Evidence for the hybrid origin of Nuphar x rubrodisca (Nymphaeaceae)
1998
Padgett, D.J. | Les, D.H. | Crow, G.E.
Plants intermediate in appearance between Nuphar microphylla and N. variegata (Nymphaeaceae) have long been assumed to be the result of hybridization. The evidence for this is based primarily on field observations of morphology, poor fruit production, close geographical proximity of presumed parent species, and limited pollen sterility data. Fertile populations of the same plants have also been documented. We employed multivariate analyses of morphology, pollen fertility studies, and random amplified polymorphic DNA (RAPD) markers to test the hypothesis that Nuphar x rubrodisca represents a natural interspecific hybrid between N. microphylla and N. variegata. Examination of 15 morphological characters demonstrated the intermediacy of N. x rubrodisca between N. microphylla and N. variegata, and the pollen data revealed a markedly lower mean pollen viability in N. x rubrodisca (23%) compared to the other two species (91 and 86%, respectively). Eight 10-mer primers produced 13 species-specific RAPD markers for N. microphylla and nine for N. variegata, with all 22 markers present in N. x rubrodisca. The data from RAPDs are concordant with morphology in implicating N. microphylla and N. variegata as parents of N. x rubrodisca.
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