Reuniting biogeochemistry with ecology and evolution
Biodiversity conservation strategies that adapt to ongoing environmental changes require the ability to predict global biogeographical patterns (1). Research on macroecology—the study of relationships between organisms and their environment at large spatial scales—reports a pressing need for new information on freshwater species, which show exceptionally high declines and extinction rates worldwide (2, 3). The anticipation of changes in the distribution and community composition of freshwater organisms has forced scientists to grapple with a complex puzzle of interwoven ecological and evolutionary processes, including the ability of autotrophic organisms to convert different sources of inorganic carbon to organic compounds (carbon fixation). On page 878 of this issue, Iversen et al. (4) report on a pioneering global analysis of a key functional trait in freshwater plants—the ability to use bicarbonate for photosynthesis—as a function of geochemical properties of water catchments.
| By Rafael Marcé, et al. |
Nov 15th, 2019 |
Catchment properties and the photosynthetic trait composition of freshwater plant communities
Freshwater plants can be broadly divided into two major categories according to their photosynthetic traits: Some use carbon dioxide as their carbon source, whereas others use bicarbonate. Iversen et al. found that the relative concentrations of these two inorganic carbon forms in water determine the functional composition of plant communities across freshwater ecosystems (see the Perspective by Marcé and Obrador). They created global maps revealing that community composition is structured by catchment geology and not climate (in contrast to the terrestrial realm, where the trait composition is structured by temperature and rainfall). Anthropogenic influences from land-use change are causing large-scale increases in bicarbonate concentrations in freshwater catchments and are thus leading to wholesale changes in the composition of their aquatic plant communities.
| By L. L. Iversen, et al. |
Nov 15th, 2019 |
