Talks & media

01. Gilman IS, Edwards EJ. 2018. Distinguishing CAM photosynthesis with machine learning. Botany Conference. Rochester, WI

Abstract: Crassulacean Acid Metabolism (CAM) has evolved at least 35 times independently throughout the plant kingdom—in lineages as distantly related as Isoetes and orchids. Although we recognize many, repeated origins of other modifications to the standard C3 pathway, such as C4 photosynthesis, CAM has evolved in an extremely diverse set of ecological circumstances and in a variety of types. CAM is suspected to have played a role in the massive diversification of tropical lineages, such as the bromeliads and orchids, but also in some of the most arid-loving lineages like the Portulacinae (Carophyllales) and Euphorbiaceae. Furthermore, the types of CAM (full CAM, constant high levels of carbon fixation strictly at night; low level CAM, constant low levels of carbon fixation both during the day and night; and facultative CAM, low to high levels of carbon fixation at night in the present of a stressor such as drought) do not appear to represent a continuum of transitional states on the path to full CAM. Rather, these types may represent stable phenotypes that have evolved for different, but not unrelated, reasons. Disentangling and distinguishing the types of CAM and the problems that they solve in disparate lineages and ecologies therefore precludes a full understanding of the evolution of CAM photosynthesis. Here, we show how machine learning techniques can be used to distinguish and place boundaries on different types of CAM.