Allozyme analysis, morphological characters, and histocompatibility relationships have revealed unexpected amounts of clonal diversity within and among populations of unisexual animals. Plant studies, likewise, have shown that genetic diversity exists in populations of plants that have restricted recombination. However, no work has been done which investigates the extent of genotypic diversity within and among populations of an obligate apomict.
This study surveyed 22 North American populations of Taraxacum officinale, an obligate gametophytic apomict. Over 20 individuals from each population were assayed electrophoretically for three enzyme systems representing five different migration zones. Seed colour was used to determine seven phenological classes that, when combined with the allozyme morphs, resulted in 47 discernible clones among 518 individuals sampled. Chromosome analysis revealed the ploidy level to be triploid in all cases.
The number of clones per population ranged from 1-13, with a mean of 5·0. Sixty-six per cent of the clones were restricted to single populations, and the mean number of populations containing a particular clone is 2·1. One widespread clone was found in all but three of the populations. Diversity values, expressed as clones per individual, indicate that T. officinale proved to be more genotypically diverse than other clonal plants previously studied. Spearman's Rank Correlation test failed to show a correlation of diversity with latitude or elevation.
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Lyman, J., Ellstrand, N. Clonal diversity in taraxacum officinale (compositae), an apomict. Heredity 53, 1–10 (1984). https://doi.org/10.1038/hdy.1984.58
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