Data from: Evolution of nickel hyperaccumulation and serpentine adaptation in the Alyssum serpyllifolium species complex

Metal hyperaccumulation is an uncommon but highly distinctive adaptation
found in certain plants that can grow on metalliferous soils. Here we
review what is known about evolution of metal hyperaccumulation in plants
and describe a population-genetic analysis of the Alyssum serpyllifolium
(Brassicaceae) species complex that includes populations of
nickel-hyperaccumulating as well as non-accumulating plants growing on
serpentine (S) and non-serpentine (NS) soils, respectively. To test
whether the S and NS populations belong to the same or separate closely
related species, we analysed genetic variation within and between four S
and four NS populations from across the Iberian peninsula. Based on
microsatellites, genetic variation was similar in S and NS populations
(average Ho=0.48). The populations were significantly differentiated from
each other (overall FST=0.23), and the degree of differentiation between S
and NS populations was similar to that within these two groups. However,
high S versus NS differentiation was observed in DNA polymorphism of two
genes putatively involved in adaptation to serpentine environments, IREG1
and NRAMP4, whereas no such differentiation was found in a gene (ASIL1)
not expected to play a specific role in ecological adaptation in A.
serpyllifolium. These results indicate that S and NS populations belong to
the same species and that nickel hyperaccumulation in A. serpyllifolium
appears to represent a case of adaptation to growth on serpentine soils.
Further functional and evolutionary genetic work in this system has the
potential to significantly advance our understanding of the evolution of
metal hyperaccumulation in plants.