ECOLOGICAL DIFFERENTIATION IN PERENNIAL,OCTOPLOID SPECIES OF FRAGARIA

Plants of octoploid Fragaria (2n = 56) were collected from 19 natural sites supporting strawberry colonies in California, grown in a common greenhouse and analyzed for 25 quantitative traits and 2 enzyme systems. Inter-populational variation was measured by using analysis of variance and genetic identity techniques. Micro- and macro-environmental measurements were made at each site. Stepwise multiple regressions were completed on the morphological-environmental variations and the allozyme frequency-environmental variations. Clonal propagules were compared under three controlled environmental conditions. Octoploid Fragaria appears to have undergone considerable ecological differentiation. Significant amounts of inter-populational variation were observed in a number of polygenic and monogenic traits. Numerous significant correlations were found between environmental and character variations, and in many cases, only a few environmental variables were necessary to “explain” significant amounts of that variation. Inter-populational differences were also found in the abilities of plants to accumulate biomass and survive under salt, nutrient and shade stress. It has been suggested that ecological differentiation plays a minor role in determining the eco-geographical range of allopolyploids due to the effects of polyploidy on the generation of mutational and recombinational variability. Clearly, this has not been the case in Fragaria.