Reproductive Strategies in Mammals

Types of Reproduction, Mating System, Monogamy, Polygamy
Mode of Reproduction in Monotremes, Marsupials and Placental mammals, Courtship Behavior.

1. Reproductive Strategies in
Mammals

2. Reproductive Strategies in
Mammals

3. Content
•Types of Reproduction
•Mating System
•Monogamy
•Polygamy
•Mode of Reproduction in Monotremes, Marsupials and
Placental mammals
•Courtship Behavior.

5. 3 Kinds of mating system-
•1-Monogamy
•2-Polygamy
•3-Promiscuity
Monogamy
•Monogamy is a kind of mating system in which individual pair for a long period of time or says
permanently.
Polygamy
•Polygamy is a kind of matting system in which individuals of either sexes mate with more than
one individual.
It is of two types as-
•1-Polyandry-when one female mate with more than one male. It is very rare in nature. Only
reported in African wild dog.
•2-Polygyny-when one male mate with several female. e.g. horses, wild asses deer species etc.
Promiscuity
•It is kind of matting system in which there is no limiting boundaries of pairing of either sexes.
E.g. Elephant, Giraffe, tree shrews etc.
It is also of two types as-
•1-Successive-It is the one in which one individual of either sex mates with individuals of other
sexes in successive manner.
•2-Simultaneously-It is the one in which individuals of either sexes mates with the opposite
sexes simultaneously.

6. Monogamy

8. Polygyny and Polyandry

9. The 3 subclasses of
mammals differ
strikingly in their
modes of reproduction
Prototheria (monotremes) Metatheria (marsupials)
Eutheria (placentals)

10. Monotremes –
1)Lay eggs
2)Cloaca
3)No nipples

12. Monotremes

13. Some features of monotreme
reproduction
•Ovaries larger (relative to
body size) than other
mammals
•Oviducts open into
common urogenital sinus,
similar to reptile cloaca
(meaning of name
“monotreme”)
•Milk secreted by glands in
skin, licked from tufts of
fur at concentrations of
glands
•Testes abdominal, penis is
sac in floor of cloaca
•Young have “egg tooth”
like birds to help break
out of egg
•Platypus: 1-2 eggs
•Echidna: 1 egg

14. •Egg-laying mammals , they lay heavily yolkedeggs.
•The egg is retained for some time within the mother,
who actively provides the egg with nutrients.
•Endothermic
•Lacks pinna (has only ear slits)
•3 bones in middle ear
•Brain lacks corpus callusom

15. •They have no nipples, a milky fluid oozes out
from modifies sweat glands onto tufts of hairs
in shallow pits of the abdomen, from which
the young lick it up.
•The monotremeleg bears a spur in the ankle
region, the spur is non-functional in echidnas,
but contains a powerful venom in the male
Platypus.

16. •Non-placentalmammals
–Yolk sac serves as placenta
–give birth to premature young climbs from the mother's birth canal to
the nipples. it grabs onwith its mouth and continues to develop
–Some marsupials have a rudimentary placenta that functions for only a
short time, such as the bandicoot
Marsupial

17. •females typically have an external pouch –“marsupium” in which the
immature young are raised after birth until early infancy
•Short gestation timesis due to having a yolk-type placenta in the mother
marsupial (8-43 days)
Young Ones

18. The opossum
1)Young tiny at birth (0.16 g)
2)Attach to nipples in pouch
(marsupium)
3)Short gestation, longer
lactation

19. Some differences (from placentals) found in
marsupials
•Eggs slightly larger than in
placentals(0.12-0.28 mm vs
0.07-0.15 mm)
•Uteri separate, but females
also have paired (not single)
vaginae
•Young never larger than
about 1 g, no matter size of
mother
•Gestation always short as or
shorter than length of estrus
cycle
•No invasive placenta
•Many have pouch, but
some only have folds of
skin, and a few don’t have
anything
•In males, penis is bifid
(forked) like female
vaginae
•Scrotum lies in front of
penis, opposite pattern in
placentals

20. Differences in female reproductive tracts

21. O = ovulation
F = fertilization
B = formation of blastocyst
I = implantation of
blastocyst in uterine wall
DP = development of
placenta
DF = development of fetus
Part = parturition (birth)
General pattern for a placental mammalian
reproductive event is:
O -> F -> B -> I -> DP -> DF -> Part
Timing is important!
Births should occur so that
lactation, the most
energetically demanding
period, coincides with the
most favorable
environmental conditions in
a seasonal environment

22. Reproductive Strategies in (Eutherians)
Primates
Placental: thedevelopmentoccursinsidetheuterus. Themother
has a connectionwiththebabythroughtheplacenta.

23. Primates

24. Carnivores

25. Deers

26. Bovids

27. Hum Do HumareDo