Ecology

Ecology

1. The study of interactions between and among organisms and their environments (Interaction b/w biotic & abiotic factors)

2. Level of Ecology

   • Bioshphere
     • The Sum total of living things on earth and the areas they inhabit
   • Ecosystem
     • A functional system consisting of a community, its nonliving environment, and the interactions between them
     • Studies living and nonliving components of systems to reveal patterns
       • Nutrient and Energy Flows
   • Community
     • A set of populations of different species living together in a particular area
     • focuses on patterns of species diversity and interactions
   • Population
     • A group of individuals good a species that live in a particular area
     • Investigates the dynamics of population change
     • Show characteristics to help predict their dynamics
       • Population Size
         • number of individual organisms present at a given time
           • can increase, decrease, cycle or remain the same
       • Population Density
         • number of individuals in a population per unit area
         • high density
           • Easier to find mates
           • increased competition
           • Increased transmission of disease
         • Low density
           • harder to find mates
           • plentiful resources and space
       • Population Distribution
         • Spatial arrangement of organisms
           • Random
             • No pattern
           • Uniform
             • Territoriality, competition
           • Clumped
             • arranged according to availability of resources
             • Most common in nature
     • 4 factors of population change
       • BIrth Rate
         • # births per thousand
       • Mortality
         • # deaths per thousand
       • Immigration
         • arrival of individuals from outside the population
       • Emigration
         • Departure of individuals from the population
     • Population Growth Rate
       • = (birth + Immigration) - (Death + Emigration)
       • Exponential growth
         • unregulated population increase by a fixed percent
         • Cannot be sustained indefinitely
         • Limiting & Carrying Capacity
           • Limiting Factors
             • Physical, chemical and biological attributes of an environment
               • Restrain population growth
           • Carrying Capacity
             • Max population size of a species that its environment can sustain
           • Limiting factors slow and stop exponential growth
             • S-Shaped Curve
   • Organism
     • An individual living thing
     • Niche
       • organism's use of resources
       • Specialists
         • narrow niches and specific needs
       • Generalists
         • Species with broad niches

3. Habitat

   • Environment where an organism lives
     • living & nonliving elements
   • They vary:
     • body size + needs
     • different needs at different times
     • Criteria to select habitat:
       • Soil, topography, vegetation, other species
       • Water temperature, salinity, prey
   • Species survival depends on it