Arabidopsis thalianapopulations show clinal variation in a climatic gradient associated with altitude

Abstract

Summary• Understanding the adaptive basis of life history variation is a central goal in evolutionary ecology. The use of model species enables the combination of molecular mechanistic knowledge with ecological and evolutionary questions, but the study of life history variation in natural environments is required to merge these disciplines.• Here, we tested for clinal variation in life history and associated traits along an environmental and altitudinal gradient in the model species Arabidopsis thaliana. Seventeen natural populations of A. thaliana were geo-referenced in northeastern Spain on a gradient in which precipitation increases but maximum spring temperature and minimum winter temperature decrease with altitude.• One hundred and eighty-nine genotypes from the 17 populations were grown under uniform controlled conditions. Variations in traits related to biomass allocation, fecundity, phenology and vegetative growth were tested for relationships with the altitude and climatic variables associated with the home sites. Aboveground mass, number of rosette leaves at bolting, developmental time and seed weight increased with the home site's altitude. Root allocation, vegetative growth during winter and number of seeds decreased with altitude.• We suggest that the differences among home sites provide clues to the variation in adaptive strategies associated with the climatic gradient. We compared these results with adaptations and clinal relationships reported for other species and with molecular mechanisms described in Arabidopsis.

The roles of genetic drift and natural selection in quantitative trait divergence along an altitudinal gradient in Arabidopsis thaliana

“…An adaptive decrease of rosette leaf number in the vegetative state with increasing altitude is consistent with phenotypic clines in the rate of leaf production during winter along altitude as reported for Iberian A. thaliana populations (Montesinos-Navarro et al, 2011). Similarly, leaf production and plant size decreased along latitude that is correlated with a decrease in temperature at a larger scale (Li et al, 1998).…”

“…Note that in these studies and in our study, rosette leaf number and rosette diameter after a defined period of time are used as measures of growth; in our study, rosette leaf number and rosette diameter after 3 weeks were not correlated with flowering time (Supplementary Table S5). Most other A. thaliana studies report rosette leaf number and rosette diameter at flowering, measures that often are highly correlated with flowering time and represent investment into growth vs reproduction (e.g., Mendez-Vigo et al, 2011;Montesinos-Navarro et al, 2011;Mendez-Vigo et al, 2013). The reduced rosette leaf number with higher altitudes in our study is likely associated with above ground biomass accumulation during vegetative growth as neither rosette diameter after 3 weeks nor leaf area decreased with altitude.…”

“…Similar trends have been reported as genetically based trait divergence within species, even when plants are sampled from regional altitudinal gradients where gene flow between populations can be high 1 (Monty and Mahy, 2009). For example, plant height or size and specific leaf area often decrease, whereas seed size often increases with altitude of origin within species when plants are grown in a common environment (Monty and Mahy, 2009;Montesinos-Navarro et al, 2011). The underlying mechanisms generating these high-altitude morphologies are still unclear, however, Körner (1999) proposed that small size at high altitude may allow plants to benefit from higher temperatures closer to the soil and thicker leaves may allow higher photosynthetic activity.…”

“…Ecologically relevant variation in A. thaliana and the genomic signature thereof has received substantial interest in recent years and numerous traits and genes displaying clinal variation along latitude have been identified (reviewed in Bergelson and Roux, 2010). Altitudinal clines in A. thaliana have thus far been described for populations from Spain, where population means of growth, flowering and seed traits changed with altitude of origin (Mendez-Vigo et al, 2011;Montesinos-Navarro et al, 2011). Such trait-altitude correlations are compatible with adaptive divergence along altitude; however, it is important to note that clines in trait means can also be caused by selectively neutral processes such as genetic drift through geographic isolation or by extinctionrecolonization dynamics (Vasemägi 2006;Kawakami et al 2011).…”

Constraints to and conservation implications for climate change adaptation in plants

“…Etterson 2004;Maron et al 2004;Uribe-Salas et al 2008;Bresson et al 2011;Montesinos-Navarro et al 2011;Chen et al 2012;Woods et al 2012). Reciprocal transplant and common garden experiments have been used to determine the degree of plastic versus heritable variation in clinal traits.…”