AOBPreview originally published online on February 16, 2007
Annals of Botany 2007 99(4):723-734; doi:10.1093/aob/mcm007
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Local Adaptation Enhances Seedling Recruitment Along an Altitudinal Gradient in a High Mountain Mediterranean Plant
Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos–ESCET, Tulipán s/n. 28933 Móstoles, Madrid, Spain
* For correspondence. E-mail: luis.gimenez{at}urjc.es
Received: 20 October 2006 Returned for revision: 17 November 2006 Accepted: 12 December 2006 Published electronically: 16 February 2007
Background and Aims: Germination and seedling establishment, which are critical stages in the regeneration process of plant populations, may be subjected to natural selection and adaptive evolution. The aims of this work were to assess the main limitations on offspring performance of Silene ciliata, a high mountain Mediterranean plant, and to test whether local adaptation at small spatial scales has a significant effect on the success of establishment.
Methods: Reciprocal sowing experiments were carried out among three populations of the species to test for evidence of local adaptation on seedling emergence, survival and size. Studied populations were located at the southernmost margin of the species' range, along the local elevation gradient that leads to a drought stress gradient.
Key Results: Drought stress in summer was the main cause of seedling mortality even though germination mainly occurred immediately after snowmelt to make the best use of soil moisture. The results support the hypothesis that species perform better at the centre of their altitudinal range than at the boundaries. Evidence was also found of local adaptation in seedling survival and growth along the whole gradient.
Conclusions: The local adaptation acting on seedling emergence and survival favours the persistence of remnant populations on the altitudinal and latitudinal margins of mountain species. In a global warming context, such processes may help to counteract the contraction of this species' ranges and the consequent loss of habitat area.
Key words: Silene ciliata, local adaptation, southern border, reciprocal sowing, drought stress, altitude gradient