1. Animal Reproduction
Chapter 46

2. Two Ways to do it… Asexual Reproduction Sexual Reproduction
Creation of offspring without the fusion of egg and sperm
Sexual Reproduction
creation of an offspring by fusion of a male gamete (sperm) and female gamete (egg) to form a zygote

3. 4 Types of Asexual Reproduction
1. Fission
separation of a parent into 2 or more individuals of about the same size
Common in invertebrates
2. Budding
new individuals arise from outgrowths of existing ones

4. What type of reproduction? What type of reproduction?
Figure 46.2 Asexual reproduction of a sea anemone (Anthopleura elegantissima)

5. 4 Types of Asexual Reproduction (page 2)
3. Fragmentation
breaking of the body into pieces, some or all of which develop into adults
Fragmentation must be accompanied by regeneration, regrowth of lost body parts

6. 4 Types of Asexual Reproduction (page 3)
4. Parthenogenesis
It gets weird here, so stay with me
the development of a new individual from an unfertilized egg
There is a female (egg producer) & there is a male, but no fertilized egg
The egg doubles its chromosomes during parthenogenesis = diploid (viable) organism

7. Why sex? Seriously? Humans & dolphins know why  Genetic recombination
Accelerate adaptation to environmental forces
Shed harmful genes more rapidly

8. Asexual reproduction Sexual reproduction Female Female Male
Generation 1
Female
Generation 2
Male
Generation 3
Generation 4

9. Patterns of Reproduction
1. Ovulation
Release of mature eggs
Typically cyclical in nature
Influenced or determined by hormonal cycles
Associated with the release of chemicals (pheromones) indicating sexual receptivity (estrous cycle)
Also influenced by environmental cues, e.g. day length, changing of seasons, etc.

10. Patterns of Reproduction (page 2)
2. Hermaphroditism
each individual has male and female reproductive systems
Individuals can self-fertilize or mate
Some individuals are capable or switching genders depending on environmental conditions
Effective reproductive strategy for solitary animals

11. Patterns of Reproduction (page 3)
Who’s your daddy?
3. Sex Reversal
Individuals can change gender during its lifetime
Bluehead wrasse
Reef fish
If male dies, largest female becomes a male
She (He) produces sperm now

12. Fertilization Fertilization - union of sperm & egg
2 Types of Fertilization
External Fertilization
Eggs shed by the female are fertilized by sperm in the external environment
Large number of gamete production
Internal Fertilization
Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract
Adaptation to dry environments

15. Female Reproductive Physiology
Female gonads (ovaries) lie inside the abdominal body cavity
Each ovary contains many follicles, which consist of a partially developed egg, called an oocyte, surrounded by support cells
Prior to birth each oocyte is arrested in Prophase I (meiosis I)
Called primary oocyte

16. Puberty The primary oocyte stays in prophase I until puberty
Beginning at puberty, 1 oocyte per cycle completes meiosis I & arrests at metaphase II
Called secondary oocyte after metaphase II
Due to FSH secretion, a follicle grows and an egg or oocyte continues its development
Finally, following fertilization oocyte completes meiosis II

20. Spermatogenesis differs from oogenesis in which ways?

21. Differences Spermatogenesis Oogenesis Production 4 spermatids 1 egg
Duration
Continuous from puberty to death
Discontinuous
Begins before birth
Stops
Starts up after puberty
Menopause
Meiosis
Continuous process, and completes at regular intervals
1. Eggs are arrested in Prophase I, prior to birth
2. Prophase I  Metaphase II,
3. Finish after fertilization

22. Female Cycles Primates have menstruation cycles
Endometrial lining is shed from the uterus through the cervix & vagina
3 Phases of Menstrual Cycle
1. Menstrual Flow Phase
Most of the endometrium is shed, menstrual bleeding occurs
2. Proliferative Phase
Endometrium begins to regenerate & thicken
3. Secretory Phase
Endometrium continues to thicken and if no embryo is implanted, proceeds to menstrual flow phase

24. Ovarian Cycle Controlled by hormones Parallels the menstrual cycle
Note the important role of hormones throughout the cycle
Note the parallels between the ovarian & menstrual cycle as well

25. GnRH –
Gonadotropic releasing hormone
Note: FSH stays relatively constant
LH shoots up = ovulation

26. Estradiol – secreted by ovarian follicle
-- Causes endometrial lining to thicken
Progesterone – follicle rupturing causes spike in this hormone
-- When it falls, so too the endometrial thickening