Balanced Polymorphism in Dactylis glomerata Sub-species woronowii

Abstract

A CASE of balanced polymorphism, involving a recessive gene causing albinism, in Dactylis glomerata sub-species judaica has been reported by Apirion and Zohary1. What appears to be the same phenomenon is now reported for another diploid sub-species, woronowii, a seed-sample (No. 24171) of which was made available to me by the Division of Plant Industry, C.S.I.R.O., Canberra. Albino seedlings appear with a frequency of 13.5 per cent in this sample, and it may be taken that one is dealing with a recessive allele which, because of the lethality it confers in the homozygote, is present in unexpectedly high proportion. Evidently some superiority is attached to the heterozygous condition, which probably displays itself through a greater competitive ability in the seedling stage or a greater reproductive capacity when mature. However, because of the changed environmental circumstances in which the material is now being grown this selective advantage may be altered or lost. These possibilities are being investigated.