An experimental test of local adaptation among cytotypes within a polyploid complex

Area of Science:

• Evolutionary biology
• Plant sciences
• Ecology

Background:

• Polyploid species often exhibit distinct geographic distributions and broader ecological niches than their diploid relatives.
• The drivers of these range differences, whether local adaptation or dispersal limitations, remain under-investigated in field experiments.

Purpose of the Study:

• To experimentally test whether geographic range differences in the Claytonia perfoliata complex are driven by local adaptation or other ecological factors.
• To assess the fitness and performance of different cytotypes across their elevational ranges.

Main Methods:

• Conducted three-year field transplant experiments with five cytotypes of the Claytonia perfoliata complex across their elevational gradients.
• Monitored germination success, biomass accumulation, and overall fitness of transplanted cytotypes within and beyond their native ranges.

Main Results:

• Evidence for local adaptation was found, with higher germination and biomass within the natural range for most cytotypes in at least one study year.
• Fitness varied annually and across environments, with some cytotypes performing better outside their native range, indicating temporal variability.
• No general polyploid advantage was observed, but a highly fit hexaploid cytotype, noted as invasive, showed superior performance across environments.

Conclusions:

• Geographic range variations within the Claytonia perfoliata complex are likely shaped by local adaptation of cytotypes.
• While not a universal rule, certain polyploid cytotypes can exhibit exceptional fitness, contributing to ecological differentiation within polyploid complexes.
• Findings support the role of ecological differentiation in the diversification of polyploid plant complexes.