MATING SYSTEMS AND REPRODUCTION

Question 1

a) What is monogamy?

b) What are the different forms of polygamy?

Answer 1

a) pair matings

b) - polyandrous, where female mates with many males
- polygynous, where male mates with many females
- promiscuity, both sexes have multiple partners

Question 2

What drives reproductive conflict?

Answer 2

ANISOGAMY

Question 3

How has monogamy evolved in some species?

Answer 3

• male parental care is indispensable
• males are forced away from future mates due to aggression from already mated females
• an unmated male may be more advantageous
• males may prove successful by defending exclusive access to female
• males are less successful with 2 females than one

Question 4

3 hypotheses for monogamy evolution

Answer 4

• mate assistance hypothesis
• mate guarding hypothesis
• female enforced monogamy

Question 5

Distinguish between obligate and facultative monogamy

Answer 5

OBLIGATE - both parents required for offspring survival

FACULTATIVE - density of food and mates v low

Question 6

a) Pure polyandry is vanishingly (a)

b) Whereas, polygyny is very (b)
2 forms?

c) How does polygyny play out when there are widely dispersed females and resources?

Answer 6

a) rare

b) popular
- female defence monogamy, one male defends a group of females
- resource defence monogamy, one male defends a resource that females require

c) lekking
OR scramble competition monogamy

Question 7

Why would females be promiscuous?

Answer 7

• avoid male harassment
• dubiously, males provide support for young
• offsets risk of male infertility
• sperm competition
• increase genetic diversity
• cryptic female choice through sperm competition

Question 8

In monogamy, there is (a) sexual selection. In polygyny there is loads of sexual selection, leading to sexual (b).

Answer 8

a) little

b) dimorphism

Question 9

3 factors leading to sociality

Answer 9

• large brain
• endotherm
• strong mother offspring bond

Question 10

2 ways in which lactation is performed

Answer 10

1) aereolar patches are milk glands open to surface

- nipples or teats

Question 11

Where did mammary glands develop from?

Answer 11

• from apocrine and sebaceous glands

Question 12

Why lactate?

Answer 12

• allows rapid growth of tiny young
• may buffer young against food shortage
• transfer of maternal immunity, hormones, antioxidants,
• limits lack of paternal care

Question 13

What does oriparous mean?

Answer 13

egg laying

Question 14

What is the function of placenta?

Answer 14

to nourish embryo whilst inside uterus

Question 15

In some mammals with no placenta, there is no direct link between the embryo and the mother, all they have is ___.

Answer 15

endometrium

Question 16

Distinguish between a chorioallantoic placenta and a choriovitelline placenta

Answer 16

chorioallantoic - formed from chorion and allantois fused

choiovitelline formed from yolk sac or vitelline membrane

Question 17

What do all therians begin with? (placenta)

Answer 17

a chorioallantoic placenta

Question 18

How do eggs develop in prototherian early amniotes?

Answer 18

1) ovum released from ovary
2) fertilised prior to entering oviduct
3) mucoid coat secreted around egg
4) basal shell layer secreted around egg
5) second layer added
6) embryo develops
7) uterine section nourishes embryo
8) 3rd shell layer added and it is laid

Question 19

What has changed between prototherian reproduction and metatherian reproduction?

Answer 19

1) separate rectum from urogenital sinus
2) paired lateral vaginae for sperm passage
3) midline pseudovaginal canal for birth of young

Question 20

How are metatharians born?

Answer 20

• they are born severely underdeveloped and have to climb in to a pouch to suckle

Question 21

How does milk composition vary?

Answer 21

Begins high in protein and low in fat then switches to low in protein high in fat

Question 22

What characteristics are changed in the transition from metatheria to eutheria?

b) how about egg development?

Answer 22

1) further separation of rectum and urogenital sinus
2) single middle vagina
3) have divided uterus

b) begins as chorovitelline placenta and becomes chorioallantoic

Question 23

Different degrees of integration between mother and foetus?

Answer 23

1) EIPTHELIO
- all 6 layers present

2) syndesmo
uterine epithelium lost

3) endothelio
- embyro in contact with maternal capillaries

4) hemo
- chorion in direct contact with maternal blood

5) homoendo
- fetal capillaries in direct contact with maternal blood

Question 24

Final key eutherian distinctive characteristics

Answer 24

• long gestation period

- shorter relative lactation period