W3: Mating Systems

Question 1

Monogamy

Answer 1

(one marriage) both sexes have 1 mate.

Lifelong & serial

Question 2

Polygamy

Answer 2

(multiple marriages) one or both sexes have more than one mate

Question 3

Polygyny

Answer 3

(multiple females) some males have more than one mate; females have just one.

Question 4

Polyandry

Answer 4

(multiple males) some females have more than one mate; males just have one

Question 5

Promiscuity & Polygynandry

Answer 5

both males and females can have more than one mate

Question 6

What type of mating is costly at the species level?

Answer 6

Multiple matings are costly at the species level.

Question 7

Genetic benefits of polyandry

Answer 7

1. Fertility insurance
2. Good genes
3. Genetic compatibility
   Material Benefits:
4. More resources
5. Better protection
6. Infanticide reduction

Question 8

Fertility Insurance Hypothesis

Answer 8

Mating with several males reduces the risk that some of the female’s eggs will remain unfertilized dues to mating with a partially or completely infertile male.

Question 9

Good Genes Hypothesis

Answer 9

Females mate with more than one male because their social partner is of lower genetic quality than other potential sperm donors whose genes will improve offspring viability or sexual attractiveness.

Question 10

Genetic Compatibility Hypothesis

Answer 10

Mating with several males increases the genetic variety of the sperm available to the females, increasing the chance that some will be genetically compatible with her eggs.

Question 11

More Resources Hypothesis

Answer 11

More mates mean more resources or parental care received from the sexual partners of a female.

Question 12

Better Protection Hypothesis

Answer 12

More mates mean more time with protectors who will keep other males from sexually harassing a female.

Question 13

Infanticide Reduction Hypothesis

Answer 13

More mates mean greater confusion about paternity of a female’s offspring and thus less likelihood of losing offspring to insecticidal males.

Question 14

How do Gunnison’s prairie dogs increase their probability of giving birth and increasing litter size?

Answer 14

By having multiple sexual partners

Question 15

The Monogamy Paradox

Answer 15

Why would any male restrict his efforts to fertilizing just one female?

Question 16

Answer to the Monogamy Paradox:

Answer 16

1. Mate guarding: females are hard to find
2. Mate assistance: extra offspring outweighs cost
3. Female-enforced: females refuse to mate with already-mated male or chase off other females

Question 17

What is the associated mating system in an environment where males are unable to defend more than one female?

Answer 17

Monogamy or promiscuity

Question 18

What is the associated mating system in an environment where some males can defend more than one female?

Answer 18

Polygyny

Question 19

How did scientists study female & male dispersion in grey-sided voles?

Answer 19

• grey-sided vole females clump around concentrated food resources
• females experimentally moved around led to males clumped when females clumped, males dispersed when females dispersed.
• males experimentally moved around resulted in no change in female dispersion

Question 20

Polygyny Threshold Model

Answer 20

Fitness of second female sharing a male on high quality territory is equal to the fitness of female who nest monogamously on low quality territory.

Question 21

What are some male mating strategies?

Answer 21

1. Female defense
2. Resource defense
3. Scramble competition
4. Lekking

Question 22

Scramble Competition

Answer 22

Males don’t attempt to defend territories, rather they search for receptive females and try to mate with whomever then encounter.

Question 23

Lekking

Answer 23

Defense of a traditional display site that females visit to select a mate from among the several to many males displaying on the small, resource-free territory.

Question 24

Why do males cluster at leks?

Answer 24

1. Hot spot: males cluster when encounter rates are high
2. Hot spot: clusters form around attractive males
3. Predator Dilution:males cluster for safety
4. Female Benefit: females prefer to mate at particular sites or with males in clusters either for their personal safety or to compare males.