population ecology

• biotic factors

  living organisms that can be harmful or helpful to others (bacteria, animals, protists, etc)
• abiotic factors

  nonliving aspects of the environment that affect organisms (temperature, light, air, etc)
• ecology

  study of the relationship of organisms to one another and to the environment
• population

  all the individuals of the same species that live and reproduce in a particular place
• population demographics

  geographical range, size, density, distribution
• geographical range

  • area over which a population is spread
  • changes depending on season, resources, and interspecies interaction
• population size

  • number of individuals of all ages alive at a particular time in a particular place
• population density

  • number of individuals per unit area (population size/range size)
  • changes based on population size and available habitat
• population distribution: how individuals are organized within a range
• clumped distribution

  formed by species that live in groups or when resources are limited/clustered
• random distribution


  formed by stationary species environments where resources are evenly spread
• uniform distribution 


  less common, occurs when resources are limited but space from other is advantageous
• exponential growth


  growth rate is constant, typical of small populations with abundant resources
• logistic growth


  growth slows as population size gets closer to carrying capacity
• carrying capacity (K)


  max number of individuals a habitat can sustain without degrading the environment ( determined by: resources, habitat, interaction with/other species)
• age structure


  number of individuals within each age group of a population
• survivorship


  proportion of an initial cohort that survives to each successive stage of life cycle
• metapopulations


  large population made up of smaller populations linked by occasional movement of individuals among them along corridors

  occurs when habitat is patchy
• R strategist


  species that produces large numbers of offspring but provides few resources for their support
• K strategies


  species that produces relatively few young but invests considerable resources into their support
• type 1 survivorship


  most offspring live full lifespan
• type 2 survivorship


  offspring die through out lifespan
• type 3 survivorship


  most offspring die young