Phenotypic plasticity and genetic diversity in a polyploid Arabidopsis complex

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
Arabidopsis suecica and its parent species A. arenosa and A. thaliana were
chosen as a model system to investigate relationships between phenotypic
plasticity, fitness and genetic variation. Particularly, we test if A.
suecica 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. Arabidopsis arenosa 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 were found in the inbreeding A. thaliana. Geographic spacing of
populations might explain the clear genetic structure in A. arenosa, while
the lack of structure in A. suecica could be due to coherent populations.
Fitness measured as allocation of resources to reproduction, pointed
towards A. arenosa having lower fitness under poor environmental
conditions. Arabidopsis suecica, on the other hand, showed tendencies
towards keeping up fitness under different environmental conditions.