Effects of density and floral morph on pollen flow and seed reproduction of an endangered heterostylous herb,Primula sieboldii

Abstract

Summary 1We assessed the effects of population density and the spatial arrangement of genetically compatible mates on the seed set and pollen flow of a heterostylous, bumblebee-pollinated perennial, Primula sieboldii E. Morren (Primulaceae), by using an experimental population under natural pollination conditions. 2 We also examined the intermorph differences in the pollen dispersal distance and the frequency of self-and intramorph fertilization. 3 Seed set was significantly correlated with the number of opposite-morph flowers within 2 m in short-styled genets, and within 3 m in long-styled genets. 4 Mean pollen dispersal distance within the experimental population was 5.4 m, which was slightly shorter than that in a low-density population measured in a previous study (7.2 m). 5 The proportions of seedlings sired by the same morph or selfed were 10.2% and 3.0%, respectively, in long-styled mothers, compared with 1.9% and 0.0% among short-styled mothers. However, these differences were not statistically significant and no marked differences in pollen dispersal distances were observed between the two morphs. 6 Our results suggest that the presence of opposite-morph genets within several metres is essential for success of seed reproduction in P. sieboldii , irrespective of population density, and that stochastic deviation of the morph ratio in small populations is therefore likely to cause considerable reduction in seed set.

Neighbourhood density and genetic relatedness interact to determine fruit set and abortion rates in a continuous tropical tree population

“…In selfincompatible plants, fruit set would be expected to be lower when most mating is local and occurs between related individuals (Ishihama et al 2006). In this forest, Jacaranda neighbouring individuals within a 50 m radius are, on average, half siblings ( Jones & Hubbell 2006).…”

Fine-scale genetic structure within plots of Polygala reinii (Polygalaceae) having an ant-dispersal seed

“…While a comparative analysis of plant species with different life-history characteristics showed a less evident correlation between the pollination system and the strength of population genetic structuring (Degen et al 2001;Vekemans and Hardy 2004), some recent investigations based on paternity analysis using a highly polymorphic DNA makers demonstrated relatively limited pollen dispersal ranges in perennial herbs (e.g., the mean dispersal distance was 11 m in Centaurea corymbosa, Hardy et al 2004;and 5.4 m in Primura sieboldii, Ishihama et al 2006), suggesting that insect pollination could contribute to genetic structuring within a population. Therefore, further investigations are needed to clarify the pattern of pollen flow and to assess the influence of insect pollination on fine-scale genetic structure in P. reinii.…”

Floral colour versus phylogeny in structuring subalpine flowering communities

“…The abundance or density of a species within a community directly determines the amount of conspecific pollen that is available for pollination (Spigler & Chang 2008). Rare species will receive more interspecific pollen owing to the relative abundance of coflowering species and therefore may only persist in a community if they exhibit increased divergence in floral traits than do common species (Ishihama et al 2006). Recent models (Sargent & Otto 2006) and field studies (Gumbert et al 1999;Spigler & Chang 2008) indicate that rare species are under more pressure to have divergent floral traits and to evolve specialist pollination systems than are common species.…”