Photosynthetic innovation broadens the niche within a single species

Lundgren, Marjorie R. and Besnard, Guillaume and Ripley, Brad S. and Lehmann, Caroline E. R. and Chatelet, David S. and Kynast, Ralf G. and Namaganda, Mary and Vorontsova, Maria S. and Hall, Russell C. and Elia, John and Osborne, Colin P. and Christin, Pascal-Antoine (2015) Photosynthetic innovation broadens the niche within a single species. Ecology Letters, 18 (10). pp. 1021-1029. ISSN 1461-023X

Abstract

Adaptation to changing environments often requires novel traits, but how such traits directly affect the ecological niche remains poorly understood. Multiple plant lineages have evolved C-4 photosynthesis, a combination of anatomical and biochemical novelties predicted to increase productivity in warm and arid conditions. Here, we infer the dispersal history across geographical and environmental space in the only known species with both C-4 and non-C-4 genotypes, the grass Alloteropsis semialata. While non-C-4 individuals remained confined to a limited geographic area and restricted ecological conditions, C-4 individuals dispersed across three continents and into an expanded range of environments, encompassing the ancestral one. This first intraspecific investigation of C-4 evolutionary ecology shows that, in otherwise similar plants, C-4 photosynthesis does not shift the ecological niche, but broadens it, allowing dispersal into diverse conditions and over long distances. Over macroevolutionary timescales, this immediate effect can be blurred by subsequent specialisation towards more extreme niches.