Polyembryony

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Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg (in humans, identical twins). Polyembryony occurs regularly in many plants and animals. The nine banded armadillo, for instance, usually gives birth to four identical young. Polyembryony is best known among parasitoid insects of the order Hymenoptera, families Encyrtidae, Dryinidae, Platygasteridae and Braconidae. The term is also used in botany to describe the phenomenon of two seedlings emerging from one seed.

In plants, polyembryony often gives rise to the enigma of a single offspring.[1] The mechanism underlying this phenonomenon is programmed cell death (PCD) which removes all but one embryo.

A more striking example of the use of polyembryony as a competitive reproductive tool is found in the parasitoid Hymenoptera family Encyrtidae. The progeny of the splitting embryo develop into at least two forms, those that will develop into adults and those that become a type of soldier, called precocious larvae. These latter larvae patrol the host and kill any other parasitoids they find with the exception of their siblings, usually sisters.[2]

See also[edit]

Polyembryony also occurs in Bryozoa.

References[edit]

  1. ^ Filonova LH, von Arnold S, Daniel G and Bozhkov PV (October 2002). "Programmed cell death eliminates all but one embryo in a polyembryonic plant seed". Nature 9 (10): 1057–1062. doi:10.1038/sj.cdd.4401068. 
  2. ^ N.E. Beckage; S.N. Thompson; B.A. Federici (1990). Parasites and Pathogens of Insects", Vol. 1: Parasites, Vol. 2: Pathogens. Academic Press. San Diego. pp. 2 Volumes. ISBN 0-412-07401-X. Retrieved 22 January 2011. 

External links[edit]

1997 Craig, S.F., L.B. Slobodkin, and G. Wray. The 'Paradox' of Polyembryony: A review of the cases and a hypothesis for its evolution. Evolutionary Ecology, 11 (2): 127-143.