Are enzyme loci selectively neutral in haploid populations of nonvascular plants?

Enzyme data from 12 previously published studies of haploid bryophyte popul ations were subjected to tests of selective neutrality and population equil ibrium. Altogether 280 samples were tested using the Ewens-Watterson test, the Ewens exact test, and Chakraborty's test. The Ewens-Watterson and the E wens exact tests revealed neutrality in 84.6% of the cases, whereas the Cha kraborty test revealed neutrality in 100% of the cases. Neutrality may thus explain the relatively high amounts of genetic variation found in these or ganisms. Possible hidden population substructuring and nonrandom field samp ling of genotypes in many of the studies could make Chakraborty's test more reliable than the two others.