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Fire generates intraspecific trait variability in neotropical savannas

August 28th, 2012 No comments

“Cerrado” are neotropical savannas from Brazil. As in most savannas, fire is very frequent in cerrado, and fires has been occurring in these ecosystems during the last few millions years. Consequently, cerrado communities are strongly filtered by fire and are composed by species capable of succeed under frequent fires (e.g., resprouters, with very thick bark, etc). A recent study [1] comparing zones with different fire regimes (annual fires, biennial fires, and protected from fires) within the cerrado (in Emas National Park) suggests that most plant trait variability is found within species (intraspecific) and little trait variability is due to changes in species composition (interspecific) between fire regimes. Thus, at community scale, fire act more as an filter, preventing some of the species from outside cerrado to colonize the cerrado (e.g., from nearby non-flammable forests), than as an internal factor structuring species composition in the already filtered cerrado communities with different fire regimes. However, fire acts as an important factor generating intraspecific variability. These results support the hypothesis of the prominent importance of intraspecific variability in strongly fire-filtered communities [2,3].

Figure: The rhea (emas in Portuguese; Rhea americana) are a flightless birds that give the name to the Emas National Park (Parque Nacional das Emas), a World Natural Heritage site located in the Brazilian Central Plateau (Photo: JG Pausas, 2009, during the field sampling [1]).

References

[1] Dantas V.L., Pausas J.G., Batalha M.A., Loiola P.P. & Cianciaruso M.V. 2013. The role of fire in structuring trait variability in Neotropical savannas. Oecologia, 171: 487-494. [doi | pdf]

[2] Moreira B., Tavsanoglu Ç. & Pausas J.G. 2012. Local versus regional intraspecific variability in regeneration traits. Oecologia, 168, 671-677. [doi | pdf | post]

[3] Pausas J.G., Alessio G., Moreira B. & Corcobado G. 2012. Fires enhance flammability in Ulex parviflorusNew Phytologist 193: 18-23. [doi | wiley | pdf]

 

Fire and the evolution of pine life histories

August 15th, 2012 No comments

Many pines species are fire adapted. In 1998, JE Keeley & PH Zedler provided a seminal paper showing the various fire adaptations of pines, and the relation between the different adaptations and the different fire regimes [1]. Recent phylogenetic [2,3] and conceptual [4,5] advances in fire ecology have allowed to better understand the evolutionary role of fire in plants, and specifically in pines [2-6]. In a recent paper, JE Keeley provides a new review on the ecology and evolution of pine life histories [7]. Pinus originated ~150 Ma in the mid-Mesozoic Era and radiated across the northern continent of Laurasia during the Cretaceous period, when fire activity was high [3]. Pines have followed two evolutionary strategies interpreted as responses to competition by the newly emerging angiosperms: 1) The Strobus lineage mostly has radiated into stressful sites of low nutrient soils and extremes in cold or heat; ans 2) The Pinus (subgenus) lineage has radiated into fire-prone landscapes with diverse fire regimes. Based on the life history traits associated to fire, JE Keeley define four pine syndromes [7]: fire-avoiders (no fire-adapted; with thin bark), fire-toleraters (adapted to surface fires; with thick bark and self-pruning of dead branches; tall pines), fire-embracers (adapted to crown fires; with retention of dead branches and serotinous cones), and fire-refugia (with marked metapopulation dynamics) strategies.

Figure: Basal fire scar (a) and cross-section of pine with previous fires delineated (b) demonstrating fire survival after recurrent fires. Photos by JE Keeley from [7].

References
[1] Keeley J.E. & Zedler P.H. 1998. Evolution of life histories in Pinus. In: Ecology and biogeography of Pinus (ed. Richardson DM). Cambridge University Press Cambridge (UK), pp. 219-250.

[2] Schwilk D.W. & Ackerly D.D. 2001. Flammability and serotiny as strategies: correlated evolution in pines. Oikos, 94, 326-336. [doi]

[3] He T., Pausas J.G., Belcher C.M., Schwilk D.W. & Lamont B.B. 2012. Fire-adapted traits of Pinus arose in the fiery Cretaceous. New Phytol., 194, 751-759. [doi | wiley | pdf ]

[4] Pausas, J. G. and J. E. Keeley. 2009. A burning story: The role of fire in the history of life. Bioscience 59: 593-601. [doi | jstor | pdf]

[5] Keeley, J. E., J. G. Pausas, P. W. Rundel, W. J. Bond, and R. A. Bradstock. 2011. Fire as an evolutionary pressure shaping plant traits. Trends in Plant Sci. 16:406-411.  [doi | pdf]

[6] Pausas J.G. & Schwilk D.W. 2012. Fire and plant evolution. New Phytol., 193, 301-303.  [doi | wiley | pdf]

[7] Keeley J.E. 2012. Ecology and evolution of pine life histories. Ann. For. Sci., 69, 445–453. [doi]

 

Linguistic diversity hotspots

August 2nd, 2012 No comments

Languages can be study using similar tools as we use for biological organism, because languages, like species, have their geographic distribution, they have variability, they evolve with time, they show divergence and extinction processes. In fact there are phylogenetic trees and networks of languages [1] similar to those we build for understanding species evolution. In addition, a recent paper show that the hotspots of species diversity also co-occur with hotspots of language diversity [2], in such a way that highly biodiverse areas accounting for 24% of Earth’s land surface contain ca. 70% of the world’s languages. However, the reasons of this link is not yet well understood. Are the factors that generate linguistic diversity the same to those that generate biodiversity? Is the linguistic diversity a consequence of the biodiveristy? Nearly 60 percent of the languages in high biodiversity regions, like Amazonia and the lowland forests of West Africa, are spoken by fewer than 10,000 people; more than 1,200 of those languages are spoken by fewer than 1,000 people. So cultural diversity, as biological diversity, is threatened. It is worth mentioning the recent online collaborative effort trying to preserve samples of endangared languages [3].


Geographic distribution of indigenous languages (from [2])

References
[1] Diversity of languages, jgpausas.blogs.uv.es, November 7th, 2010.

[2] Gorenflo L.J., Romaine S., Mittermeier R.A. & Walker-Painemilla K. (2012). Co-occurrence of linguistic and biological diversity in biodiversity hotspots and high biodiversity wilderness areas. PNAS [doi]

[3] Endangered Languages, A project by the Alliance for Linguistic Diversity, www.endangeredlanguages.com

 

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