Unit 3

• generalists: species that can adapt to and thrive in many different environments
• specialists: species that require specific living conditions to thrive
• K-selected species:

  • usually specialist
  • usually large
  • low reproductive rate
  • long life span
  • lives in stable environment (high competition)
• r-selected species:

  • usually generalist
  • usually small
  • high reproductive rate
  • short life span
  • can live in disturbed conditions (high competition)
• type I curve: high survival when young, low survival when old (ex. humans)
• type III curve: low survival when young, high survival when old (ex. frog, tree)
• type II curve: stable survival rate throughout life span (ex. bird)
• survivorship curve:

  
• late loss: a large % of the population survives from birth to death (type I)
• constant loss: death rate constant from birth to death (type II)
• early loss: a large % of the population dies early in life (type III)
• carrying capacity: the max # of organisms that an ecosystem can support without resource degradation
• biotic potential: the max reproductive rate under ideal conditions
• overshoot: when a population is larger than the carrying capacity of the environment
• dieback: when a population exceeds its carrying capacity, and then declines rapidly
• environmental resistance: factors that limit growth
• density independent factor: limits growth regardless of density, usually abiotic (ex. natural disasters)
• density dependent factor: limits growth as density increases, usually biotic (ex. disease, competition)
• logistic growth = limited resources

  
• exponential growth = unlimited resources

  
• fecundity: the ability to produce offspring
• population pyramid: a graphical representation of the distribution of a population's age structure (divided by gender and reproductive ability)
• pre-reproductive: 0-14 years old
• reproductive: 15-45 years old
• post-reproductive: 46-100+ years old
• growing population:

  • usually developing countries
  • low education
  • young workforce
  • more young people = more reproduction
  • ex. India
• stable population:

  • developed countries
  • high education
  • older workforce
  • people wait to have children
  • ex. USA, Canada
• declining population

  • developed countries
  • higher education
  • people wait long to have children
  • ex. Japan, Russia, Germany
• demographic transition model

  
• total fertility rate: the average number of children a woman has in her lifetime
• replacement rate: 2.1 children per woman
• developing nations have a high TFR
• developed nations have a low TFR
• Total Fertility Rate / TFR factors:

  • age of first pregnancies
  • educational opportunities
  • family planning
  • healthcare
  • gov policies (China’s “One Child” policy)
• less developed countries (LDC) = higher birth rates
• more developed countries (MDC) = lower birth rates
• higher education for women = lower total fertility rate
• doubling time: the amnt of time for a population to double
• rule of 70: calculates doubling time
• 70/r = doubling time 

  • (r = growth rate of a population)