Phenotypic differentiation of the Solidago virgaurea complex along an elevational gradient: Insights from a common garden experiment and population genetics

Abstract

Plant species distributed along wide elevational or latitudinal gradients show phenotypic variation due to their heterogeneous habitats. This study investigated whether phenotypic variation in populations of the Solidago virgaurea complex along an elevational gradient is caused by genetic differentiation. A common garden experiment was based on seeds collected from nine populations of the S. virgaurea complex growing at elevations from 1,597 m to 2,779 m a.s.l. on Mt. Norikura in central Japan. Population genetic analyses with microsatellite markers were used to infer the genetic structure and levels of gene flow between populations. Leaf mass per area was lower, while leaf nitrogen and chlorophyll concentrations were greater for higher elevations at which seeds were originally collected. For reproductive traits, plants derived from higher elevations had larger flower heads on shorter stems and flowering started earlier. These elevational changes in morphology were consistent with the clines in the field, indicating that phenotypic variation along the elevational gradient would have been caused by genetic differentiation. However, population genetic analysis using 16 microsatellite loci suggested an extremely low level of genetic differentiation of neutral genes among the nine populations. Analysis of molecular variance also indicated that most genetic variation was partitioned into individuals within a population, and the genetic differentiation among the populations was not significant. This study suggests that genome regions responsible for adaptive traits may differ among the populations despite the existence of gene flow and that phenotypic variation of the S. virgaurea complex along the elevational gradient is maintained by strong selection pressure.

Variation of vegetative and floral traits in the alpine plant Solidago minuta: evidence for local optimum along an elevational gradient

“…Stöcklin et al 2009;Št'astná et al 2012;Kim and Donohue 2013;Scheepens and Stöcklin 2013;Gugger et al 2015;Hamann et al 2016;Stöcklin and Armbruster 2016;Sakurai and Takahashi 2016;Takahashi and Matsuki 2016). Plants can respond to elevational changes based on their morphological and physiological plasticity and through local adaptations (Hirano et al 2017). Alpine plant species, compared to lowland plants, have distinctly smaller overall size (e.g.…”

“…Neuffer and Bartelheim 1989;Hirano et al 2017) or reciprocal transplantation to plots located at different elevations (e.g. Gonzalo-Turpin and Hazard 2009;Hautier et al 2009;Scheepens et al 2010;Hamann et al 2016) are essential.…”

Polyphyletic Alyssum cuneifolium (Brassicaceae) revisited: Morphological and genome size differentiation of recently recognized allopatric taxa

“…The latter explanation was clearly confirmed in Heliosperma pusillum (Bertel et al, ). A study of phenotypic variation within the Senecio virgaurea complex along an elevational gradient has revealed that plants originating from higher elevations have larger flower heads and shorter stems (Hirano et al, ). However, the genetic differentiation in neutral genes between populations at different elevations turned out to be extremely low.…”

“…The influence of particular environmental conditions (a scree habitat, high elevation, and serpentine bedrock) on the morphological appearance of the Alyssum taxa under study can be addressed by common garden experiments. Simple cultivation under uniform conditions is frequently used to assess the performance of morphological traits or to detect genetically based phenotypic differentiation between cytotypes or morphotypes (e.g., Mráz et al, ; Bertel et al, ; Eliášová & Münzbergová, ; Hirano et al, ), but a detailed examination of the morphological effects of specific environmental factors would require thoroughly designed reciprocal transplant experiments (see e.g., Bastida et al, ; Yuan et al, ; Hamann et al, ).…”

“…(Bertel et al, 2016) and Senecio virgaurea Maxim. (Hirano et al, 2017), morphological differentiation between populations from high-alpine stands and their genetically related lower-elevation counterparts is attributed to phenotypic plasticity or genetically fixed adaptation to the local environment. The latter explanation was clearly confirmed in Heliosperma pusillum (Bertel et al, 2016).…”