Evidence of local adaptation to fine‐ and coarse‐grained environmental variability inPoa alpinain the Swiss Alps

Abstract

Summary In the alpine landscape, characterized by high spatiotemporal heterogeneity and barriers, divergent selection is likely to lead to local adaptation of plant populations either through adaptive genetic differentiation or through phenotypic plasticity. The relative importance of these processes has rarely been investigated in relation to the spatial scale of environmental heterogeneity. In this study, we used reciprocal transplantation experiments of populations across nearby and distant field sites to shed light on these complementary processes. We reciprocally transplanted populations of the widespread alpine grass, Poa alpina, within and across regions in the Swiss Alps. We inferred local adaptation at the metapopulation level by comparing fitness of plants transplanted to their site of origin and to nearby or distant novel sites. Additionally, we measured specific leaf area (SLA) and performed selection analyses to investigate directional selection on mean trait value at each field site and on the degree of plasticity of this trait to assess whether plastic responses were adaptive. In parallel, all populations were genotyped with microsatellite markers to assess neutral molecular differentiation. Molecular differentiation was high among populations within and among regions, indicating restricted gene flow among P. alpina populations. Reproductive biomass was highest in individuals grown in their region of origin, revealing local adaptation to coarse‐grained environmental variability. Similarly, inflorescence height, associated with reproductive biomass, reflected adaptation to fine‐ and coarse‐grained environmental variability. Furthermore, we found evidence that plasticity in SLA across coarse‐grained habitats was correlated with plant fitness, suggesting that plasticity in this trait is adaptive. Synthesis. Our results revealed adaptive genetic differentiation between P. alpina populations in the Swiss Alps reflecting local adaptation. Furthermore, high phenotypic plasticity in SLA contributed to the maintenance of fitness homoeostasis across habitats. Hence, adaptive genetic differentiation and phenotypic plasticity play a complementary role for adaption of P. alpina to environmental heterogeneity in the Swiss Alps and both may be critical to mitigate local extinction risk under rapid climate change.

Genetic differentiation and plasticity interact along temperature and precipitation gradients to determine plant performance under climate change

“…genotype × environment interactions), but also result in differentiation in the degree of phenotypic plasticity (Kawecki & Ebert ; Hamann et al . ). While plastic variation between populations, reflected by the genotype × environment interaction, has been repeatedly demonstrated (reviewed e.g.…”

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

“…Therefore, the elevational gradient has been considered as the most important factor in studies on phenotypic variation of plant species in mountains (e.g. 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).…”

“…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. However, knowledge on variations in morphological traits and plant performance in natural populations along elevational gradients is also important to understand the role of natural selection in plant adaptation to alpine environments and plant phenotypic responses to such conditions (Clausen et al 1948;Gonzalo-Turpin and Hazard 2009;Bastida et al 2015).…”

High intraspecific phenotypic variation, but little evidence for local adaptation in Geum reptans populations in the Central Swiss Alps

“…Evidence for local adaptation has been found in a number of alpine plant populations (Gonzalo-Turpin and Hazard 2009;Fischer et al 2011;Giménez-Benavides et al 2011;Hamann et al 2016); however, an extensive meta-analysis and another recent study suggest that local adaptation may be less common than frequently assumed (Leimu and Fischer 2008;Hirst et al 2016). Extensive gene flow among populations has been recognized as a main hindrance for local adaptation (Kawecki and Ebert 2004).…”

“…Moreover, strong phenotypic plasticity is likewise common in alpine species, and has been shown to provide a potential advantage for the persistence and survival of alpine species in a heterogeneous environment (Stöcklin et al 2009;Frei et al 2014). While the relative role of these two non-mutually exclusive strategies (i.e., adaptive genetic differentiation and plasticity), as well as the conditions for their evolution under divergent selection, are theoretically well understood, empirical evidence is rather scarce (Baythavong 2011; Hamann et al 2016). The spatial grain size of environmental variation, defined by the degree of environmental variation as perceived by an individual plant across its dispersal distance, is likely to determine which of these mechanisms prevails (Alpert and Simms 2002;Pigliucci et al 2003;Kawecki and Ebert 2004).…”