Data for Rapid phenotypic differentiation and local adaptation in Japanese knotweed s.l. (Reynoutria japonica and R. × bohemica, Polygonaceae) invading novel habitats

PREMISE: Many plant invaders like the Japanese knotweeds are thought to
colonize new habitats with low genetic diversity. Such species provide an
opportunity to study rapid adaptation to complex environmental conditions.
METHODS: Using replicate reciprocal transplants of clones across three
habitats, we described patterns of phenotypic response and assessed degree
of local adaptation. KEY RESULTS: We found plants from beach habitats had
decreased height, number of leaves, leaf area, and biomass allocation to
roots and shoots compared to plants from marsh and roadside habitats when
grown in their home habitat. In the marsh habitat, marsh plants were
generally larger than beach plants, but not different from roadside
plants. There were no differences among plants from different habitats
grown in the roadside habitat. Despite this evidence of differentiation in
beach and marsh habitats, we found mixed evidence for local adaptation. In
their “home site” plants from the marsh habitat had greater biomass than
plants from the beaches but not compared to plants from roadsides. Biomass
comparisons in other habitats were either maladaptive or not significant.
However, plants from the roadside had greater survival in their “home
site” compared to foreign plants. There were no differences in survival in
the other habitats. CONCLUSIONS: We found phenotypic differentiation
associated with habitats despite the low reported genetic diversity for
these populations. Our results partially support the hypothesis of local
adaptation in marsh and roadside habitats. Identifying whether these
patterns of differentiation result from genetic or heritable non-genetic
mechanisms will require further work.