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Intraspecific plant variability and the spatial scale

September 24th, 2011 Leave a comment Go to comments

Variability is a fundamental characteristic of life and the raw material for natural selection, driving speciation and diversification processes. Traditional biogeographical theory would predict that plants in populations that are close each other (e.g., few km) should be more similar among them, than plants in distant populations (e.g., 100s or 1000s km). This is because biogeographical processes such as migration, glacial/interglacial climatic fluctuations and isolation should cause distant plant populations to diverge, and thus enhance intraspecific variability at large scales, while gene flow through close populations should reduce divergences. In contrast, in a recent paper we suggest that in fire prone-ecosystems, where fire may generate local heterogeneity, local variability in traits related to regeneration are quite large, overriding the variability at the larger scale [1]. Studying post-fire regeneration traits in Cistus salviifolius and Lavandula stoechas, in eastern Iberia (IB, Spain) and in south-western Anatolia (AN, Turkey), we found that the trait variability within each region is larger than between regions (separated by about 2600 km, with the sea in the middle). The traits studied were seed size, seed dormancy and germination stimulation by head and by smoke. The two studied species exhibited germination stimulated by the fire-related cues; and independently of the region, the different populations of each species had a similar pattern of response. That is, Cistus salviifolius was stimulated by heat and Lavandula stoechas was mainly stimulated by smoke, although heat also exhibited a positive effect on the latter species (see also [2] for more details on heat- and smoke- stimulated germination). All these results supports the prominent role of fire as an ecological and evolutionary process across the Mediterranean Basin, producing trait variability and shaping biodiversity [3, 4].

References

[1] Moreira B., Tavsanoglu Ç., Pausas J.G. 2012. Local vs regional intraspecific variability in regeneration traits. Oecologia 168: 671-677 [doi | pdf]

[2] Moreira B., Tormo J., Estrelles E., Pausas J.G. 2010. Disentangling the role of heat and smoke as germination cues in Mediterranean Basin flora. Annals of Botany 105: 627-635.[pdf| doiblog]

[3] Pausas J.G. & Keeley J.E. 2009. A burning story: The role of fire in the history of life. BioScience 59: 593-601 [doi | pdfpost]

[4] Keeley J.E., Pausas J.G., Rundel P.W., Bond W.J., Bradstock R.A. 2011. Fire as an evolutionary pressure shaping plant traits. Trends in Plant Science 16(8): 406-411. [doi | pdf | For managers]

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