Mating Systems

Question 1

What is Bateman’s principle

Answer 1

“the theory that females almost always invest more energy into producing offspring than males, and therefore in most species females are a limited resource over which the other sex will compete”

Question 2

How do males and females differ in time/ energy investments in offspring

Answer 2

• Males – invest time and energy in male competitions – gives them maximum number of mating
• Females – invest time/ energy to gain mate and parental care – maximises number of offspring

Question 3

What does Bateman’s principle suggest about sexual selection in males and females

Answer 3

Males optimise offspring QUANTITY

Females optimise offspring QUALITY (of sperm = quality of genetics)

Question 4

What 3 things are considered by a female choosing a mate?

Answer 4

Pheromones
Courtship rituals
Phenotypes (=good genes)

Question 5

What are the 3 types of Polygamy

Answer 5

Polygyny
Polyandry
Polygynandry

Question 6

Define Polygyny

Answer 6

1 males mates with lots of females

Question 7

Define Polyandry

Answer 7

1 females mates with lots of males

Question 8

Define Polygynandry

Answer 8

Everyone mates with everyone

Question 9

Name a species that is Polyandry

Answer 9

Anglerfish

Question 10

Name a species that is Polygyny

Answer 10

Elephant seal 
Spotted hyena
Gorillas
Hamadyras baboon 
Pheasants
Red Deer
Lions
Bengal Tiger

Question 11

What is Monogamy

Answer 11

One mate for a mating season or lifetime

Question 12

What animal group is monogamy most common in

Answer 12

birds/ aves

Question 13

What does DNA analysis show about monogamous bird species

Answer 13

Promiscuity occurs.

The offspring aren’t always genetically fathered by the resident male

Question 14

What percentage of mammal species are monogamous?

Answer 14

3%

Question 15

What percentage of Avian species are monogamous?

Answer 15

90%

Question 16

What percentage of monogamous birds’ offspring are actually fathered by another male

Answer 16

30%

Question 17

What does Bateman’s Principle suggest about monogamy?

Answer 17

Monogamy isn’t very/ at all beneficial to males (doesn’t select for quantity)

Question 18

What are 3 hypotheses for male monogamy

Answer 18

Mate-Guarding Hypothesis
Mate-Assistance Hypothesis
Female-Enforcement Hypothesis

Question 19

How does the Mate-Guarding Hypothesis explain male monogamy?

Answer 19

Males that stay with female, prevent other males mating with her.

Question 20

When is the mate-guarding hypothesis most beneficial?

Answer 20

When mates are hard to find

Or when the male becomes sterile after copulation

Question 21

Give an example of male suicide

Answer 21

Redback Spiders

Become sterile after copulation so place self in female’s jaws

Question 22

Why do Redback Spider males commit male suicide?

Answer 22

• Large male: female ratio = females are hard to find

- Males become sterile after copulation

Question 23

When is male sacrifice favoured?

Answer 23

• When less than 20% of males find a female

- When the male becomes sterile after copulation

Question 24

What is the male-assistance hypothesis?

Answer 24

Suggests males stay with partner because male assistance increase offspring survival and therefore lifetime reproductive output (Increased survival of young outweighs young gained from seeking extra mates)

Question 25

Give an example of animals that support the male-assistance hypothesis

Answer 25

``` Swans Emperor Penguins Seahorses Primates Rodents ```

Question 26

How does parental care work in seashorses?

Answer 26

Males carry eggs in brood pouch They synchronise reproductive cycle with females Both avoid extra pair copulations

Question 27

Explain the female-enforcement hypothesis for monogamy

Answer 27

- Female ensures the male does not have offspring that might compete with her own - She actively interferes with the male’s signally to attract other mates – usually some form of aggression

Question 28

Give an animal that supports the female-enforcement hypothesis

Answer 28

``` Razorbills Burying Beetles (Necrophorus) ```

Question 29

How do burying beetles support the female-enforcement hypothesis?

Answer 29

- After setting up one nest with a female, a male will want to attract another female (beneficial for HIM) - Male may add additionally females to the nest (releasing pheromones) - First female will attack the male if she detects these pheromones

Question 30

How do Djungarian Hamsters support the male-assistance hypothesis?

Answer 30

- Males help infants being born - No significant association between monogamy and male care - Males don't leave because if they are out looking for a female, they leave themselves open to cuckoldry

Question 31

How do songbirds support the male-assistance hypothesis?

Answer 31

- Both males and females can produce milk - Provide more food - Increases breeding success when food is scarce

Question 32

What happened to Male Spotless Starling behaviour when testosterone levels were reduced?

Answer 32

Testosterone levels reduced, they provided more food for broods and had higher fledgling rates per brood

Question 33

What happened to Male Spotless Starling behaviour when testosterone levels were increased?

Answer 33

Less food was provided to the brood | Ended up with lowest fledgling rate

Question 34

How does male presence in snow buntings (birds) affect young?

Answer 34

When male snow buntings were removed, females reared fewer than 3 young When males helped, 4x more young were reared

Question 35

How does hatching rates differ in biparental and uniparental starlings?

Answer 35

``` Biparental = 97% eggs hatched Uniparental = 75% eggs hatched ```

Question 36

How do Tree Swallows support the male-assistance hypothesis?

Answer 36

Polygynous Tree Swallow males fathered 0.8 fledglings Monogamous Tree Swallow males fathered 3.0 fledglings (over 3x more)

Question 37

How do Horned Beetles demonstrate alternative mating strategies?

Answer 37

- Nutrition affects body size - More nutrients = bigger horns in males - Long horns = mate-guarding behaviour - Small/ no horns = adopt sneaking strategy (dig tunnel to intercept female tunnel without begin noticed) Both strategies = effective

Question 38

How to Red Paper Wasps demonstrate alternative mating strategies?

Answer 38

- Smaller wasps = Patrollers - Larger wasps = Territorial (will chase away intruders) - Owning territory leads to greater number of mating opportunities - Territorial males rub abdomens across territory to apply pheromones, attracting females - Patrollers are too small to compete, so resort to sneaking behaviours – will sneakily mate with females in other territories when territorial male is temporarily away or distracted

Question 39

What are secondary sexual characteristics?

Answer 39

any physical characteristic developing at puberty which distinguishes between the sexes but is not directly involved in reproduction