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An Introduction to Zoology:  Chapter 5
An Introduction to Zoology: Chapter 5
Published by The Lone Ranger
08-05-2008
Default Parthenogenesis


Some animals can reproduce through parthenogenesis. Parthenogenesis occurs when a female produces an ovum (it can be either haploid or diploid) that can grow into a new individual (which may or may not be genetically identical to its mother) without being fertilized by a spermatozoan.

In some insects (Phylum Arthropoda), for example, a fertilized ovum develops into a diploid female, while unfertilized ova develop into haploid males. Animals with this sort of genetics are referred to as haplodiploid, because individuals of one sex are haploid and individuals of the other sex are diploid. Honeybees are an example of insects that are haplodiploid. Male honeybees, since they’re haploid, produce spermatozoa that are genetically-identical to themselves; female honeybees, since they’re diploid, produce ova that are not genetically-identical to themselves. (This has important consequences for honeybee behavior.)

Parthenogenesis is not limited to “simple” animals. It has been observed in fishes, reptiles, and birds. In fact, there are some lizard species in the genus Cnemidophorus in which males are not known to occur. Every member of the species is a female, and all reproduction is through parthenogenesis. (This means that every daughter is a clone of her mother.)


Two
Cnemidophorus uniparens engaging in “pseudocopulation.” Males are not known to
occur in this species and reproduction is through parthenogenesis. “Copulation” with
another lizard seems to stimulate a female to ovulate. This vestigial sexual behavior
provides strong evidence that
C. uniparens evolved fairly recently from a sexually-reproducing species.


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Thanks, from:
Corona688 (08-10-2008), Ensign Steve (08-05-2008)
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