ISOZYME ANALYSIS OF POPULATION-STRUCTURE AND DIVERSITY IN THE PUFFBALL SPECIES LYCOPERDON PYRIFORME

Isozyme analysis possesses predictive value and may reveal aspects of the natural history of a species that are not otherwise obvious. Worki ng on this premise, isozyme analysis was performed on Lycoperdon pyrif orme to shed light on the attributes of this species that most likely influence the distribution of genetic diversity observed among seven c ollection sites within the study region (i.e., central Arkansas, north eastern Kansas and northwestern Missouri). Forty-nine unique multilocu s isozyme phenotypes were identified from cultures isolated from immat ure glebal tissue of 310 basidiocarps collected from the surface of de caying logs (similar to one isozyme phenotype per log). Numerical and cluster analyses to determine similarity of phenotypes indicated that these group out randomly and not according to collection site. Further analyses of isozyme data were performed, grouping phenotypes together into populations according to collection site. Isozyme bands were par titioned by locus based on the assumption that these represent alleles and interpreted on the assumption that the dikaryotic mycelia of this puffball species are physiologically diploid. Nine of the eleven puta tive loci examined were polymorphic, with a mean of 3.6 alleles/polymo rphic locus. Mean heterozygosity for populations varied from 0.200 to 0.345, suggesting the possibility that outcrossing occurs in this spec ies. Unweighted pair group method cluster analysis displayed marginal grouping of populations based on geographic proximity. Genetic diversi ty statistics indicate that genetic differentiation among; populations is low (G(ST) = 0.122). Patterns of variation observed in this specie s suggest that gene flow has acted as a homogenizing force in this spe cies within the region sampled.