Chronological evaluation of the type specimens of Philippine apple snails (Pila spp.) by multivariate analysis
1995
Pagulayan, R.C. | Bonzo, D.I.B.C.
Nineteen museum specimens representing eight nominal species of ampullariids snail in the Philippines were examined. These are: Pila conica (Gray 1828), Pila luzonica (Reeve, 1856), Pila lubrica (Reeve, 1856), Pila vittata (Reeve, 1856), Pila ampullacea (Linnaeus, 1758), Pila moellendorffi (Kobelt 1911), Pila mainitensis (Kobelt 1911). Using the thirteen shell measurements taken, the nineteen museum specimens were subjected to three clustering methods, Average Linkage Method, Centroid Method, and Ward's Method. The result of the analysis, presented here in dendograms, revealed marked differences between the three methods in terms of the groupings or clusters produced. Of the thirteen shell measurements, factor analysis determined five measurements as more important. When the nineteen museum specimens were subjected again to the three clustering methods using only the five more important measurements determined by factor analysis, an apparent unity of the results was noted in terms of the near similarity of the three dendograms produced. This suggests that the dimensionality of the measurements can be reduced from thirteen to five without losing much pertinent information on the specimens
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