Study Guide for General Ecology (EEB 2244, Fall 2014).Note! Your preparation for the exam should be guided by these questions, but should notbe limited to it. For a good exam grade, study also your lecture notes and the lectures posted on the course web site, and re-read the assigned chapters from the textbook. The answers in parentheses (where given; if not given, then you can find answers in the lecture summaries) arenot complete, they are intended only as pointers to complete answers.Textbook chapters to study: 13, 14, 15, 18, and 19 1. Population dynamics. - Define population. - A group of individuals of one species living in a defined area- Boundaries of the area may be natural or arbitrary- Dynamical properties of population- Distribution and abundance - Which two aspects of population dynamics do abundance and distribution describe? (temporal and spatial)- Give an example of a modular organism. - Plants, fungi, sponges, etc.- reproduction due to production of modules (so it is difficult to define an "individual")- What are the ways in which we can quantify population size in modular organisms - Counting modules, counting genetic individuals, measuring biomass- Percentage cover (area) may be quantified rather than the number of individuals. EX: quadrant sampling- What three general distribution or dispersion patterns can be found in nature? - Depends upon distribution of resources as well as intraspecific competition- Uniform: Might occur in cases of territoriality.- Example: Golden eagle territories - Clumped: Most common, based on clumped distribution of desirable conditions or resources.- Example: Plantago, key host plant for Edith’s checkerspot, Euphydryas editha, requires serpentine soil that has a limited distribution on Jasper Ridge- Animal distribution may be based on particular physical conditions or on distribution of their food- Example 1: Human populations often near water- Example 2: Edith’s checkerspot distribution then follows the clumped distribution of Plantago (its food) - Random: Rare- Example 1: Spiders on the forest floor- Food and habitat is randomly distributed- Example 2: Desert plants (such as creosote bushes)- Severe competition for water keeps them spaced apart - What methods of control are currently used to suppress southern pine beetle infestations- Mechanical methods: salvage, cut and leave- disrupts ability to concentrate attack, treatments with inhibitory pheromones- How were southern pine beetles marked in the study that I described? - Sprayed with color?- What was the main conclusion of the mark-recapture study of southern pine beetle dispersal?-- What was the spatial scale of dispersal in bark beetles? In the experimental test of the area-wide effects of cut-and-leave, what was the experimental control?-- What is the main assumption about demographic rates used in deriving the exponential model? (per capita birth rate and per capita death rate are constants) -- What population dynamics are predicted by the exponential growth model? - If r>0, then population grows at an accelerating rate- if r<0, then population declines- if r=0 population stays constant- What is the shape of exponential growth when N is plotted on a logarithmically transformed scale?- Straight line- Understand the difference (and similarity) between the models of exponential and geometric growth.- Geometric Growth: has a constant rate change – increases per time period are constant 1, 2, 3, 4, 5 or 2, 4,6, 8- Applied when populations have discrete generations, we use capital R- Exponential Growth: rate change itself is increasing- ex:1,2, 4, 8, 16- Used when populations reproduce continually, we use small r- BOTH have the same shape when plotted as population (N) versus time (t)…bothhave “exponential” form.- When do we in practice observe exponential growth? - When population density is low, e.g. after a population release or invasion into anempty habitat. - How can the population dynamics of Michigan turkeys during the last three decades be described? - approximating exponential growth - How did we test that the population of Michigan turkeys grows exponentially?- By plotting the numbers on the log-scale- The logistic model: how does increased population density affect per capita birth and death rates? - fecundity declines, mortality increases - Explain the meaning of the two parameters of the logistic model. - What is the growth pattern predicted by the logistic model, when initial density is very close to zero? - Increasing?- What dynamics does the logistic model predict when initial population density is above the carrying capacity? - Draw a graph showing the trajectory of a population growing logistically from low N. - Draw two variants of the graph, one with non-transformed N on the y-axis, the other withlog-transformed N. - Give an example of a population growing logistically. - What were the dynamics of the reindeer herd on St. Paul Island? - First exponential growth, then population collapse caused by depletion of food. - Give examples of how dynamical patterns observed in nature can differ from the predictions of the logistic model. - Effects of environmental stochasticity introduce erratic movements of populationdensity; overshoots of the carrying capacity can lead to collapse or to population cycles; populations can decline to extinction2. Trophic interactions - Know the classification of pairwise interactions by the direction of effects on Species 1 on Species 2 - trophic, commensalism, mutualism, competition- What is the simplest possible trophic chain? - Two species in which one eats the other- Give an example of a trophic chain having three links- plant−herbivore−carnivore - What is a trophic web? - interconnected food chains showing who eats who in the community- What does the Australian example with the sheep fence illustrates? - That predators – dingoes – can have a drastic effect on population density of prey– red kangaroos- What are the four functional classes of consumers? - parasitoid, parasite, predator, grazer- How are they distinguished from each other? - on the basis of intimacy and lethality- Name some adaptations of prey to reduce predation risk. - Explain the difference between Batesian and MIllerian mimicries. - Give some examples of why it may be advantageous for prey to aggregate in groups- predator confusion, group vigilance, and group defense- Explain W.D. Hamilton’s idea of “selfish herd”. Explain