Reproductive modes

1
Reproductive modes in animals

• Reproductive modes

• Two general reproductive modes in animals

• Asexual

• Production of genetically identical daughter
  cells from a single parent (by mitosis)

• Daughter cells differentiate and develop into new
  individual

• Sexual

• Production of genetically unique gametes (by
  meiosis)

• isogamous , - mating types produce same-sized
  gametes

• anisogamous males and females produce
  different-sized gametes (egg and sperm)

• Zygote formed by union of two gametes (syngamy)

• Zygote undergoes mitosis and cells differentiate
  to develop into new individual

How are new organisms produced?
2
Reproductive modes in animals

• Reproductive modes

• Asexual reproduction

• Budding asexual reproduction in which outgrowth
  becomes a new

• Common in Phylum Cnidaria (e.g. Hydra)

How are new organisms produced?
3
Reproductive modes in animals

• Asexual reproduction

• Parthenogenesis development of an egg into new
  individual without fertilization

• Sonoran spotted whiptail lizard

• unisexual, all-female species that breeds by
  parthenogenesis

• ovulation stimulated by "pseudocourtship" among
  the females

• unfertilized eggs produce hatchlings genetically
  identical to mothers

How are new organisms produced?
4
Reproductive modes in animals

• Asexual reproduction

• Variations of parthenogenesis

• Honeybees

• Queen mates and stores sperm in spermatheca she
  controls use of sperm when producing offspring

• males (drones) develop from unfertilized eggs
  (parthenogenesis)

• females (workers) develop from fertilized eggs
  (sexual reproduction)

How are new organisms produced?
5
Reproductive modes in animals

• Asexual reproduction

• Variations of parthenogenesis

• Daphnia (Water fleas)

• Freshwater crustaceans (Phylum Arthropoda) that
  feed on algae

• Cyclical parthenogensis alternate between sexual
  reproduction (during periods of stress) and
  asexual reproduction

How are new organisms produced?
6
Reproductive modes in animals

• Reproductive modes in animals

• Variation of sexual reproduction

• Simultaneous hermaphroditism single individual
  has both male and female reproductive structures

• Tapeworms self-fertilization

• Earthworms during sexual reproduction each worm
  acts as male and female

How are new organisms produced?
7
Reproductive modes in animals

• Reproductive modes in animals

• Variation of sexual reproduction

• Sequential hermaphroditism single individual
  changes sex during lifetime

• Protogyny change from female to male

• Protoandry change from male to female

How are new organisms produced?
8
Reproductive modes in animals

• Reproductive modes in animals

• Methods of fertilization

• External fertilization fertilization of egg
  outside of female body

• Broadcast spawning of marine invertebrates such
  as clams

• Many fish and amphibians

• Internal fertilization fertilization of egg
  within female body

• Birds, mammals, some fish, reptiles, amphibians

How are new organisms produced?
9
Reproductive modes in animals

• Reproductive modes in animals

• Development modes after fertilization

• Oviparity eggs fertilized internally but
  develop outside mothers body

• birds, some reptiles (e.g. turtles), most bony
  fish (e.g. sunfish), most insects (e.g.
  butterflies)

• Viviparity eggs fertilized internally and
  develop internally, relying on nutrition from
  females blood

• mammals and many cartilaginous fish (e.g. sharks)

• Ovoviviparity fertilized eggs retained within
  mother and develop internally, relying on yolk
  for nutrition

• Some bony fish (e.g. guppies), many reptiles
  (e.g. garter snakes)

How are new organisms produced?