Inter-population variation in mating system and late-stage inbreeding depression in Magnolia stellata

Inbreeding has the potential to cause evolutionary changes in populations, although these changes are likely to drive populations to extinction through inbreeding depression and reductions in genetic diversity. We investigated the mating system and late-stage inbreeding depression (δ) in 10 populations of Magnolia stellata using nine microsatellite markers and evaluated the effects of population size and the degree of population isolation through inbreeding and inbreeding depression on the persistence of populations. The outcrossing rates were very similar (~0.7) among populations, but the correlations of paternity, fractions of biparental inbreeding and inbreeding coefficients at the seed stage (FS) varied among populations, suggesting that the level of outcrossing was similar among populations, while the quality of it was not. A significant negative correlation was detected between FS and population size. The average value of δ was 0.709, and the values in six of the 10 populations we...