Study topics for test # 4

Test # 4 includes 2 take-home questions (click here to print out the take-home questions for test 4). You will need to bring the answers to take-home questions with you to the class and submit them together with the rest of your test. I will NOT accept them after I have walked out of the class on the test date. 

1. List and explain 4 major processes which contribute to the population dynamics (=changing population size). Give definitions of age and a cohort.
2. Define and explain dynamic and static survivorship in the population; give formulas. Be able to calculate dynamic survivorship if given number of individuals of a certain cohort in subsequent years (similar to the in-class example). Be able to calculate static survivorship from a graph of age distribution in the population.
3. Be able to calculate and fill out survivorship tables; explain and be able to calculate x, nx, lx, dx and qx in survivorship tables (similar to the in-class example).
4. Draw and describe different types of survivorship curves. Describe patterns of age-specific mortality in populations with Type I, II or III survivorship curve (which age groups have the highest, and which – the lowest mortality rates). Be able to construct (plot) a survivorship curve is given a life table of a population. Give examples of species that have different types of survivorship curves (name at least 2 species for each curve type).
5. Define overlapping and non-overlapping generations. Give examples.
6. Give formulas for calculations of net reproductive rate, generation time, geometric rate of population increase, and per capita rate of population increase. Be able to calculate these parameters if given a life table. Be able to calculate per capita rate of population increase if given: 1) net reproductive rate and generation time for a population with overlapping generations; 2) net reproductive rate for a population with non-overlapping generations; 3) geometric rate of increase of a population with non-overlapping generations.
7. Be able to determine from values of λ or r whether population is increasing, decreasing or the size is not changing.
8. Give formulas for geometric and exponential population growth. Which model is applicable for populations with overlapping, and which – for non-overlapping generations?
9. Be able to calculate population size at a given time t for exponentially growing and geometrically growing populations, if given per capita rate of population increase (or geometric rate of increase) and initial population size.

For example: 120 collared doves were introduced to England in 1960. What was the population size of the collared doves in England 5 years after introduction if per capita growth rate for this population is 0.5?

Answer: At t=0 (at introduction) N0=120 doves, at t=5 years N5=120*e^ (0.5*5) =1462 doves.

9. Explain how per capita rate of population increase and generation time are related to the body size of organisms. Which populations tend to grow faster – those of small organisms, or large ones?
10. Give formula for the change in population size for the logistic model of the population growth; explain each term in the model. What is K? Be able to determine K from the graph of increase in population size of logistically growing population. Be able to predict the direction of change in the population size (increase, decrease, does not change) if given values of population size N and carrying capacity of the environment for this population.
11. Explain which factors can limit population growth; give examples of density-dependent and density independent factors. Explain how density independent factors limit population growth of Galapagos finches. Explain how density-dependent factors can limit population growth of Canadian lynx.
12. Classify all possible types of interactions between species. Define mutualism, commensalism, competition and different types of exploitation (parasitism, herbivory and predation). Which types of interactions are positive (beneficial) for both species, which are neutral and which – negative? Which of these interactions are collectively called symbiosis?
13. Classify different types of competition by subject and by mechanism. Give definitions for interference and resource competition. Which of those types of competition implies resource limitation? Explain the difference between scramble and contest competition.
14. Explain how intraspecific competition results in density-dependent mortality and birth rate. How density-dependent mortality and birth rate determine carrying capacity of the environment? Be able to determine the carrying capacity of the environment from the graphs depicting density dependence of mortality and birth rate.
15. Explain the negative density dependence – Allee effect, and how it can lead to population extinction at low population densities. Be able to determine the critical population size for the Allee effect from the graph of density-dependent mortality and birth rate.
16.  Give examples of density-dependent mortalities and birth rates in natural populations of plants and animals. What is self-thinning in plants?
17. Define allelopathy. Explain how allelopathy can serve as a mechanism for competition in plants. Give an example of competition through allelopathy (European knapweed) and explain its physiological mechanisms. Is allelopathy resource competition or interference competition?
18. Describe Lotka-Volterra models for population growth under conditions of interspecific competition. Compare these models to the formulas of logistic growth of single populations. How is the presence of competitor reflected in the formulas for the population growth with competition? (NB You don’t need to memorize the equations for Lotka-Volterra models; I will give them to you on the test. But you need to understand what each term in the equation stands for).
19. Explain how population growth under Lotka-Volterra model depends on the values of competition coefficients α and β, and carrying capacity of each species K1 and K2. Be able to predict the outcome of interspecific competition if given values of α, β, K1 and K2 (these values can be provided to you either on a graph or as numbers).
20. Give an example of interspecific competition between two species of flour beetles, Tribolium castaneum and T. confusum. Explain how the outcomes of the competition depend on the environmental conditions under which these populations grow.
21. Define ecological niche of a species. Why is it often called an n-dimensional hypervolume?
22. Define and compare fundamental and realized niche of a species. How can you determine these niches?
23. Explain how competition can restrict ecological niche of the species. Use McArthur’s study of warblers as an example.
24. Define competitive exclusion and character displacement. Using an example of Darwin’s finches and an example from your take-home assignment to explain how character displacement allows species to co-exist and how it affects their realized ecological niches.
25. List 6 criteria (types of evidence) that needs to be provided to prove character displacement. Use the example of the ground finches to illustrate each of the 6 criteria.