Microsatellite analysis of seed dispersal and parentage of saplings in bur oak, Quercus macrocarpa

Abstract

Microsatellite analysis was used to examine parentage and spatial distributions of 62 adult bur oaks Quercus macrocarpa, and 100 saplings in a single stand. Using genotypes scored by PCR products at four microsatellite loci, we determined that 94 saplings matched at least one parent in the stand. Saplings often occur as dense clusters of half‐sibs around the presumed maternal parent, and only four adults were seed parents to a large proportion of the saplings sampled. A stump apparently was the seed parent of the largest cluster of half‐sibs, which occupied a sizeable light gap opened up by the death of their maternal tree. Approximately half of the saplings appeared to have grown from seeds that had not been removed after falling from the tree, and half from seeds that were dispersed beyond the crown of their maternal parent. Long‐distance seed dispersal may be more common than has been previously reported. Extremely high levels of long‐distance pollination were indicated, and pollen donors within the stand were generally distributed randomly around maternal trees. More than half of the saplings had paternal parents outside of the stand. This study demonstrates the utility of microsatellite analysis for studying mating systems, seed dispersal and seedling establishment in natural plant populations.

Spruce colonization at treeline: where do those seeds come from?

“…After Dow and Ashley (1996) assumptions, we were able to distinguish between pollination and dissemination events. Juveniles with one assigned parent are considered the result of gene flow via pollen from outside, whereas juveniles with no detected parents are the result of gene flow via seed from outside.…”

“…The proportion of juveniles with no identified parents and with only one identified parent represent, respectively, an estimate of seed and pollen gene flow from outside the study area (Bacles et al, 2006). Then, we used the assumptions postulated by Dow and Ashley (1996) to determine pollen and seed movements inside the sampling area. When only one parent matched a juvenile in the stand, this adult was considered to be the mother tree, whereas when a compatible parent pair was found, the closest parent was considered the mother tree whereas the farthest was considered the father tree.…”

“…For plant species, genetic markers primarily have been used to measure effective pollen dispersal and relative male fertility by paternity analysis. Despite the importance of pollination dynamics, fitness of adult plants depends on seedling establishment (Dow and Ashley, 1996). Therefore, the assessment of parentage of established seedlings is the only approach that allows documentation of genetically relevant dispersal events, the so called 'effective' dispersal of pollen and seeds (Cain et al, 2000;Hardesty et al, 2006).…”

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

“…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).…”

“…Highly polymorphic codominant markers such as microsatellites are increasingly used to study gene flow based on exclusion probabilities (Byrne et al 1996;Dow and Ashley 1996;Streiff et al 1998;Gerber et al 2000). This kind of marker has been developed for Eucalyptus (Brondani et al 1998) and could be used to test the breeding system in seed orchards.…”