An apparent dimorphism in a sample of galls of the aphid Pemphigus populitransversus was substantiated by several univariate and multivariate methods. The initially observed dimorphism in gall shape could be substantiated by objective analyses and it was found that life history characteristics not originally noted were more dimorphic than measures of gall shape. Morphometric characters of stem mothers and alates also exhibited the dimorphism. Two measures of dip intensity, clustering, and ordination were employed to analyze six other samples. Three of these were found to be dimorphic in the sense established in the first locality, one turned out to be monomorphic, while the remaining two samples were nonallocable by the criteria established earlier. The importance of objective, logically consistent methods in analyzing apparent dimorphisms is stressed. The problems of establishing dimorphism in population samples are discussed in some detail, as are geographic variation of the dimorphism and of each morph. The possibility of a polythetically variable dimorphism over different localities or niches is discussed. Various biosystematic interpretations of the phenomena observed in this aphid are briefly enumerated.
No takes yet. Share an insight, caveat, or question.
Senner et al. (1974) studied this question.