Pollen dispersal inferred from paternity analysis in a mixed oak stand of Quercus robur L. and Q. petraea (Matt.) Liebl.

Abstract

Paternity analysis was used to determine the spatial distribution of male parents of 984 offspring collected from 13 identified mother trees in a natural stand of 5.76 ha and comprising 296 adult trees of Quercus petraea and Q. robur. For seven of the 13 maternal progeny arrays sampled, we found an excess of nearby matings and a preferential direction of pollination. For the remaining progeny arrays, no departure from random distribution of male parents was detected. A common trend among all families was a high percentage (averaging 65% for Q. robur and 69% for Q. petraea) of offspring that were pollinated by male parents from outside the study site. By pooling the data over all families, the average pollen dispersal curve within the stand was inferred and fitted to a negative exponential distribution. This model extrapolated for distances over the spatial scale of the study stand was insufficient to explain the high level of gene flow detected by the paternity analysis, suggesting a substantial level of long‐distance pollination events. The genetic composition of the pollen pools received by each maternal tree was compared and showed significant differentiation that could be attributed to differences in male reproductive success. By contrast, no significant differentiation between the pollen clouds from outside and inside the study stand was detected, suggesting genetic homogeneity between the surrounding forest and the study stand.

Gene flow estimation with microsatellites in a Malagasy seed orchard of Eucalyptus grandis

“…These observations confirmed that a few microsatellite markers were enough for paternity assignment. As shown for some other species, the large number of low-frequency alleles and their distributions, typical of microsatellite loci, positively influence the exclusion probabilities (Dow and Ashley 1998;Streiff et al 1999;Kameyama et al 2000;Konuma et al 2000). The overall outcrossing rate was high (96.7%) with no neighbouring effect.…”

“…Microsatellite data were used in the paternity analysis, using FaMoz software (S. Gerber, unpublished), which assigns paternity to a particular pollen donor, based on the likelihood-ratio method. The paternity assignment methods by exclusion procedures were detailed in Streiff et al (1999) and Gerber et al (2000). The multilocus genotype of the mothers and 349 potential fathers was known for each offspring.…”

“…The presence of bees in the area also suggested that pollen could be carried several kilometres and be exchanged in the hive (B. Vaissiere, personal communication). Microsatellite markers helped to demonstrate that long-distance pollen-flow within populations is relatively common for wind-pollinated species (Dow and Ashley 1996;Streiff et al 1999) and insectpollinated species (Chase et al 1996;Horskins and Turner 1999;Konuma et al 2000).…”

“…The contamination rate for a pine-seed orchard ranged from 14 to 74% (Pakkanen et al 2000). A common trend, among oak studies, is a high percentage (50-70%) of offspring with male parents outside the study sites (Dow and Ashley 1998;Streiff et al 1999). Konuma et al (2000) studied a low-density stand of insectpollinated (by stingless bees or Apis spp.)…”

Genetic evidence of reproductive isolation in a remote enclave of Quercus pubescens in the presence of cross-fertile species

“…A common observation is that a few tens percent of acorns result from pollination with immigrating pollen (e.g. Streiff et al 1999;Curtu et al 2009;Lepais and Gerber 2011;Buschbom et al 2011), and the immigration rate is relatively stable at the stage of established seedlings (Chybicki and Burczyk 2010;Lepais and Gerber 2011). This suggests that the population of Q. pubescens in Bielinek should experience a permanent oak pollen flow from the outside as well.…”