Tippery, Nicholas , Les, Donald .
Evidence for natural hybridization between two dioecious North American Nymphoides species (N. aquatica and N. cordata; Menyanthaceae).
Outcrossing in the floating-leaved aquatic plant genus Nymphoides (about 50 species) is promoted by various sexual conditions including dimorphic heterostyly (most species) and dioecy (four species). The eastern North American N. aquatica and N. cordata are dioecious sibling species that differ by relatively minor morphological traits including adventitious root form, leaf texture, and overall size. Although these features distinguish the majority of individuals, the existence of morphological intermediates within broadly overlapping ranges confounds the identification of some specimens. In addition, similar floral morphology, reliance on outcrossing, and broadly overlapping ranges contribute to the likelihood of pollen transfer between N. aquatica and N. cordata. We undertook a molecular phylogenetic study using nuclear (ITS) and chloroplast (matK/trnK) sequence data obtained from individuals collected across the ranges of both species, in order to ascertain the distinctness of N. aquatica and N. cordata and to investigate their potential for hybridization. Our results indicated that most individuals of N. aquatica and N. cordata were readily identifiable to one or the other species, and these corresponded to reciprocally monophyletic groups. However, some individuals collected within the sympatric range of N. aquatica and N. cordata were revealed by molecular cloning to be interspecific hybrids. These data are consistent with the existence of two North American Nymphoides species that are predominantly distinct morphologically but nonetheless occasionally produce genetically intermediate hybrids.
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1 - University Of Wisconsin-Whitewater, Department of Biological Sciences, 800 W Main St, Whitewater, WI, 53190
2 - University Of Connecticut, Department Of Ecology & Evolutionary Biology, 75 N. Eagleville Road, Unit 3043, Storrs, CT, 06269-3043, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell A/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 1:45 PM