GENETIC LOAD AND THE MATING SYSTEM IN HOMOSPOROUS FERNS.

The mutational genetic load was calculated assuming mutation-selection-inbreeding equilibrium and applied to homosporous ferns. Diploid species with past inbreeding should have a low genetic load while outcrossers should have a high genetic load. These predictions are consistent with the bimodal pattern of genetic load found in 18 diploid homosporous fern species. The prediction that tetraploids should have a low genetic load is also consistent with estimates of genetic load in several species.