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Page 45 · DO #4926 · 231_Rogers_Bx9FF8_r
- Collection
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David James Rogers (1918–2007) papers
- Item/Folder
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Manihot - Correspondence; Publication, 1972–1973
- Digital Object
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DO #4926,
page 45
- Collection-level dates
- 1948–1977
Page transcription
PP.40-53
INTERPRETATIONS OF THE SUBGRAPHS OF MANIHOT ESCULENTA
The following section is given for those interested in the detailed processes of decision on cultivar classification. The discussion contains much information about the very basic problems involved in classification of taxa whose relationships are known, or are thought to be, reticulate. While problems of reticulate relationships may be slightly different from one taxon to another, this discussion should clarify some of the methodological problems faced by taxonomists interested in the studies of such complexes. We do not know of any previous published discussion of the type given here, and feel that this one is of such significance that it must be included to interpret the results.
Since the print-out of the Graph Theory Clustering Program assembles and orders the information in progressive steps as the c-values (similarity measures between pairs of cultivars) decrease, it is possible to follow the interactions of each specimen in all the steps from beginning to end, so that the substantive knowledge of the taxonomist can be applied in continuously recurrent question-and-answer mode. At each level the membership of at least one cluster has altered, the similarity relationship (moat) to the subsequent cluster changed, and homogeneity of some of the clusters may have increased or decreased significantly.
In Manihot esculenta the problem is the classification of a highly complex cultivated species in which the relationships are reticulate, with multiple referrable associations or relationships. To indicate these, we have used the computer print-out in several ways as follows:
1. To Discover the Properties (Attributes) of the Species that are Correlated. The relevancy of the properties of the organisms making up natural taxa have been measured by the amount of correlation or association of the attributes employed. Since so little biological information is available for