Mammals 2

Question 1

Describe reproduction in monotremes.

Answer 1

• Primitive amniote condition with 1 or 2 eggs laid
• Eggs fertilised in Fallopian tube
• mineralised shell is applied and eggs are laid and incubated by female
• young born very immature.

Question 2

Describe reproduction in marsupials.

Answer 2

• Yolk sac placenta
• eggs fertilised in Fallopian tube
• females have two vaginas and a their medial birth canal forms between
• birth canal may or may not re-separate afterwards
• testicles sit on top of penis
• many species have divided penis.

Question 3

Describe reproduction in eutherians.

Answer 3

• foetus attaches to placenta via an ublilicus
• longer gestation time than monotremes and marsupials but can produce offspring at later age
• placenta transports nutrients from maternal circulation.

Question 4

How does a larger body size affect fertility in mammals?

Answer 4

Lowers fertility.

Question 5

Give the common factors of reproduction of various mammal types.

Answer 5

• internal fertilisation
• young fed with milk from mammary glands
• most young born helpless and rely on parental care.

Question 6

What factors may regulate the timing of births?

Answer 6

• Day length
• Hormones
• Delayed fertilisation
• Delayed implantation
• Slow development after implantation.