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BTN 516 Developmental Biology
Bhawna Gupta
16610007
 Parthenogenesis is a natural form of asexual
reproduction in which growth and
development of embryos occur
without ferti...
 Apomictic parthenogenesis (or apomixis) involves
the suppression of meiosis so that offspring are produced
from unfertil...
 Automictic parthenogenesis: Automictic
parthenogenesis (or automixis), in contrast to apomixis,
retains meiosis with res...
 Gynogenesis is a form of parthenogenesis in which
sperm from a related bisexual species are required to
stimulate egg de...
 Hybridogenesis- Hybridogenesis
 is a hemiclonal mode of reproduction in that half of the genome
is transmitted sexually...
 Tychoparthenogenesis Parthenogenesis or Facultative
parthenogenesis is the term for when a female can
produce offspring ...
 Spontaneous origin- Spontaneous loss of sex may
occur through mutations in the genes involved in
the production of sexua...
 Infectious origin
A further possible mode of origin of parthenogenetic
lineages is through infection by inherited microo...
 Phylogenetic relationships between parthenogens and their
sexual relatives: the possible routes to parthenogenesis in
an...
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Parthenogenesis In animals

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Parthenogenesis In animals

  1. 1. BTN 516 Developmental Biology Bhawna Gupta 16610007
  2. 2.  Parthenogenesis is a natural form of asexual reproduction in which growth and development of embryos occur without fertilization.  In animals, parthenogenesis means development of an embryo from an unfertilized egg cell.  In the animal kingdom, 19 out of 34 phyla contain unisexual taxa.
  3. 3.  Apomictic parthenogenesis (or apomixis) involves the suppression of meiosis so that offspring are produced from unfertilized eggs by a mitosis-like cell division resulting in genetic identity to the mother, barring mutation.
  4. 4.  Automictic parthenogenesis: Automictic parthenogenesis (or automixis), in contrast to apomixis, retains meiosis with restoration of diploidy by duplication or fusion of the gametes produced by the female parent. Automixis occurs in many parthenogenetic stick insects and some weevils.
  5. 5.  Gynogenesis is a form of parthenogenesis in which sperm from a related bisexual species are required to stimulate egg development without contributing to the genetic composition of the offspring.  This particular parthenogenetic mechanism has been observed in unisexual Ambystoma species[8] as well as Glandirana rugosa
  6. 6.  Hybridogenesis- Hybridogenesis  is a hemiclonal mode of reproduction in that half of the genome is transmitted sexually while the other half is transmitted clonally. Sperm and egg nuclei fuse and paternal genes are expressed in the offspring, but only the maternal genome is transmitted to the next generation.
  7. 7.  Tychoparthenogenesis Parthenogenesis or Facultative parthenogenesis is the term for when a female can produce offspring either sexually or via asexual reproduction. Facultative parthenogenesis is extremely rare in nature.  Examples –mayflies, insects  Obligate Parthenogenesis- Obligate parthenogenesis is the process in which organisms exclusively reproduce through asexual means. Examples- Lizards, fishes
  8. 8.  Spontaneous origin- Spontaneous loss of sex may occur through mutations in the genes involved in the production of sexual forms and successful meiosis.  Hybrid Origin- Interspecific hybridization can disrupt meiosis and create opportunities for the selection of cytological processes that rescue egg production.  Contagious origin- Parthenogenetic lineages may arise secondarily from pre-existing parthenogenetic lineages as a result of incomplete reproductive isolation between sexuals and parthenogens.
  9. 9.  Infectious origin A further possible mode of origin of parthenogenetic lineages is through infection by inherited microorganisms. Induction of parthenogenesis is mainly accomplished by Wolbachia, a member of the Proteobacteria. It is known to induce parthenogenesis in parasitoid wasps such as Trichogramma as well as thrips and mites
  10. 10.  Phylogenetic relationships between parthenogens and their sexual relatives: the possible routes to parthenogenesis in animals: ROUTES TO PARTHENOGENESIS IN ANIMALS Article in Biological Journal of the Linnaean Society · May 2003  Parthenogenesis|Britannica.com

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