1. CHAPTER 27 Reproduction and Embryonic Development
Module 27.1

2. Mating Without Males
There are no male desert-grassland whiptail lizards
The species reproduces without copulation or fertilization

3. This photo shows a ritual behavior that primes a female to lay eggs
The female on top behaves much like a male in other species of whiptail lizards
Mating behavior seems to be an evolutionary leftover

4. Reptiles, birds, and mammals have four embryonic membranes
Although the reproduction method of desert-grassland whiptails is unusual, their embryonic development is similar to all other animal species
Reptiles, birds, and mammals have four embryonic membranes
Chorion
Embryo
Amnion
Allantois
Yolk
Yolk sac
Shell

5. All animal species have three stages of embryonic development
Mitotic cell division
Cellular differentiation
Formation of the body and its structures

6. 27.1 Sexual and asexual reproduction are both common among animals
ASEXUAL AND SEXUAL REPRODUCTION
27.1 Sexual and asexual reproduction are both common among animals
Asexual reproduction
Budding
Fission
Fragmentation, accompanied by regeneration
Development of an unfertilized egg
Figure 27.1A

7. Sexual reproduction
The fission of two haploid gametes from two parents to form a diploid zygote
Figure 27.1D

8. Rotifers can reproduce both asexually and sexually
“Head”
Intestine
Ovary
Eggs
Hermaphroditism
A single individual has both male and female reproductive systems
Figure 27.1B, C

9. Advantages of asexual reproduction
A single individual reproduces
Many offspring are produced rapidly
Disadvantage of asexual reproduction
Little or no genetic variation

10. Advantages of sexual reproduction
Increases genetic variation
Enhances reproductive success in changing environments
Disadvantage of sexual reproduction
Locating a mate