Niche differentiation between diploid and polyploids is often inferred based on differences in patterns geographic occurrence, but has seldom been tested in the field. Because polyploids may be recently formed, range limits among them are alternatively argued to result from dispersal limitation rather than reflecting broad patterns of environmental tolerance. Using a series of common gardens distributed within and beyond the elevation ranges of diploid and polyploid Claytonia perfoliata (Portulacaceae) in the Sierra Nevada mountains, I tested for local adaptation by comparing plant performance within and beyond the elevational range of each cytotype. Although designed to address local adaptation of cytotypes, this study also represents a transplant of species within and beyond their geographic ranges.
Results/Conclusions
Performance of cytotypes was compared using a series of planned contrasts. Comparisons of germination and biomass for transplants within and beyond the elevational range of each cytotype provided mixed support for local adaptation. Some cytotypes performed best within their naturally occurring elevation range, while performance of other cytotypes was not associated with native elevational range. Some cytotypes exhibited no decline in performance beyond their elevational range potentially indicating disequilibrium between range and adaptation. Relative performance across sites was similar among some cytotypes, a pattern suggestive of niche conservatism within the closely related members of this polyploid complex. .
