PracticeMidterm2Key

PracticeMidterm2Key - Your name: _ EEB 122b SECOND MIDTERM...

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Your name: _____________________ Page 1 EEB 122b SECOND MIDTERM
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Your name: _____________________ Page 2 1. You are interested in conducting an experiment with two competing species of plants. Below are the zero-growth isoclines for the two species. a) Draw the vectors that describe how N1 and N2 change at points A, B, C, and D on the graph above. (4 pts) (One point per correct arrow) b) Is the competition coefficient for N1 ( 1,2 ) greater than, equal to, or less than 1? (2 pts) >1 c) Is inter- or intraspecific competition stronger for species 1? (2 pts) Inter d) If you planted many individuals of each of these species in a field together and observed the community over many generations, which of the two plant species (if either) would you expect to go extinct? (2 pts) The species that goes extinct will depend on the starting ratios of individuals. (But if you assume the two species are planted in equal quantities, species 1 will go extinct) e) Why? (2 pts) This interaction is an unstable equilibrium that will have a different result depending on the starting conditions. (If you assume the starting condition is an equally large number of each then species 1 will go extinct because the competition coefficients are not equal) C D
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Your name: _____________________ Page 3 2. During a survey conducted in October 2003, separate populations of a threatened endemic rodent species were found in each of several habitat patches around Lake Naivasha, Kenya. Each year storms flood burrows in an average of 40% of the occupied patches, causing local population extinctions. Despite the high level of disturbance caused by the storms, a survey conducted in October 2007 revealed that the rodent species has persisted in this region of Kenya. a) Describe how the rodent species may be able to persist in this region, despite frequent destruction of much of its habitat. (4 pts) There are high enough reproductive rates in the occupied patches and enough dispersal from patches that the destroyed habitat can be recolonized regularly b) Do these habitat patches constitute a metapopulation? (1 pt) yes c) Why or why not? (2 pts) There is regular gene flow between all the patches via dispersal d) What two major patch characteristics account for the colonization and extinction rates of local populations? (2 pts) Below is the life table of the rodent population found in one of the patches. x p x l x m x l x m x 0 0.1 1 0 0 1 0.8 0.1 4 0.4 2 0.5 0.08 4 0.32 e) Calculate R 0 by filling in the missing values in the table. (2 pts) R 0 = __0.72___ f) Is the population a sink or a source? (1 pt) Sink g) Why? (2 pts) R 0 <1, so the population is decreasing due to insufficient reproduction and survival rates to maintain the population
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Your name: _____________________ Page 4 3. Imagine a lake community consisting of algae, zooplankton (which eat the algae), and detritivores (or decomposers, which eat all dead material in the lake). a)
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PracticeMidterm2Key - Your name: _ EEB 122b SECOND MIDTERM...

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