Reproduction:

1
Reproduction

• The Continuity of Life

Reproduction
Sexual Reproduction
Asexual Reproduction
2
Methods Advantages Disadvantages
Sexual Internal fertilization Offspring less likely to have mutations show up Successful traits can be selected and failed traits can be prevented from passing on Does require a mate to reproduce Population increases are limited
Sexual External fertilization Offspring less likely to have mutations show up Successful traits can be selected and failed traits can be prevented from passing on Does require a mate to reproduce Population increases are limited
Asexual Budding Uniformity in offspring Can increase populations rapidly Does not require a mate for reproduction to take place Lack of diversity in offspring Because they reproduce offspring genetically identical to parents, the offspring inherit any mutations of the parent.
Asexual Regeneration Uniformity in offspring Can increase populations rapidly Does not require a mate for reproduction to take place Lack of diversity in offspring Because they reproduce offspring genetically identical to parents, the offspring inherit any mutations of the parent.
Asexual Fission Uniformity in offspring Can increase populations rapidly Does not require a mate for reproduction to take place Lack of diversity in offspring Because they reproduce offspring genetically identical to parents, the offspring inherit any mutations of the parent.
Asexual Parthenogenesis Uniformity in offspring Can increase populations rapidly Does not require a mate for reproduction to take place Lack of diversity in offspring Because they reproduce offspring genetically identical to parents, the offspring inherit any mutations of the parent.
3
Asexual Reproduction Genetically Identical
Offspring

• Budding
• Regeneration
• Fission
• Fragmentation
• Vegetative Propagation
• Parthenogenesis
• Cloning???

4
Budding

• New Organisms Arise as an Outgrowth from the
  Parent Organism
• Seen Mostly in Marine Animals
• Examples Include Sponges, Corals and Jellyfish

Coral Polyp Photo courtesy Jeffrey N. Jeffords
http//oceanworld.tamu.edu/students/coral/coral1.
htm
5
Regeneration

• This refers to the ability of some animals to
  re-grow severed parts.
• Some of these animals can also grow new organisms
  from the severed pieces (Segmented Worms and Sea
  Stars)

6
Fission

• This is the type of reproduction all prokaryotes
  go through. The DNA is copied, the cell enlarges
  and splits in 2. Both cells then have the ability
  to grow as large as the original cell.

7
Vegetative Propagation

• Asexual reproduction in plants when a piece of
  the original plant can result in another organism
  without seeds or spores.

8
Fragmentation

• When pieces of the parent organism are broken off
  and grow in to genetically identical organisms.

9
Parthenogenesis

• Offspring can arise from unfertilized eggs.
• Includes some Fish, Reptiles, Amphibians and
  Aphids.
• Most of these species can switch between Sexual
  and Asexual Reproduction.
• (depending on conditions)

http//aolsearch.aol.com/aol/imageDetails?invocati
onTypeimageResultsqueryphotosofparthenogenic
speciesimg
http//www.duke.edu/7Ejsr6/Hawaiipics/Rhampho.jpg
http//spot.colorado.edu/noyesr/TEACHING/480020F
all202002.20Biology20and20Evolution20of20Sex
/Gynogenesis.Poecilia.pdf
www.ag.ndsu.nodak.edu
10
WHY???

• Why would these organisms prefer asexual
  reproduction in stable conditions and sexual
  reproduction in more uncertain or less favorable
  conditions?

11
Imagine

• Imagine that a particular organism within a
  species lacks a certain gene (or ability to
  express a certain gene) necessary to break down a
  specific type of food, yet others of the same
  species within the population are able to break
  down that food.
• What happens if the uncertain or less favorable
  conditions lead to that being the primary food
  source?

12
Death

• The parent organism and all of their offspring
  produced through parthenogenesis would die!
• But, with the genetic diversity that comes from
  sexual reproduction the possibility of the
  offspring surviving is enhanced.