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Archive for November, 2010

Fire and alien plants

November 25th, 2010 No comments

In Mediterranean Basin ecosystems, fires are frequent, and post-fire regeneration is tipically based on native species, that is, there is no invasion of alien species after fire. However, this is not the case in the other Mediterranean climatic regions, where fire frequencies higher than their natural (historic) fire regime favors the invasion of alien plants. This is specially the case in the Mediterranean ecosystems of Chile, where recurrent fires play a little role on the evolutionary history. In Chile, fires appeared with the indigenous settlements, and increased exponentially since the time of the Spanish invasion (1536). This increase in fires, together with heavy grazing, has reduced the native matorral and increased the invasive species. In a recent paper, Gómez-Gonzalez et al. [1] show that fire open the window for the establishment of annual plants, and most of them are alien (from the Mediterranean Basin). The successful establishment of alien annuals was due to their ability to maintain rich seedbanks in burned areas and to the greater propagule arrival compared to native species (annuals or perennials). Thus the results demonstrate that fire is a relevant factor for the maintenance of alien-dominated grasslands in the Chilean matorral and highlight the importance of considering the interactive effect of seed rain and seedbank survival to understand plant invasions patterns in fire-prone ecosystems.

[1] Gómez-González S, Torres-Díaz C., Valencia G, Torres-Morales P, Cavieres L.A., and Pausas J.G (in press). Anthropogenic fires increase alien and native annual species in the Chilean coastal matorral. Diversity and Distributions 17: 58-67 [doi | pdf]

invasion-fumaria_sm
Figure: Chilean matorral recently burnt showing the invasion of Fumaria capreolata (flowering), and annual alien species original from Europe (Foto by S. Gómez-González).

Diversity of languages

November 7th, 2010 No comments

Linguistic diversity has many commonalities with species diversity, and the two disciplines are sharing methodologies. Few years ago, Gray and Atkinson (2003) showed a phylogenetic tree of Ind-European languages [1, see tree], a tree similar to those used in evolutionary biology. This is because languages contain a lot of historic information, like species. In this line, an interesting and recently compilation of papers show the state-of-the-art of evolutionary approaches to study cultural and linguistic diversity [2]. For instance, we can see a phylogeneitc network of the Indo-European languages (see below, by Gray et al.) or the extinction trends of a language (e.g., the case of Gaelic in Scotland, by Kandle et al. [see figure]).

Jarret Diamond recently highlighted the benefits of learning several languages [3]. Apart for the obvious social benefits, there are also health benefits of multilingualism like protection against Alzheimer’s dementia in old people [4]. What it is unclear is whether the health benefits increase with the phylogenetic distance of the languages learned, or not. … So there is still a lot of room for including evolutionary approaches in social and medical sciences.

References:

[1] Gray RD and Atkinson QD 2003. Language-tree divergence times support the Anatolian theory of Indo-European origin. Nature 426: 435-439 (27 Nov. 2003).

[2] Steele J, Jordan P and Cochrane E (eds). 2010. Cultural and linguistic diversity: evolutionary approaches. Phil. Trans. R. Soc. B vol. 365 (no. 1559) [table of contents]

[3] Diamond J. 2010. The Benefits of Multilingualism. Science 330: 332-333 (15 Oct. 2010).

[4] Bialystok E, Craik FI, Freedman M. 2007. Bilingualism as a protection against the onset of symptoms of dementia. Neuropsychologia 45: 459-64

Language-network
NeighborNet analyses of the Indo-European lexical data. Scale bar, 0.1. (Grey et al. 2010, Phil. Trans. R. Soc. B 365: 3923-3933).

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