Post-pollination mechanisms in Nicotiana longiflora and N. plumbaginifolia: pollen tube growth rate, offspring paternity and hybridization |
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Authors: | Dulce M Figueroa-Castro Timothy P Holtsford |
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Institution: | (1) Division of Biological Sciences, University of Missouri, 202 Tucker Hall, Columbia, MO 65211-7400, USA;(2) Present address: Laboratorio de Ecología, Departamento de Biología, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco #186, Col. Vicentina, Del. Iztapalapa, C.P. 09340 México D.F., Mexico |
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Abstract: | In natural populations where interfertile species coexist, conspecific and heterospecific pollen can be delivered to the stigmas.
Post-pollination mechanisms might determine the seed siring success of different pollen donors within species as well as the
chances for hybridization between species. Nicotiana longiflora and N. plumbaginifolia occur in sympatry in Northwest Argentina, where they have overlapping flowering seasons and share floral visitors. We explored
(1) pollen tube growth rates for outcross versus self pollen in single-donor pollinations; (2) siring success of self versus
outcross pollen donors in competitive pollinations, and (3) possibilities for hybridization by performing two- (outcross conspecific
vs. heterospecific) and three-pollen donor (self vs. outcross vs. heterospecific) crosses. In N. longiflora, both pollen tube growth rate and siring success favored outcross pollen over self pollen and strong rejection of heterospecific
pollen. In N. plumbaginifolia, pollen tube growth rate was similar for self and outcross pollen, self pollen sired similar numbers of offspring than outcross
pollen and heterospecific pollen sired roughly the same number of progeny than self pollen. Results suggest that in natural
sympatric populations, interspecific crosses would likely lead to unidirectional hybridization with N. plumbaginifolia as the seed parent. |
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Keywords: | Competitive pollinations Cryptic self-incompatibility Paternity success Sympatry |
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