Experiments on Plant Hybridization

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The seven characteristics observed by Mendel

Experiments on Plant Hybridization[1] (German: Versuche über Pflanzen-Hybriden) is a seminal paper written in 1865 by Gregor Mendel, an Augustinian friar considered to be the founder of modern genetics. The paper was the result after years spent studying genetic traits in Pisum sativum, the pea plant. Mendel read his paper to the Natural History Society of Brünn. It was published in the Proceedings of the Natural History Society of Brünn the following year.

In his paper, Mendel compared seven discrete characters:

  • Color and smoothness of the seeds (yellow and round or green and wrinkled)
  • Color of the cotyledons (yellow or green)
  • Color of the flowers (white or violet)
  • Shape of the pods (full or constricted)
  • Color of unripe pods (yellow or green)
  • Position of flowers and pods on the stems
  • Height of the plants (short or tall)

Through experimentation, Mendel discovered that one inheritable trait would invariably be dominant to its recessive alternative. In his paper, Mendel laid out the genetic model later known as Mendelian inheritance or Mendelian genetics. This model provided an alternative to blending inheritance, which was the prevailing theory at the time. Mendel's work received little attention from the scientific community and was largely forgotten. It was not until the early 20th century that Mendel's work was rediscovered and his ideas used to help form the modern synthesis.

In 1936, the statistician R.A. Fisher used a chi-squared test to analyze Mendel's data and concluded that Mendel's results with the predicted ratios were far too perfect, indicating that adjustments (intentional or unconscious) had been made to the data to make the observations fit the hypothesis.[2] Later authors have claimed Fisher's analysis was flawed, proposing various statistical and botanical explanations for Mendel's numbers.[3] It is also possible that Mendel's results are "too good" merely because he reported the best subset of his data — Mendel mentioned in his paper that the data was from a subset of his experiments.[4]

References[edit]

  1. ^ Mendel, G., 1866, Versuche über Pflanzen-Hybriden. Verh. Naturforsch. Ver. Brünn 4: 3–47 (in English in 1901, J. R. Hortic. Soc. 26: 1–32)
  2. ^ Fisher, R. A. (1936). "Has Mendel's work been rediscovered?". Annals of Science 1 (2): 115–126. doi:10.1080/00033793600200111.  edit
  3. ^ Sturtevant, A. H. (2001). A History of Genetics. Cold Springs Harbor, New York: Cold Springs Harbor Laboratory Press. pp. 13–16. ISBN 0-87969-607-9. 
  4. ^ Fairbanks, D. J.; Rytting, B. (1 May 2001). "Mendelian Controversies: A Botanical and Historical Review". American Journal of Botany 88 (5): 737–752. doi:10.2307/2657027. ISSN 0002-9122. PMID 11353700.  edit

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