TESTING HYPOTHESES OF FUNCTIONAL-RELATIONSHIPS - A COMPARATIVE SURVEYOF CORRELATION PATTERNS AMONG FLORAL TRAITS IN 5 INSECT-POLLINATED PLANTS

To test hypotheses on the evolution of functional relationships, pheno typic correlations among floral traits were estimated in five species of insect-pollinated plants. The species studied were wild radish (Rap hanus raphanistrum), canola (Brassica napus), phlox (Phlox divaricata) , dame's rocket (Hesperis matronalis), and black mustard (Brassica nig ra). Six floral traits were measured on each species. In three of the five species the correlations between the filaments and corolla tube w ere significantly greater than the other floral correlations. This res ult is consistent with the hypothesis that selection for proper anther placement to enhance pollination has increased the filament-corolla t ube correlations in these three species. In contrast, none of the spec ies showed evidence of selection for an optimal stigma placement; the correlations between the pistil and corolla tube lengths were not grea ter than the other floral correlations in any of the five species.