Zoology 441
Practice questions: metapopulations

1. The number of individuals present in an equilibrium metapopulation depends on the balance between two processes.  What are these processes?
2. Distinguish between an equilibrium and a non-equilibrium metapopulation.  Explain what is at equilibrium in an equilibrium metapopulation.  What aspects about the habitat in which animals occur and the behavior of animals may affect whether metapopulation is an equilibrium or a non-equilibrium metapopulation?
3. Distinguish between a classic and a mainland-island metapopulation
4. If you observe that animals of some species occur only in certain habitat patches, and do not observe animals of this species in other habitats, does this mean that each habitat patch is a deme, and that it is appropriate to use a metapopulation approach to study this species?  Why/ why not?
5. To study metapopulations, it is necessary to be able to describe potential habitat patches even if they are not currently identified by populations.  Use the studies of the skipper butteryfly (Hesperia comma) and checkerspot butterfly (Euphydrias editha bayensis) mentioned in Thomas and Hanski (1997; bottom of p. 361) to illustrate the care with which this must be done and the kinds of factors that must be considered.  There is bound to be some error in identifying habitat patches when they are empty, but Thomas and Hanski argue (bottom of p. 363) that it is a minor issue for butterfly studies.  What evidence from ecological experiments do they present to support the hypothesis that there are empty habitat patches for butterflies?
6. What are the four main causes of local extinction?   How does each contribute to local extinction.
7. Loss of genetic variation can potentially lead to local extinction, but has been argued as taking a long time and is not considered in the butterfly studies reviewed by Thomas and Hanski (1997).  Does the fact that it does not seem to be important for butterflies mean that loss of variation is not important for local extinction in other species?  What kinds of species might be more susceptible to problems associated with loss of variation than are butterflies?
8. What two processes result in an "extinction vortex?"  How do they affect each other?  How does the occurrence of extinction vortices depend on population size?
9. What can biochemical techniques such as starch-gel electrophoresis of proteins or use of RFLP's to study DNA tell us about dispersal behavior?  Why might this be important to studying metapopulations?
10. Suppose dispersing individuals of a species of lizard only disperse to areas that already contains their own species of lizard.  How will this behavior affect the probability of recolonization after local extinction?  How does this affect metapopulation stability?
11. Give reasons why animals disperse.  How would they affect recolonization and local extinction?
12. Discuss evidence from that butterfly recolonization depends on distance from patches with butterflies based on (a) studies of entire networks of empty habitat patches available for colonization existed, and (b) deliberate release of a species in a new region, as described on p. 367 of Thomas and Hanski (1997)
13. On page 374 of Thomas and Hanski (1997), they state that in a previous study, they had "assumed, with misgivings, that a constant proportion of individuals emigrates from each local population."  Has more recent research validated this assumption or does it suggest that some populations have higher proportions of immigrants than do others?
14. On pp. 379-380,, Thomas and Hanski (1997) present four reasons for considering variation in habitat quality when considering metapopulation dynamics.  What are these four reasons?
15. On pp., 380-381, Thomas and Hanski (1997) define something called a "pseudosink."  What is the difference between a source, a sink, and a pseudosink?  Why are source populations considered important for metapopulation persistance?  Would a source, a sink, or a pseudosink be most resistant to extinction during an extreme environmental event? Why?
16. Suppose you are studying a population of black-footed ferrets (assuming such a population existed) on a biological station.  Why might you need to know whether this was a source population or a sink population?  How would you determine whether or not the population was a sink population?
17. If b<d in a sink population, why doesn't the population eventually go extinct?
18. Give a situation in which the fundamental niche of a species is actually smaller (includes a narrower range of factors) than does the realized niche of that species.
19. Someone has done a study on the habitat requirements of an endangered species of darter by describing in detail the conditions within which this darter occurs within a local river system.  What problems might they have if they use this information to develop conservation guidelines but do not know if their population was a source or a sink?