological control
    introduction of natural enemies from an invasive exotic species native range to control the invaders population in a new area

    controversial- expense, lack of effectiveness, bad outcomes
  18. Matrix model: lambda equations
    Y = N(t+1)/N(t)

    • Y >1 : population increasing
    • Y < 1 : population decreasing
    • Y = 1 : constant

    when Y stabilizes Y = N(t+1)/N(t) is the same from timepoint to timepoint

    model uses same transition likelihoods. biology driving population to increase or decrease is not changing
  19. density dependent factors
    • things that take a bigger percentage cut out of larger populations
    • must decrease reproduction/immigration, or increase death/emigration
    • intraspecific competition is big factor
  20. intraspecific competition
    • use or defense of a resource by one individual that reduces the availability of that resource to other individuals
    • same species (have same needs)
  21. compete for
    food, nutrients, water, oxygen, space, structures
  22. why competition harms individuals
    • might be unable to get limiting resources
    • must look harder and further, energy expense
    • increase stress (defending territory, aggression to individuals)
  23. slows down population growth rates at high densities
    • predators (as prey increase, predators eat them)
    • parasites
    • disease (higher density, increase disease)
  24. density dependence vs. density independent
    • density dependence: negative (population increases, growth rate decreases)
    • postiive (small populations, panda)

    • density independent: effects population regardless of size, based on proportion, no logistic growth