Exam 3 Study Questions


Ch 10:

  1. You are studying a small rodent in a field system.  You notice that the rodent makes a similar type of call each day at the same time.  You are interested in knowing if this rodent is communicating or simply making a random noise.  What should you look for when the rodent makes this noise?


  1. In most cases of animal communication, the communication is not intentional (the animals do not think about the call) and the call does not convey any information about the external environment.  Describe two exceptions to this general rule in primates.


  1. Communication requires a signaler and a receiver, two individuals probably with different interests and needs.  What must be true of this interaction for communication to occur?  (Hint: 2 criteria must be satisfied)


  1. Scientists were long confused about how dominant Saddle-Backed tamarin females communicated with subordinate females so that the subordinates did not breed in this cooperative system.  What is the mechanism for communication in this system?


  1. In general, young birds do not over-exaggerate their food-begging calls although it seems as if natural selection should favor them doing so.  Why not?


Ch 11:

  1. Why do we question the evolution of sexual reproduction.  Clearly explain the cost of sex.


  1. Since the cost of sex is so great, why do most organisms do it?  Explain in lay terms the theories of Mueller’s ratchet and Environmental Unpredictability and how they might explain the evolution of sexual reproduction.


  1. What is ISOGAMY and ANSIOGAMY?  Give an example of an organism that is Isogamous and one that is Ansiogamous.


  1. Small gametes are much less costly to produce than large gametes.  Given this information, why are many organisms ansiogamous?  Why don’t we all produce small gametes?


  1. The sex that gives the majority of parental care to offspring generally becomes a limiting resource for the other sex.  Why?  After explaining that first statement, give an example of an organism that exhibits sex role reversal and explain why the roles are reversed in that case.


  1. What is the difference between Intrasexual and Intersexual Selection?  Why is Intrasexual selection so prevalent?


  1. Once again, we have discussed the topic of alternative mating tactics—you should be experts on this by now.  Think of the examples of jacks and parrs, streakers and large male fish.  What is necessary for the maintenance of alternative mating tactics?  Be able to explain the details of one alternative mating system!


  1. Sperm competition can be a tactic used in both Intrasexual and Intersexual selection.  Describe sperm competition in the two types of selection systems—How do males engage in sperm competition and how do females?  When do you predict sperm competition to evolve?


  1. When should a male guard his mate?


  1. Even when males are fighting it out for access to females, the females may have the last say in the matings and in the success of offspring.  Describe two ways that female engage in Inter-sexual selection and choose the best mates for the production of the best offspring.


Ch 12:

  1. Why was the documentation of widespread extra-pair copulations (EPC) in animals, especially birds, such a shocking discovery?  What does the frequent occurrence of EPC’s suggest about monogamous mating systems in general?


  1. Describe the four hypotheses for why females might engage in EPC’s?  Why is it difficult to distinguish which might be the primary force driving EPC’s.


  1. What is the difference between social and genetic monogamy.  What patterns of parental care may you expect to see in social versus genetic monogamy?


  1. Why is polyandry more common in birds than mammals?


  1. Polygyny is defined as a mating system where a male mates with more than one female but a female mates with only one male. Four different types of polygyny have been defined according to the distribution of females and other resources (food, territory).  What are the four types of polygyny and how do they differ in relation to the distribution of females and resources?


  1. You are a scientist studying a lekking species of bats in the tropics.  You are very interested in understanding whether this system is best described by the Hot-SPOT model or the Hot-SHOT model.  Design an experiment to test which model the bat lek fits best.


  1. Polygynandry, where several males form mating bonds with several females, is fairly common in the large, flightless birds such as South American Rheas.  What is driving this mating system?






Ch 13:

     1.  You are a scientist studying two previously un-described bird species in Amazonia.  One species appears to be a type of warbler (a small insectivore) while the other species is a type of sandpiper (a medium sized shorebird).  From your observations during the first nesting season, it appears that both warbler parents participate in the care of the young but only the male raises the sandpiper chicks.  What types of data would you seek to collect next season to determine the causes for the different parental care strategies?


  1. Lack’s hypothesis states that parents should lay just enough eggs to maximize the total number of surviving offspring.  Interestingly, most birds lay approximately one fewer egg per clutch than Lack’s hypothesis would predict.   How can you explain the difference between observed and actual clutch size?


  1. What is the Concorde Fallacy and how would you relate it to how males and females should make decisions on parental care investment?


  1. Using what criteria would you predict a male animal should provide parental care?


  1. Describe a scenario in which both parents might desert their offspring? 


  1. Interests of parents do not always equal the interests of the offspring, and vice versa.  Why is there a conflict between parents and offspring?


  1. The inevitable conflict between parents and offspring often results in offspring competing for resources.  In extreme cases of competition, sibilicide can result.  Describe and offer and example for the differences between “obligate” and “facultative” siblicide.


  1. What is kin selection?   How does Hamilton’s rule describe the occurrence of kin selection? 


  1. At first glance, the occurrence of brood parasitism seems a complete mystery.  With an educated eye, how would you explain why host parents don’t always throw out the eggs or young of the parasites.  (Hint:  I can think of at least 3 reasons).