Climate VS soil factors in local adaptation of two common plant species

10 páginas, 3 figuras y 2 tablas. -- Copyright by the Ecological Society of AmericaEvolutionary theory suggests that divergent natural selection in heterogeneous environments can result in locally adapted plant genotypes. To understand local adaptation it is important to study the ecological factors responsible for divergent selection. At a continental scale, variation in climate can be important while at a local scale soil properties could also play a role. We designed an experiment aimed to disentangle the role of climate and (abiotic and biotic) soil properties in local adaptation of two common plant species. A grass (Holcus lanatus) and a legume (Lotus corniculatus), as well as their local soils, were reciprocally transplanted between three sites across an Atlantic–Continental gradient in Europe and grown in common gardens in either their home soil or foreign soils. Growth and reproductive traits were measured over two growing seasons. In both species, we found significant environmental and genetic effects on most of the growth and reproductive traits and a significant interaction between the two environmental effects of soil and climate. The grass species showed significant home site advantage in most of the fitness components, which indicated adaptation to climate. We found no indication that the grass was adapted to local soil conditions. The legume showed a significant home soil advantage for number of fruits only and thus a weak indication of adaptation to soil and no adaptation to climate. Our results show that the importance of climate and soil factors as drivers of local adaptation is species-dependent. This could be related to differences in interactions between plant species and soil biota.We thank all other members of the TLinks team for their contribution to the project and especially Franziska Leuenberger, Blanka Divisˇova´ , Alex Brook, and Victoria Chapman for technical assistance and Henk Duyts for identifying nematodes. We thank two anonymous reviewers for helpful comments on the manuscript. This project was supported by the Swiss Federal Office for Education and Science (Project 01.0086 to H. Mu¨ ller-Scha¨ rer) to join the TLinks project, EVK2-CT- 2001-00123, funded by the Framework V Program of the European Community.Peer reviewe