Mating systems

Question 1

what are the 4 types of mating systems?

Answer 1

monogamy

polygamy:
- polygyny
- polyandry
- promiscuity

Question 2

define:
polygyny
polyandry
promiscuity

Answer 2

males mate with multiple females

females mate with multiple males

both sexes have multiple partners

Question 3

what are the features of monogamy?

Answer 3

male + female form pair bond

each male + female has 1 mate during a breeding season

sometimes have bi-parental care

Question 4

what are the different hypotheses for being monogamous?

Answer 4

mate-guarding hypothesis

mate-assistance hypothesis

Question 5

what is the mate-guarding hypothesis?

Answer 5

if the female remains receptive after the 1st mating

the male might stick with her and prevent her from mating with others

as low likelihood of finding a 2nd female

Question 6

what is the mate-assistance hypothesis?

Answer 6

protection
- males protect breeding territory

bi-parental care
- 2 parents provide better care than 1

Question 7

why would males protect females in the mate-assistance hypothesis if it increases their risk?

Answer 7

increases their risk of dying

BUT decreases inseminated female’s risk

female is carrying the male’s offspring
-> so would increase reproductive success

Question 8

describe an experiment which demonstrates monogamous parents compensating

Answer 8

put a weight on a bird
= additional effort when it collects food for young

if the female was weighted the male compensated and vice versa

NOT completely compensated so overall less results

Question 9

how do we know socially monogamous animals are NOT genetically monogamous?

Answer 9

extra-pair fertilisations and copulations are common

EPFs detected by DNA fingerprinting

Question 10

what are the benefits of being polyandrous?

Answer 10

EPFs can allow females to find males with better genes

genetic variety of offspring

reduce infanticide risk
- some chance the offspring are that male’s

reduce male harassment
- if female mates with a male, heel leave her alone

more resources

Question 11

what are the costs of polyandry?

Answer 11

STIs

predation while searching for mares

mating when could be getting food for young

Question 12

what are the features of polyandry?

Answer 12

male provides care for young

females are larger + more aggressive

can lead to infanticide by females

e.g. in shorebirds

Question 13

give an example of polyandry in mammals

Answer 13

Callitrichids

females always have twins which are large (25% of her weight at birth)

female mates with multiple males
-> their help is needed to carry the young

Question 14

what are the features of polygyny?

Answer 14

some males mate with many females
BUT other males remain unmated

females mate with single mate

females provide most or all care for young

male size»>female size

Question 15

what are the types of polygyny?

Answer 15

female defence

resource defnce

lek

Question 16

describe female defence polygyny

Answer 16

females aggregate in favourable breeding sites where males can monopolise several females
- male guards territory

Question 17

describe resource defence polygyny

Answer 17

1. males settle on breeding territoires (resource)
2. females choose a mate (i.e. territory)

some males are chosen by several females
-> the secondary/tertiary female pays a cost as the male only helps the primary female raise young

BUT better to have the good territory

Question 18

describe the features of leks

Answer 18

males display on very small territories that have no resources = lek

males provide no care for young

females visit many males but copulate with one

male mating success heavily skewed

Question 19

how are leks beneficial?

Answer 19

males

• if females are widely distributed
• > leks attract females

females
- reduced the cost of searching for a mate

Question 20

describe the mating system of Dunnocks

Answer 20

highly variable

monogamy, polygyny, polyandry + polygynandry can all occur in the same population

Question 21

when is RS highest for males and females in Dunnocks?

..so what is the observed mating system?

Answer 21

males
= polygyny

females
= polyandry

a compromise between the interests of males and females
-> outcome determined by resource distribution

Question 22

what is the female distribution theory of mating systems?

Answer 22

females are distributed according to resources

males distributed according to females

Question 23

give an example of why males might be parental

Answer 23

Stickleback

• males build nests that attract females to lay clutches
• > male protects eggs

male can guard 10 clutches until hatch
-> females can only lay 7 w/out care

Question 24

give an example of a brood parasite

why do they accept the eggs?

what is the risk to being a brood parasite?

Answer 24

Cuckoos lay eggs in reed warbler nests

if parent mistakenly removes own egg
-> maybe most costly than excepting cuckoo egg

host might not accept all/any eggs