Deck 7: Sexual Selection

Question 1

Sexual imprinting occurs when:

A) young animals learn what constitutes an appropriate mate from observing adults.
B) young animals copy the mate choice decisions of same-sex adults.
C) young animals are taught by adults to prefer certain traits in individuals of the opposite sex.
D) males learn which types of nuptial gifts are attractive to females through trial and error.
E) the development of mate choice preferences is shaped by genotype alone.

Answer 1

young animals learn what constitutes an appropriate mate from observing adults.

Question 2

Which of the following examples is inconsistent with females receiving direct benefits via mate choice?

A) Females choose males possessing nests that provide safe haven.
B) Females choose males that provide large nuptial gifts.
C) Females prefer males that demonstrate superior foraging abilities.
D) Females prefer males that are better able to deter neighboring males that may harass the female.
E) Females choose males with low levels of fluctuating asymmetry.

Answer 2

Females choose males with low levels of fluctuating asymmetry.

Question 3

Intersexual selection is to intrasexual selection as:

A) mate choice copying is to runaway selection.
B) female mate choice is to male-male combat.
C) male-male combat is to sensory exploitation.
D) handicap principle is to female mate choice.
E) good genes models are to sensory exploitation.

Answer 3

female mate choice is to male-male combat.

Question 4

Zahavi's handicap hypothesis suggests that females:

A) choose males based on the extent to which direct benefits are received.
B) do not benefit (directly or indirectly) from making mate choice decisions.
C) dismiss males that demonstrate the ability to survive with elaborate traits.
D) use traits that are honest indicators of male quality when choosing mates.
E) base their mate choice decisions on a male's ability to attract other females.

Question 5

Which of the following is NOT associated with sensory exploitation hypotheses of female mate choice?

A) phylogenetic analyses
B) long-term maintenance of female mate choice
C) hypothesis regarding the origin of female mate choice
D) males capitalizing on the preexisting sensory biases of females
E) assessing mate choice preferences in many related species

Question 6

Cross-fostering experiments are most useful for examining:

A) how certain genetic crosses influence behavior.
B) the effects of specific genes on the development of behavior patterns.
C) the evolutionary history of female mate choice.
D) how behavior is shaped by the environment an animal inhabits early in life.
E) the relative effects of male-male competition and female mate choice in the process of sexual selection.

Question 7

Which of the following statements regarding runaway sexual selection models is FALSE?

A) Two genes exist-one gene that codes for the male trait, and one gene that codes for the female preference-but only one gene is expressed in each sex.
B) Runaway selection can promote increasingly exaggerated male traits and female preferences.
C) Genetic linkage of the alleles codes for the male trait and the female preference.
D) Two genetically derived traits cannot coevolve.
E) Positive correlation exists between the strength of the female preference and the male phenotype.

Question 8

The "Hamilton-Zuk" parasite resistance hypothesis falls under which category of sexual selection models?

A) good genes
B) direct benefits
C) sensory exploitation
D) runaway selection
E) none of the above

Question 9

Which of the following statements does NOT apply to Höglund and colleagues' studies on mate-choice copying in black grouse?

A) Females synchronize their trips to male territories.
B) Stuffed "dummy" females were constructed to assess whether females prefer males that had mated previously.
C) Their studies suggest that younger, inexperienced females show a greater propensity to copy than older, experienced females.
D) A single male grouse monopolizes mating opportunity on the lek.
E) Females copy choices of other females only when the courting male is of superior quality.

Question 10

Fluctuating asymmetry refers to:

A) asymmetrical traits that confer a fitness advantage in the form of increased reproductive success.
B) deviations from perfect symmetry that fluctuates from the right to the left sides of the body throughout an organism's lifetime.
C) random deviations from perfect symmetry of the body on its right and left sides of the body.
D) any trait that indicates the overall health of an individual.
E) deviations from perfect symmetry that result from an extremely stable environment during development.

Question 11

Apart from differential investment in gametes, what other factors might be involved in females being the choosier of the two sexes? Under what circumstances should males be choosy as well?

Question 12

Describe at least three major components to the runaway sexual selection hypothesis. Also, contrast how runaway sexual selection might work when female preferences are determined genetically versus culturally.

Question 13

Obtain a copy of the review by Birkhead and Pizzari (2002) titled "Postcopulatory Sexual Selection" (Nature Reviews Genetics, vol. 3, p. 262-273). Drawing on the concepts outlined in this paper, discuss how both male-male competition and female choice could be involved in the process of sexual selection after insemination has occurred.

Question 14

You are interested in exploring the evolution of mate choice copying and, as a start, you have examined the presence/absence of mate choice copying in males and females of 30 closely related species of fish (e.g., members of the same family). You find considerable variation among species in terms of whether or not they copy and which sex (if either) copies. Now, you would like to understand whether aspects of the fishes' habitats, mating systems, and patterns of parental care and other forms of reproductive investment might explain some of this variation. Read the papers by Vakirtzis (2011), "Mate Choice Copying and Nonindependent Mate Choice: A Critical Review" (Annales Zoologici Fennici, vol. 48, pp. 91-107); and by Frommen and colleagues (2009), "Mate-Choice Copying When Both Sexes Face High Costs of Reproduction" (Evolutionary Ecology, vol. 23, pp. 435-446).
Using the content of these papers as a springboard, develop at least three hypotheses regarding conditions that might be most favorable for the evolution of mate choice copying in males, females, or both sexes. Now, based on what you learned in Chapter 2, develop a strategy for investigating the evolution of mate choice copying in your study organisms using phylogenetic methods.

Question 15

Imagine a situation where some males in a population mimic the behavior of females. For instance, in tiger salamanders, some males (M1) will mimic the "tail-nudging" behavior of a female and cause an unsuspecting male (M2) to deposit a spermatophore, i.e., a packet of sperm. M1 then deposits his own spermatophore on top of that of M2. Thus, a female will pick up the sperm of the mimic instead of the sperm from the original courting male. How would you classify this type of behavior-as intrasexual or intersexual selection? Why?

Question 16

Read the paper by Akre and colleagues (2011), "Signal Perception in Frogs and Bats and the Evolution of Mating Signals" (Science, vol. 333, pp. 751- 752). Describe how female túngara frogs and frog-eating bats apply opposing selection pressures on the evolution of male túngara frog calls. Then, describe how the authors applied Weber's Law to understand potential limits on the evolution of increasingly exaggerated male calls.