Genetic adaptation to soil acidification: experimental evidence from four grass species
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Anthropogenic acidification has reduced soil pH and released potentially toxic aluminium (Al) ions in many regions. This investigation examines whether increased acidity has caused genetic adaptation to acidic conditions within the grass species Elymus caninus, Poa nemoralis, Deschampsia cespitosa and D. flexuosa. We sampled tussocks (genets) of each species in two regions of southern Sweden, differing in their exposure to acidifying deposition. The tolerance of the genets was tested in a solution experiment with different pH and Al concentrations. Our data suggest that species found at lower pH field locations have a greater tolerance to low pH and high Al levels than species found on less acidic soils. Analysis of variance showed a significant average effect of population and (or) genet in most species; however, we found little evidence of genetic adaptation to acidic conditions at the regional, population and micro-site level. In fact, there was no consistent change in the ranking of populations or genets with varying pH or Al concentration. Based on these results, we hypothesize that phenotypic plasticity rather than genetic adaptation has been favoured as the predominant mechanism to cope with soil acidity in the four grass species.
KeywordsAluminium pH Tolerance Stress Local adaptation Genetic variation
We would like to thank Bengt Jacobsson for technical assistance in the greenhouse, Henrik Nilsson for help with laboratory work, and Mark van Kleunen and three anonymous reviewers for valuable comments on the manuscript. This research was supported by the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS).
- Falconer DS, Mackay TFC (1996) Introduction to quantitative genetics, 4th edn. Longman, HarlowGoogle Scholar
- Gananca JTF, Abreu I, Sousa NF, Pazi RF, Caldeira P, dos Santosi TMM, Costa G, Slaski JJ, de Carvalho MAAP (2007) Soil conditions and evolution of aluminium resistance among cultivated and wild plant species on the Island of Madeira. Plant Soil Environ 53:239–246Google Scholar
- Göransson P (2007) Genetic adaptation to soil acidification in four grasses. Ph.D. Dissertation, Department of Ecology, Lund University, SwedenGoogle Scholar
- Grime JP, Hodgson JG, Hunt R (1988) Comparative plant ecology: a functional approach to common British species. Unwin Hyman, LondonGoogle Scholar
- Lövblad G, Kindblom K, Grennfelt P, Hultberg H, Westling O (1995) Deposition of acidifying substances in Sweden. Ecol Bull 44:17–34Google Scholar
- Sambatti JBM, Rice KL (2006) Local adaptation, patterns of selection, and gene flow in the Californian serpentine sunflower (Helianthus exilis). Evol Int J Org Evol 60:696–710Google Scholar