Proximity-dependent pollen performance in Silene vulgaris.
OBJECTIVE
Pollen and seed dispersal in herbaceous insect-pollinated plants are often restricted, inducing strong population structure. To what extent this influences mating within and among patches is poorly understood. This study investigates the influence of population structure on pollen performance using controlled pollinations and genetic markers.


METHODS
Population structure was investigated in a patchily distributed population of gynodioecious Silene vulgaris in Switzerland using polymorphic microsatellite markers. Experimental pollinations were performed on 21 hermaphrodite recipients using pollen donors at three spatial scales: (a) self-pollination; (b) within-patch cross-pollinations; and (c) between-patch cross-pollinations. Pollen performance was then compared with respect to crossing distance.


RESULTS
The population of S. vulgaris was characterized by a high degree of genetic sub-structure, with neighbouring plants more related to one another than to distant individuals. Inbreeding probably results from both selfing and biparental inbreeding. Pollen performance increased with distance between mates. Between-patch pollen performed significantly better than both self- and within-patch pollen donors. However, no significant difference was detected between self- and within-patch pollen donors.


CONCLUSIONS
The results suggest that population structure in animal-pollinated plants is likely to influence mating patterns by favouring cross-pollinations between unrelated plants. However, the extent to which this mechanism could be effective as a pre-zygotic barrier preventing inbred mating depends on the patterns of pollinator foraging and their influence on pollen dispersal.
Glaettli
Mélanie
M
Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2. glaettli@botany.utoronto.ca
Pescatore
Luca
L
Goudet
Jérôme
J
D001947:Breeding; D005819:Genetic Markers; D018895:Microsatellite Repeats; D011058:Pollen / Q000254:growth & development / Q000502:physiology*; D012098:Reproduction; D029751:Silene / Q000502:physiology*
D005819:Genetic Markers