Nav: Home

A link between greenhouse gases and the evolution of C4 grasses

December 20, 2007

How a changing climate can affect ecosystems is an important and timely question, especially considering the recent global rise in greenhouse gases. Now, in an article published online on December 20th in the journal Current Biology, evolutionary biologists provide strong evidence that changes in global carbon dioxide levels probably had an important influence on the emergence of a specific group of plants, termed C4 grasses, which includes major cereal crops, plants used for biofuels, and species that represent important components of grasslands across the world.

C4 plants are specially equipped to combat an energetically costly process, known as photorespiration, that can occur under conditions of high temperature, drought, high salinity, and--ith relevance to these latest findings--low carbon dioxide levels. Although a combination of any of these factors might have provided the impetus behind the evolution of the various C4 lineages, it had been widely speculated that a drop in global carbon dioxide levels, occurring approximately 30 million years ago during the Oligocene period, may have been the major driving force. Establishing the link between the two, however, has proven difficult partly because there are no known fossils of C4 plants from this period. Enter Pascal-Antoine Christin and colleagues from the University of Lausanne, Switzerland, who decided to take an alternative approach to date a large group of grasses. By using a "molecular clock" technique, the authors were able to determine that the Chloridoideae subfamily of grasses emerged approximately 30 million years ago, right around the time global carbon dioxide levels were dropping. Furthermore, a model of the evolution of these grasses suggests that this correlation is not a trivial coincidence and instead reflects a causal relationship.

As the authors noted in their study, many of the C4 grasses evolved after the drop in global carbon dioxide levels 30 million years ago. How to explain this" The authors speculate that while an atmosphere low in carbon dioxide established the basic conditions necessary for C4 evolution, other ecological factors might be at work. In light of this, the authors hope to apply the same approaches used in the paper described here to investigate the role of other variables, such as drought, salinity, and flooding, in the evolution of C4 plants. In addition to improving our understanding of how climate changes influenced ecosystems in the past, such studies may allow predictions of how human activities could affect the planet in the future. Indeed, with regard to global carbon dioxide levels, Christin and colleagues write, "Besides its influence on climatic variables, increased CO2 concentration could trigger important ecological changes in major terrestrial ecosystems by affecting the distribution of C4-dominated biomes and the affiliated flora and fauna." This implies that a reversal of the conditions that favored C4 plants could potentially lead to their demise--a startling prospect if one considers the human race's reliance on C4 crops like corn, sugarcane, sorghum, and millets.
-end-
The researchers include Pascal-Antoine Christin, Department of Ecology and Evolution, Biophore, University of Lausanne, Switzerland; Guillaume Besnard, Department of Ecology and Evolution, Biophore, University of Lausanne, Switzerland; Emanuela Samaritani, Department of Ecology and Evolution, Biophore, University of Lausanne, Switzerland; Melvin R. Duvall, Department of Biological Sciences, Northern Illinois University, DeKalb, Ill., USA; Trevor R. Hodkinson, Department of Botany, School of Natural Sciences, University of Dublin, Trinity College, Dublin, Ireland; Vincent Savolainen, Imperial College, Berkshire, UK; and Nicolas Salamin, Department of Ecology and Evolution, Biophore, University of Lausanne, Switzerland.

Cell Press

Related Evolution Articles:

Prebiotic evolution: Hairpins help each other out
The evolution of cells and organisms is thought to have been preceded by a phase in which informational molecules like DNA could be replicated selectively.
How to be a winner in the game of evolution
A new study by University of Arizona biologists helps explain why different groups of animals differ dramatically in their number of species, and how this is related to differences in their body forms and ways of life.
The galloping evolution in seahorses
A genome project, comprising six evolutionary biologists from Professor Axel Meyer's research team from Konstanz and researchers from China and Singapore, sequenced and analyzed the genome of the tiger tail seahorse.
Fast evolution affects everyone, everywhere
Rapid evolution of other species happens all around us all the time -- and many of the most extreme examples are associated with human influences.
Landscape evolution and hazards
Landscapes are formed by a combination of uplift and erosion.
New insight into enzyme evolution
How enzymes -- the biological proteins that act as catalysts and help complex reactions occur -- are 'tuned' to work at a particular temperature is described in new research from groups in New Zealand and the UK, including the University of Bristol.
The evolution of Dark-fly
On Nov. 11, 1954, Syuiti Mori turned out the lights on a small group of fruit flies.
A look into the evolution of the eye
A team of researchers, among them a zoologist from the University of Cologne, has succeeded in reconstructing a 160 million year old compound eye of a fossil crustacean found in southeastern France visible.
Is evolution more intelligent than we thought?
Evolution may be more intelligent than we thought, according to a University of Southampton professor.
The evolution of antievolution policies
Organized opposition to the teaching of evolution in public schoolsin the United States began in the 1920s, leading to the famous Scopes Monkey trial.

Related Evolution Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Moving Forward
When the life you've built slips out of your grasp, you're often told it's best to move on. But is that true? Instead of forgetting the past, TED speakers describe how we can move forward with it. Guests include writers Nora McInerny and Suleika Jaouad, and human rights advocate Lindy Lou Isonhood.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...