Figures and supplementary data for The CAM Lineages of Planet Earth (Gilman et al. accepted).
Supplementary-Table-S3.csv: estimations of the fractions of species expected to be capable of CAM in genera known to possess at least one CAM speciesSupplementary-Table-S4.csv: family-level CAM species diversity estimations made by summation of genus-level CAM species diversity statistics inSupplementary-Table-S3.csv
Using the list of CAM genera (Table 1 in Gilman et al. accepted), lists of species from Kew’s Plants of the World Online (POWO)and by placing known CAM and non-CAM species in phylogenetic context, we estimated the number of species capable of CAM on a genus-by-genus basis. Genera with multiple taxa investigated for CAM were binned into all (100%), most (75%), half (50%), some (25%), few (5%), or rare (1%) species estimated to be capable of CAM based on the proportions of CAM and non-CAM taxa reported and their phylogenetic distribution. For example, all species in all genera of Cactaceae and Crassulaceae were considered to use CAM because every species studied thus far has been reported to use CAM to some degree; furthermore, these taxa are well distributed throughout their respective phylogenies. Combining the list of C3 and CAM Peperomia from Holthe et al. (1992) and a recent phylogeny by Frenzke et al. (2016) showed that two major subclades have not been surveyed for CAM, one contained exclusively C3 taxa, one exclusively CAM taxa, and five contained mixed photosynthetic types (including the largest, Micropiper, with ca. 800 species). Given this phylogenetic distribution of photosynthetic types, we estimated that CAM evolved several times in Peperomia and that roughly half of Peperomia species are capable of CAM. We generally did not assume that CAM evolved along a tip branch (except in monotypic genera, e.g., Welwitschia); that is, despite only a single record of CAM, we categorized genera including Jatropha and Pilea as having few CAM species (5%). Finally, to estimate lower and upper bounds on these counts, we moved every genus either down or up a bin, respectively; genera binned as “few” were recategorized as “rare” (1%) when estimating lower bounds and genera binned as “all” were not altered when estimating upper bounds. The upper bounds on Australian Calandrinia (also known as Parakeelya or Rumicastrum) and Clusia were reduced to 95% (rather than 100%), because multiple taxa have been demonstrated to not express detectable CAM (Hancock et al., 2019; Pachon et al., 2022). Finally, in clades where records of CAM are widely distributed but sampling is sparse, which may imply a single more ancient origin of CAM, the upper bound increased (e.g., within the Hydnophytineae clade of Rubiaceae).
Note that these numbers represent the first attempt at estimating CAM species diversity in a systematic way. These numbers should be treated with caution proportional to degree each clade has been investigated. We hope to improve the accuracy and precision of these data with community input!
- Frenzke L, Goetghebeur P, Neinhuis C, Samain M-S, Wanke S. 2016. Evolution of epiphytism and fruit traits act unevenly on the diversification of the species-rich genus Peperomia (Piperaceae). Frontiers in Plant Science 7: 1145.
- Hancock LP, Holtum JAM, Edwards EJ. 2019. The evolution of CAM photosynthesis in Australian Calandrinia reveals lability in C3+CAM phenotypes and a possible constraint to the evolution of strong CAM. Integrative and Comparative Biology 59: 517–534.
- Holthe PA, Patel A, Ting IP. 1992. The occurrence of CAM in Peperomia. Selbyana 13: 77–87.
- Gilman IS, Smith JAC, Holtum JAM, Sage RF, Silvera K, Winter K, Edwards EJ. Accepted. The CAM lineages of planet earth. Annals of Botany.
- Pachon P, Winter K, Lasso E. 2022. Updating the occurrence of crassulacean acid metabolism (CAM) in the genus Clusia through carbon isotope analysis of species from Colombia. Photosynthetica 60: 304‒322.