Phenotypic responses to light, water, and nutrient conditions in the allopolyploid and its parent species and : Does the allopolyploid outrange its parents?

Polyploid species possess more than two sets of chromosomes and may show high gene redundancy, hybrid vigor, and masking of deleterious alleles compared to their parent species. Following this, it is hypothesized that this makes them better at adapting to novel environments than their parent species, possibly due to phenotypic plasticity. The allopolyploid and its parent species . and . were chosen as a model system to investigate relationships between phenotypic plasticity, fitness, and genetic variation. Particularly, we test if . is more plastic, show higher genetic diversity, and/or have higher fitness than its parent species. Wild Norwegian populations of each species were analyzed for phenotypic responses to differences in availability of nutrient, water, and light, while genetic diversity was assessed through analysis of AFLP markers. showed a higher level of phenotypic plasticity and higher levels of genetic diversity than the two other species, probably related to its outbreeding reproduction strategy. Furthermore, a general positive relationship between genetic diversity and phenotypic plasticity was found. Low genetic diversity was found in the inbreeding . . Geographic spacing of populations might explain the clear genetic structure in . , while the lack of structure in . could be due to coherent populations. Fitness measured as allocation of resources to reproduction, pointed toward . having lower fitness under poor environmental conditions. , on the other hand, showed tendencies toward keeping up fitness under different environmental conditions.