Populations Study Guide (KEY) 1. Define Population. All the members of a species living in the same place at the same time. 2. List and explain the three terms that describe population. a. Size. How large the population is b. Density. Number of individuals per unit area or volume. c. Dispersion. How the individuals are spread out. 3. What are the 3 types of dispersion? Random, clumped, even. 4. What is growth rate? Birth rate Death rate a. How can you have positive growth? BR > DR b. How can you have zero growth? BR = DR c. How can you have negative growth? BR < DR 5. What is biotic potential? The fastest rate at which a population can grow.
6. What is reproductive potential? The maximum number of offspring that each member of the population can produce. 7. What are three factors that affect reproductive potential? Multiple offspring at the same time, reproduce more often, reproduce earlier in life. a. Which of these has the greatest affect? Reproducing earlier in life. 8. What is exponential growth and when does it occur? Fast growth of a population. Occurs only when populations have plenty of food, space, no competition or predators. 9. Explain logistics growth and how it differs from exponential. Exponential Growth - without bounds, assuming they have plenty of resources. Logistics Growth - have limiting resources that stop the growth of a population. 10. Explain overshoot and die-off. Overshoot: The population numbers shoot up and go above the carrying capacity numbers. Die-off: The population goes down due to lack of resources and population numbers drop below the carrying capacity numbers and the populations begins to get smaller and dieoff.
11. Be able to interpret a graph of populations. Predator vs Prey graph. 12. Why do populations change over time? Resources depleted Deaths increase or Births decrease, natural selection. 13. What is carrying capacity? The maximum population that the ecosystem can support indefinitely. 14. Other than carrying capacity, what other factors can limit the growth of a population? Limiting resources and completion. 15. What are some examples of resources that could determine the carrying capacity of an ecosystem? Sunlight, water, food, amount of soil, etc
16. Explain the difference between K-Selected and r-selected species. K-Selected Species: Low r intrinsic birth rate, large organisms, few offspring, provide a lot of parental care, slow population growth (Stops at carrying capacity. R-Selected Species: High r intrinsic growth rate, many offspring, reproduce often, little to no parental care. generally not near k carrying capacity). 17. Explain the difference between density dependent and density independent regulations. Density dependent regs depend on how tightly crowded individuals are in an area. Density independent regs do not depend on the number of individuals. 18. In what ways are disease and predation density dependent? Increased physical contact and waste products mean that disease could spread easily. Dense prey populations make it easier for predators to find prey. 19. Define the following: a. Niche - Role of a species in an ecosystem b. Habitat - Area where a species lives c. Territory - An area defended by one or more individuals against other individuals.
20. Complete the following table on species interactions: Interaction Species A Species B Description Competition Harmed Harmed Negative effects to both Predation Harmed Species A feeds on B Parasitism Harmed Species A feeds on B Mutualism Both species are helped. Birds on rhinos. Commensalism Neither Species A is helped but B is neither helped nor harmed. 21. Explain the difference between direct and indirect competition. Direct is at same time. Indirect is at different times. 22. Define symbiosis and coevolution. Symbiosis- relationship where two species live in close contact. Coevolution- symbiotic species that evolve adaptation that reduce the harm or improve benefits.