Evolution of hydrological niches in Restionaceae: a project update

Araya, Y. N.; Silvertown, J.; Linder, H. P; Gowing, D. J.; Midgley, G. F. and McConway, K. J. (2008). Evolution of hydrological niches in Restionaceae: a project update. In: Mucina, L.; Kalwij, J. M.; Smith, V. R.; Chytry, M.; White, P. S.; Cilliers, S. S.; Pillar, V. D.; Zobel, M. and Sun, I-Fang eds. Frontiers of Vegetation Science - An evolutionary angle. Somerset West: Keith Phillips Images, pp. 15–16.

URL: http://www.sci.muni.cz/botany/chytry/Mucina_etal20...


Plants are in general exquisitely sensitive to differences in soil moisture availability, particularly when competing with each other. We have previously found that species segregate along soil moisture gradients in English wet meadows (Silvertown et al. 1999) and we now have good evidence from several sites in the Western Cape that the same phenomenon occurs in fynbos communities. Our discovery of plants segregating into hydrological niches, defined by their location along soil moisture gradients, in phylogenetically completely different communities in the northern and southern hemispheres suggests that this form of niche separation is very general indeed.

We are now using the Restionaceae family, one of the key components of fynbos vegetation, to test the hypothesis that the radiation of the Restionaceae clade in the Cape involved the occupation of novel niches in hydrological niche space. We have so far collected hydrological data on 39 species of Restionaceae from 6 sites and have a species-level phylogeny of the family (Hardy et al. 2008) which enables us to estimate the rate of evolutionary change in hydrological niche parameters during the radiation of the group.

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