Chapter 3.1 Ecological Succession

  • Ecological Succession:Natural, gradual changes in the types ofspecies that live in an area, the gradual replacement of one plantcommunity by another through naturalprocesses over time
  • Primary Succession:Begins in a place without any soil, starts with the arrival of living things suchas lichens that do not need soil to survive (pioneer species)
  1. Soil starts to form as lichens and theforces of weather and erosion help breakdown rocks into smaller pieces
  2. When lichens die, they decompose,adding small amounts of organic matter tothe rock to make soil
  3. Simple plants like mosses and ferns cangrow in the new soil
  4. The simple plants die, adding moreorganic material
  5. The soil layer thickens, and grasses,wildflowers, and other plants begin to takeover
  6. These plants die, and they add morenutrients to the soil
  7. Shrubs and tress can survive now
  8. Insects, small birds, and mammals havebegun to move in
  9. What was once bare rock now supports avariety of life
  • Lichens:The algal or cyanobacterial cells arephotosynthetic, and as in plants theyreduce atmospheric carbon dioxide intoorganic carbon sugars to feed bothsymbionts, the fungus provides support, water andminerals from the substrate for the algae
  1. Lichens help to break down hard substrate, providing nutrients to the soil
  2. When lichens die, they further help to create a nutrient rich soil
  • Secondary Succession:Begins in a place that already has soil andwas once the home of living organisms, occurs faster and has different pioneerspecies than primary succession
  • Climax Community:A stable group of plants and animals thatis the end result of the succession process (does not always mean big trees)

Chapter 4– Population Dynamics

  1. Population Growth

Population density = # of individuals in a given area

  1. J-shaped curve
  2. Exponential growth
  3. Unchecked growth (carrying capacity not met)
  4. S-shaped curve
  5. Limiting factors (Limit population growth)
  6. Food availability
  7. Disease
  8. Predators
  9. Space
  10. Carrying Capacity – the # of organisms that an environment can support indefinitely
  11. Births approximately equal deaths (zero population growth rate PGR)
  12. Overshooting carrying capacity results in limiting factors causing deaths to outnumber births
  1. Reproduction Patterns
  2. Rapid life history (e.g. mosquitoes)
  3. Rapid reproduction
  4. High number of offspring
  5. Small body size
  6. Organisms mature rapidly
  7. Reproduce early
  8. Organisms have a short life span
  9. Slow life history (e.g. elephant)
  10. Slow reproduction
  11. Low number of offspring
  12. Large body size
  13. Organisms mature slowly
  14. Reproduce late
  15. Organisms have a long life span
  16. Organisms tend to have parental care
  1. Density factors and population growth
  2. Density-dependent factors – affect populations more as the population size increases
  3. Disease (e.g. HIV)
  4. Competition
  5. Predators
  6. Parasites
  7. Food
  8. Density-independent factors – affect ALL populations, regardless of size
  9. Temperature
  10. Storms
  11. Floods
  12. Drought
  13. Volcanic eruption
  1. ORGANISMS INTERACTIONS LIMITS POPULATION SIZE
  2. Predator-prey relationship graph
  3. Predators affect prey populations
  4. Prey affect predator populations
  5. Intraspecific competition
  6. space
  7. food
  8. water
  9. reproduction

3. Crowding and stress - Stress symptoms include aggression, decrease in parental care, decreased fertility, and decreased resistance to disease

  1. chapter 4.2 Human Populations
  2. Demography – Study of human population size, density, distribution, movement, birth rates, and death rates
  3. Humans can alter their environment – eradicate diseases, created new food sources
  4. Calculating growth rate ( PGR = Birthrate -Death rate )
  5. Birthrate – number of live births per 1 000 in a given year
  6. Death rate – number of deaths per 1 000 in a given year
  7. Immigration – movement of individuals into a population
  8. Emigration – movement of individuals out of a population
  9. Doubling time – time needed for population to double in size
  10. Age Structure
  11. Stable growth – approximately the same number of individuals at each age grouping
  12. Rapid growth – a large proportion of the population is 19 years old or younger( more children than adults)
  13. Slow growth – a large proportion of the population is 55 years old or younger( more adultsthan children)