R. Bacilieri et al., INTRASPECIFIC GENETIC-STRUCTURE IN A MIXED POPULATION OF QUERCUS-PETRAEA (MATT) LEIBL AND QUERCUS-ROBUR L, Heredity, 73, 1994, pp. 130-141
The intraspecific genetic structure of a mixed population of sessile a
nd pedunculate oak was studied in the Petite Charnie Forest, Sarthe, F
rance, using enzyme electrophoresis. Spatial structure was analysed by
calculating F-statistics and autocorrelations at different scales of
spatial subdivision of the population. F-statistics were also used to
compare the genetic structure of groups of trees subdivided according
to the phenology of flowering. Spatial organization of phenology of fl
owering was studied with autocorrelation methods. In both species, a h
ighly significant heterozygote deficiency was found at the population
level. Spatial genetic structure was at least partially responsible fo
r this deficiency, as demonstrated by the variations observed in F-sta
tistics in relation to the size of this population subdivision. The si
gnificance of the observed structure was confirmed by comparison with
a null hypothesis generated with the help of permutation analysis. We
suggest that the limited dispersal of pollen and/or seeds in the stand
gave rise to a family structure. The autocorrelation in phenology of
flowering found in both species could contribute to lower the neighbou
rhood size and then to increase the Wahlund effect. Autocorrelation an
alyses allowed us to show that heterogeneity of patterns of structure
among loci was present. Other possible causes of the genetic structure
and its heterogeneity are discussed.