Kingdom Animalia: Reproduction

1. Kingdom Animalia:Reproduction

2. Asexual Reproduction in animals Common in invertebrate animals Budding: offspring are outgrowths of parents Fragmentation: animal breaks into two or more parts each fragment can become a individual RESULT: offspring are identical to parent (no genetic variation)

3. Regeneration, the regrowth of lost body parts, normally follows _____. all types of asexual reproduction fission parthenogenesis fragmentation

4. Sexual Reproduction in animals Present in all groups of animals RESULT: offspring are a new combination of both parents

5. The "reproductive handicap" for sexual reproduction refers to _____. the difficulty of finding mates the need for maturation prior to reproduction dependence on hormonal cycles have only half the offspring are females the need to provide energy for the offspring

6. In an animal that switches between sexual and asexual reproduction, when is sexual reproduction more likely to occur? when conditions for survival are favorable when males and females find each other when conditions for survival are unfavorable What conditions favor sexual over asexual remains a complete mystery.

7. Fertilization depends on mechanisms that help sperm meet eggs of the same species Things to consider: Sperm must be able to find an egg Gametes need a moist environment (prevent drying out and help sperm swim)

8. Two approaches to fertilization: 1. External fertilization: release of gametes into the surrounding environment A moist habitat is always required for external fertilization to allow sperm to swim to the egg and to prevent the gametes from drying out In sessile animals vs mobile animals

9. Two approaches to fertilization: 2. Internal fertilization: Sperm is deposited in or near the female reproductive tract and fertilization occurs in it In sessile animals vs mobile animals Requirement: Find each other (using pheromones, sounds, light) cooperative behavior between male and female, (courtship behaviors, nuptial gifts) Advantages and disadvantages of each type of fertilization ? Requirement: cooperative behavior between male and female, (by using pheromones, courtship behaviors, nuptial gifts) Advantages and disadvantages of each type of fertilization ?

10. In close comparisons, external fertilization often yields more offspring than does internal fertilization. However, internal fertilization typically offers the advantage that _____. it requires expression of fewer genes and maximizes genetic stability it permits the most rapid population increase the smaller number of offspring produced often receive a greater amount of parental investment it requires less time and energy to be devoted to reproduction

11. Animals utilizing external fertilization are typically _____. land animals aquatic animals mammals insects animals that reproduce asexually

12. Reproductive patterns Animals may reproduce exclusively asexually or sexually, or they may alternate between the two modes Like Obelia Hermaphroditism : An animal that has both sexual organs Beneficial to animals that are sessile , burrowing or endoparastitic why? Sequential hermaphrodites In reef fish and oysters, changes its sex with age and size Wrasses: female first, male live in harems In clown fish male first

13. Reproductive patterns Parthenogenesis: development of an embryo from a unfertilized egg Beneficial when environment is stable In aphids, as a response to seasons or stress During environmentally stable times  eggs ___________ During environmental stress  eggs _____________ In bees, wasps and ants, role in social organization Fertilized eggs  queens and sterile workers Unfertilized eggs  males drones

14. Salamander and insect populations consisting only of genetically identical females lack males because _____. sperm do not fuse with eggs during reproduction, but the eggs develop into embryos anyway a mutation in the population has eliminated the salamander equivalent of the Y chromosome a sex-linked, dominant, lethal mutation is fixed in the population males are killed at birth by their mothers these ancient forms preceded sexual evolution

15. Reproductive patterns: type of birth Oviparous (egg-birth) embryos are laid outside of body for development (there is a yolk that feeds it) may show various degrees of parental care Ovoviviparous (egg-live-birth) embryos are retained inside but embryos derive all nourishment for yolk inside the egg common earthworms, insects, sharks and snails and in some reptiles Viviparous (live-birth) embryos develop inside deriving their nourishment directly from the mother (i.e. umbilical chord in mammals) mostly in lizards, snakes, mammals and sharks but also in scorpions