1. Reproduction in Animals
• Important to survival of a species
• Two Types:
– Asexual – one parent; offspring are clones
• Bacteria, plants, amoebas, and simple
organisms
– Sexual – joining of gametes (egg + sperm);
increases genetic variation
• Some plants, many animals

2. Asexual vs. Sexual Reproduction
ASEXUAL SEXUAL
One parent Two parents
Offspring are clones of parent Egg + Sperm = Offspring
Offspring/cell’s DNA same as Offspring DNA different from
parent parents and each other
Same parental genes passed
New combinations of genes
down
Less/no genetic diversity Increase in genetic diversity
Could be disadvantage if Offspring/species better able to
environment changes evolve and adapt to changing
environment
Egg/Sperm produced by Meiosis

3. Examples of Asexual Reproduction
regeneration
parthenogenesis
vegetative
budding
fission

4. Fertilization and Development
• Fertilization – joining of egg and sperm
Internal vs. External
• Development – differentiation and
maturation of fertilized egg
Internal vs. External

5. Fertilization and Development in Animals
Fertilization Requirements Advantages Disadvantage Examples
s
External - Large # of Parents don’t
Less chance
Frogs, coral,
- gametes join gametes need to be in sponges,
outside of body - Water
of fertilization
the same many fish
place
- Specialized - chance of
Internal fertilization
Parents must Birds, reptiles,
- gametes join organs be close mammals,
- Mating rituals - Lower # of
inside of body together some fish
gametes
Development Requirements Advantages Disadvantage Examples
s
External No parental
Low chance
Frogs, many
- growth outside Water or Shell care needed fish, reptiles,
of survival
of parents’ body birds
Specialized chance of
Internal organs support offspring Pregnancy is Mammals,
- growth inside survival demanding some sharks &
of parent’s body developing snakes
egg

6. Reproductive Adaptations in Animals
Amplexus in Frogs Eggs prevent reptiles
from drying out on land
Specialized
organs in
damselflies

7. The Amniotic Egg
• Evolutionary
adaptation that
allowed fertilized
eggs to develop on
dry land
• Shell and
membranes protect
embryo
• Produced by
reptiles, birds, and
some mammals