Plant Genome Structure

Evolutionary Relatedness

Comparative Genome Mapping

Physical and Genetic Distances

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Evolutionary Relatedness

Many papers have been published in which molecular data is used to assess the evolutionary relatedness of plant species. The typical experiment begins with a large collection of cultivars or species. These samples are then analyzed by hybridization with RFLP clones or more recently by the PCR-RAPD amplification. The similarity of each pair of samples is measured by calculating the number of common bands or amplification products. One estimator was developed by Nei and Li (PNAS, 1979, 76;5269-5273). The formula is:

F = 2nXY/(nX + nY)

where nX and nY are the total number of fragments for sample X and Y and nXY is the number of fragments shared by the samples. Data is normally collected for a relatively large number of hybridizations or PCR-RAPD amplifications. The similarity data is then used in a cluster analysis to develop dendrograms which show the molecular relatedness of the species.

These types of analyzes can:

  • provide independent support to previous phylogenetic and evolution hypotheses
  • identify gene pools within a genus
  • estimate genetic diversity within a genus
  • provide necessary data to select appropriate parents for a molecular mapping project

Copyright © 1998. Phillip McClean