Tracing evolution of photosynthetic pathways

This study examines the evolution of photosynthesis from C3 to C4 pathway and sheds light on the ecology of intermediate species

Data resources used via GBIF : 20,373 species occurrences
White wallrocket (Diplotaxis erucoides)

White wallrocket (Diplotaxis erucoides), a C3-C4 intermediate species of the Brassicaceae family. Photo by Xavier Ma Ma licensed under CC BY-NC 4.0.

Photosynthesis in flowering plants relies on two different biochemical pathways known as C3 and C4. C4 photosynthesis evolved from C3, particularly in warm regions where it boosts growth, and today, intermediate species with traits from both C3 and C4 pathways exist, though little is known about their ecology.

In this paper, researchers use GBIF-mediated occurrences combined with data on climate and soil conditions to study the distribution and phylogeny of 56 such C3- C4 intermediate species. They report that the group occurs across tropical and temperate regions, spanning a belt from 50°S to 65°N, and at elevations ranging from below sea level to the Andes mountains. Climates supporting C3- C4 intermediates feature temperatures from below zero to 30°C, and precipitation ranging from being virtually absent to extremely wet.

Precipitation and soil preferences tended to correlate with those of C3 close relatives, however, intermediate taxa inhabit warmer climates, suggesting that the condition may facilitate evolution of the full C4 pathway.

Citations

Lundgren MR and Christin P-A (2016) Despite phylogenetic effects, C3–C4 lineages bridge the ecological gap to C4 photosynthesis. Journal of Experimental Botany. Oxford University Press (OUP) 68(2): 241–254. Available at: https://doi.org/10.1093/jxb/erw451.

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