Linanthus parryae flower color variants, Short Canyon (near Ridgecrest), CA

Linanthus parryae flower variation

Early evolutionary biologists puzzled about this species, because populations could be found that contained only white flowers while other populations contained only blue flowers. Still other populations were mixed, like this one. Was it because of natural selection or was it due to random chance (genetic drift)? Experiments done by Schemske and Bierzychudek (2001) showed natural selection may play a role: white-flowering plants produced more seed than blue-flowering plants in wet years and the reverse occurred in dry years. Apparently because rainfall in the desert environment where these plants grow is so variable from year to year, both forms are maintained.

Schemske, D.W., and P. Bierzychudek. 2001. Perspective: Evolution of flower color in the desert annual Linanthus parryae: Wright revisited. Evolution 55:1269-1282.