ECOLOGICAL DIFFERENTIATION IN PERENNIAL, OCTOPLOID SPECIES OF FRAGARIA

Abstract

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.