Allozyme diversity in Leavenworthia populations with different inbreeding levels

Levels of allozyme diversity were studied in five species of the annual plant genus Leavenworthia. The breeding systems of the populations were also characterized in terms of measures of autogamous seed-set and self-fertility. The populations that appeared more inbreeding by these criteria also tended to have lower within-population gene diversity (HS) values, but there was nevertheless considerable allozyme variability in two of the four sets of inbred populations studied. Comparing the outcrosser L. stylosa and the related inbreeders L. uniflora and L. torulosa the reduction in diversity associated with inbreeding was very high, as no variants were seen within populations of the inbreeders. In L. crassa and L. alabamica, the reduction was lower, but correcting for the fact that this comparison is over less extreme selfing rate differences, it is estimated that the difference between extreme inbreeding and outcrossing populations of L. crassa considerably exceeds twofold. These results are compared with published studies within closely related taxa with different inbreeding levels. The effect of inbreeding on allozyme diversity is consistently larger than has been estimated from comparisons of unrelated species.