Patterns of pollen flow and genetic differentiation among pollen pools in Quercus salicina in a warm temperate old-growth evergreen broad-leaved forest

Abstract

Paternity analysis and analysis of molecular variance were used to determine patterns of pollen flow and genetic differentiation among pollen pools in Quercus salicina in an 11.56-ha plot in a temperate old-growth evergreen broad-leaved forest. The genotypes at seven microsatellite loci were determined for 111 adult trees and 276 seeds collected from under eight seed parents. The proportion of pollen flow from outside the plot (further than 100 m) was 52.2%, indicating that long-distance pollen flow occurred frequently in this species, as observed in other Quercus species. The pollen pools from inside and outside the plot differed genetically, and genetic structure was detected in the population of adult trees within the plot. Therefore, long-distance pollen flow from outside the plot may introduce new or low-frequent alleles, and increase genetic diversity in this population. However, the actual average distance of pollen flow within the plot was significantly shorter than the average potential distance, and negative exponential curves explained well the frequencies of matings as functions of the distance between parents, as found in other Quercus species. The genetic composition of pollen pools differed among the eight seed parents. The genetic differentiation of pollen pools between the seed parents showed significant positive correlation with the spatial distance between them, indicating that neighboring seed parents tend to accept similar pollen pools, probably because matings are frequently mediated by pollen transported over short distances.