bout 510 million years ago, life thrived in Earth’s oceans and freshwater lakes, writes John McPhee in the (Nova Scotia) Chronicle Herald. The ancient ancestors of sea urchins, starfish and jellyfish abounded, as did plants such as red and green algae.
There was life on land as well but in much more subtle forms. While recent research indicates crustacean-like animals were beginning to explore dry ground, the closest thing to a plant was a lichen-like green ground cover.
“It was a pretty bleak place,” said biochemist Jan de Vries, a post-doctoral fellow at Dalhousie University, in Nova Scotia, Canada.
All that would change within the next 60 million years when photosynthetic plants including trees spread over the Earth’s surface, taking their energy from the sun and expelling the oxygen that would help give rise to the Cambrian explosion of animal life.
The turning point in the spread of plants and animals from the water to land can be traced to a plant called streptophyte algae. “The entire terrestrial macrobiome that is photosynthetic, that is land plants, traces back to a single terrestrialization event,” Dr. de Vries explained in a recent interview at his lab at the Comparative Geonomics & Evolutionary Informatics Centre at Dalhousie. “So it’s a particular lineage of these groups of algae that grows above their substrate and…conquered land on a global scale.”
Dr. De Vries, recently finished a research project that used genetic sequencing to provide a clearer picture of exactly what characteristics this modest algae had that sparked such a momentous transition in the development of life on our planet.
He determined the genetic changes that allowed the algae to adapt to terrestrial life through a process called molecular phylogenetics. This involved exposing lab-grown algae samples to conditions that the plant would have experienced on land, such as strong light and fluctuating temperatures. He also grew a “control” set of samples that wasn’t exposed to these conditions. All of the samples were sent off to a Quebec lab that sequenced the genetic information.
“You can extract genetic information from an organism pretty quickly and also in a pretty cost-efficient manner that was not believed to be possible just 10 years ago,” said the native of Dusseldorf, Germany, who moved to Canada in September 2016 to work with Dalhousie biochemist and molecular biologist John Archibald.
Dr. De Vries’ paper, which was funded by the German Research Foundation, was published last week in the National Academy of Sciences of the United States journal. Besides painting a clearer picture of early plant evolution, he said practical applications could include genetic manipulation of modern-day plants to help them survive changing environmental conditions.