Fertility Variation in Pinus sylvestris: A Test of Sexual Allocation Theory

Sexual allocation theory assumes trade-offs and negative genetic correlations between male and female allocation in hermaphrodite plants. We tested this assumption by studying variation in male and female fertility in two experimental populations of Pinus sylvestris. In these populations, the genotypes have been vegetatively replicated, which allowed separation of the genetic and environmental components of variation. The genetic components of variation accounted for 36% of the total variation in pollen production in the two populations, and for 54% of cone production. As assumed by sexual allocation theory, the genetic correlation of pollen and cone production was negative in both populations (-0.59 and -0.15). However, positive environmental correlations between these traits (0.43 and 0.45) resulted in no phenotypic correlation in one population and a positive phenotypic correlation in the other.