Parth

Parthenogenesis is the reproductive process by "which an unfertilized egg develops into a new
individual" (dictionary.com). During gametogenesis, the final polar body produced during meiosis
fuses with the ovum producing a diploid cell with identical chromosomes in each pair.

In reptiles and amphibians, it follows two general pathways:

1. MOST COMMON--all female offspring are produced by all female populations or species
(utilizing XY gametogenic sex determination because females have identical sex chromosomes,
  XX).
OR
2. VERY RARE--all male offspring are produced in bisexual populations and species (utilizing ZW
  gametogenic sex determination because males have identical sex chromosomes, ZZ)--called
  automatic parthenogenesis.

A third type in which a doubling of the chromosomes most likely occurred before meiosis (ZWZW) was
recorded in one specific individual snake of a bisexual species (Python molorus bivittatus--Burmese
python) produced female offspring.


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				Reptile and Amphibian Genetic and Non-Genetic Sex-Determination Factors

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	Quick Links Chromosomal (Gametogenic) Sex Determination Parthenogenesis: It's a Girl!...well, usually Natural Gender Reassignment (sex reversal) Temperature-Dependent Sex Determination

		Representative Species: Type 1 Parthenogenesis mourning gecko, Lepidodactylus lugubris; Indo-pacific gecko, Hemidactylus garnotii: whiptail lizards, Cnemidophorus velox; common blind snake, Ramphotyphlops braminus; also two gynogenic hybrid mole salamanders, Abystoma jeffersonium X A. laterale Type 2 Parthenogenesis timber rattlesnake, Crotalus horridus; and wandering garter snake, Thamnophis elegans vagrans

page last updated January 8, 2006 all images are the property of Randy G. Bradley-Campbell and may not be reproduced without permission

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