Archive for November, 2011

MEDECOS XII (2011): fire and evolution

November 26th, 2011 No comments

Mediterranean Ecosystem (MEDECOS) conferences are held every 3–5 yrs, rotating venues through all five Mediterranean-type climate (MTC) regions of the world. The first meeting was held in Valdivia (Chile) in 1971. The last MEDECOS was held in Los Angeles (University of California, September 6-9, 2011, [1]), and about 300 scientist from the different MTC regions got together and presented their research on the different aspects of the ecology in mediterranean ecosystems. In this MEDECOS, fire was an important topic, it was explicit in the title at least in the following 5 special sessions:

Fire as an evolutionary pressure shaping plant traits (6th Sept, Pausas & Schwilk)
– Fire management at the wildland-urban interface (7th Sept, Keeley)
– Global change and fire (7th Sept, van Mantgem)
– Fire ecology in Mediterranean woodlands ans shrublands (8th Sept, O’Leary)
– Fire management (9th Sept, Fotheringham)

Dylan Schwilk and I organised the first one which highlighted several key aspects on the role of fire in plant evolution: First, there is good evidence for vegetation-fire regime feedbacks at different spatial and temporal scales, in such a way that plant flammability is a major driver of plant evolution and vegetation distribution. Second, the evidence that fire acts as a selective force is apparent on both micro- and macro-evolutionary scales, suggesting that fire shapes plant traits and generates fire adaptations. And third, that fire is a complex selective pressure – plants adapt to (and, in turn, influence) particular fire regimes rather than fire in the abstract. This is an exciting time for fire ecologists, as fire is now recognized as fundamental for many ecological and evolutionary processes; the coming macro- and micro- evolutionary studies will certainly reinforce many of the ideas drawn during the meeting [2]. The details of this session, including slides of the talks and a summary of the session [2], are now available here .

[1 ] MEDECOS 2011:  web | program | abstracts | final resolution

[2] Pausas, J. G. and D. W. Schwilk. 2012. Fire and plant evolution. New Phytologist 193 (2). [doi | pdf]

Ulex born to burn

November 9th, 2011 No comments

Recurrent fires are a strong evolutionary pressure shaping plants [1,2]. It has been hypothesized that in fire prone-ecosystems, natural selection has favoured the development of traits that enhance flammability [3]. Consistent with this idea, in a recent study [4] we found that Ulex parviflorus (Fabaceae) populations that inhabit in recurrently burn areas (HiFi populations) are more flammable than populations of this species growing in old-fields where the recruitment was independent of fire (NoFi populations). That is, HiFi plants ignite quicker, burn slower, release more heat and have higher bulk density than NoFi plants. Thus, it appears that repeated fires select for individuals with higher flammability, and thus driving trait divergence among populations living in different fire regimes. These results provide some field support for the ‘kill thy neighbour’ hypothesis [3], but they also highlighted the need for heritability studies to unambiguously demonstrate natural selection driven by fire. This study together with other studies recently commented in this blog [5, 6] are placing flammability as a fundamental trait in plant evolution.

Figure: Flammability experiments using an epiradiator [4].


[1] 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 Science 16:406-411. [doi | pdf]

[2] Pausas J.G. & Keeley J.E. 2009. A burning story: The role of fire in the history of life. BioScience [doi | jstore | pdf]

[3] Bond, W. J. and J. J. Midgley. 1995. Kill thy neighbour: an individualistic argument for the evolution of flammability. Oikos 73:79-85.

[4] Pausas J.G., Alessio G., Moreira B., Corcobado G. 2012. Fires enhance flammability in Ulex parviflorus. New Phytologist 193:18-23 [doi | pdf]

[4′] Pausas J.G. & Moreira B. 2012. Flammability as a biological concept. New Phytologist 194: 610-613. [doipdf]

[5] Pausas JG. 2011. Australia born-to-burn: a phylogenetic approach., 18/March/2011 [link]

[6] Pausas JG. 2011. Fire and evolution: Cretaceous fires and the spread of angiosperms., 9/Sept/2011 [link]