Mating Systems

Question 1

What is monogamy?

Answer 1

• A bond between a single male & single female
• Can last for part or whole of breeding season or for a lifetime

Question 2

What is polygamy?

Answer 2

• Individual has more than 1 mate in a breeding season or lifetime

Question 3

What is polygyny?

Answer 3

1 male, many females

Question 4

What is polyandry?

Answer 4

1 female, many males

Question 5

What is promiscuity?

Answer 5

Both males & females may mate with different individuals- have no outside relationship

Question 6

When is monogamy favoured?

Answer 6

• When males have little opportunity to monopolise multiple females as they are widely dispersed
• When sex ratios are biased in favour of 1 sex (females hard to locate or receptive for brief periods, promotes mate guarding)

Question 7

What is the disadvantage with mate guarding?

Answer 7

A female left by one male would potentially rapidly acquire another partner whose sperm would them fertilise her eggs

Therefore Venetian for a male to remain with his partner if receptive females are scarce

Question 8

How is fitness in monogamy maximised?

Answer 8

Shared parental care

Of either parents deserts, increased risk of mortality (wouldn’t pass genes to next generation)= “mate assistance hypothesis”

Question 9

What does monogamy assume?

Answer 9

Assumes mating only between the pair and that offspring are the progeny if the pair exclusively

In reality, they’re not always as monogamous as we think

Question 10

Monogamous Examples

Answer 10

Red backed salamander- females are aggressive towards partners who stray and have pheromones from other females on them

Shingleback (lizard). Mostly monogamous and keep same partner up to 10yrs. Pairs ones mate earlier then unpaired= advantage.

Question 11

What are the different types of polygyny?

Answer 11

• Female/harem defence polygyny
• Resource defence polygyny
• Scramble competition polygyny
• Lek polygyny

Question 12

What is female/harem defence?

Answer 12

Males control access to females directly (due to female gregariousness)

Question 13

What is resource defence polygyny?

Answer 13

Males control access to females indirectly by monopolising critical resources

(E.g- females in breeding condition they need access to resource must mate with them to gain access)
Male elephant seals, ‘beach master’

Question 14

What affects the ability of males to monopolise resources?

Answer 14

The spatial distribution

Question 15

What is the polygyny threshold model?

Answer 15

Predicts the female should accept the role of the 2nd mate when there are superior resources as opposed to being monogamous on a poor quality area.

Question 16

Example of polygyny threshold model!

Answer 16

Female red winged blackbirds

• polygynous mating decreases reproductive success
• nesting over water increases reproductive success

Question 17

What is the advantages/disadvantages of polygynous relationship in birds?

Answer 17

The females have a lower fledging success rate when shared with another female.

However males will have the success of both the ‘mistress’ and main partner combined

Question 18

What is Scramble polygyny?

Answer 18

When receptive females are widely dispersed, males better off not being territorial but to just try their hardest to find a female.

Males success entirely dependant on ability to move around and compete for female

Question 19

Example of scramble polygyny?

Answer 19

Female 13-lined ground squirrels live in fairly spaced out groups: males male rounds visiting burrow sites.

Involves direct male-male/sperm competition

Makes can smell via urine or hormones if female is coming into season (may visit this individual more often)

Question 20

What is explosive breeding assemblage?

Answer 20

Females become receptive for only a brief time and congregate at a breeding site

Males gather there too and compete for females (frogs)

Question 21

What is lek polygyny?

Answer 21

Males congregate at predictable location in lekking species

Males display for females and they choose males on appearance and displays (sexual selection)

Males provide no resources including parental care

Question 22

Example of lek species?

Answer 22

Lechwe
Kob
Topi (antelope(

Leks form because males can’t monopolise females

Question 23

What are the hypotheses for evolution of lekking?

Answer 23

• Hot Spots
• Hot Shots
• Female Preference

Question 24

What is the hot spots hypothesis?

Answer 24

Males gather at sites where they are likely to encounter females

Question 25

What is the hot shots hypothesis?

Answer 25

Subordinate makes cluster around most attractive males in order to be seen

Question 26

What is the female preference hypothesis?

Answer 26

Females prefer to choose from groups of males because comparisons are easier to make

Question 27

What is different in polyandry compared to the others?

Answer 27

Sexual dimorphism is reversed.
Females are the ones with attractive characteristics and who will fight amongst each other for males

Question 28

What are the types of polyandry?

Answer 28

• sequential, female mates with male, lays eggs and leaves male to incubate them while she goes to mate with others
• simultaneous, each female holds large territory containing nesting territories of 2 or more males who care for eggs and young

Question 29

Where might promiscuity occur?

Answer 29

Where environment is completely unpredictable or where encounters between sexes are rare

E.g- chimps, kangaroos, some whales and dolphins, rabbits

Question 30

What is hierarchical promiscuity?

Answer 30

Females mate with any male but dominant male will get to mate with receptive females and subordinate males may have few mating opportunities

Question 31

What are the factors favouring monogamy?

Answer 31

• spatial and temporal distribution of females
• need for male parental care
• need to ensure paternity (mate guarding)

Question 32

What are the factors favouring polygyny?

Answer 32

• female behaviour that allows male defence of several females
• female dependence on a controllable resource

Question 33

What are the factors favouring promiscuity?

Answer 33

• unpredictable environment
• encounters between sexes are rare

Question 34

In which group of animals is monogamy most common and in which group is is rarest?

Answer 34

Common- birds
Rarest- mammals

Question 35

Give 3 examples of polyandrous species.

Answer 35

Waders:
1. Spotted sandpiper
2. Red-necked phalarope
3. African jacana