For the first time in over a billion years, two lifeforms have merged into a single organism. This rare event, known as primary endosymbiosis, has previously occurred only twice in Earth’s history. The initial occurrence led to the development of complex life through the creation of mitochondria, and the second event led to the emergence of plant life.
A global team of researchers has recently observed this evolutionary milestone involving a common oceanic algae species and a bacterium.
“The first time we think it happened, it gave rise to all complex life,” said Tyler Coale, a postdoctoral researcher at the University of California, Santa Cruz, who led the research on one of two recent studies that uncovered the phenomenon.
“Everything more complicated than a bacterial cell owes its existence to that event. A billion years ago or so, it happened again with the chloroplast, and that gave us plants.”
Symbiotic evolution: Algae consumes bacterium to gain new abilities
The process entails the algae engulfing the bacterium and providing it with the necessary nutrients, energy, and shelter in exchange for capabilities that algae previously lacked, specifically the ability to fix nitrogen from the atmosphere.
The algae then incorporate the bacterium as an internal organ called an organelle, which becomes vital to the host’s ability to function.
The discovery, made by researchers from both the US and Japan, is expected to reshape our understanding of evolutionary biology and could revolutionize agricultural practices.
“This system is a new perspective on nitrogen fixation, and it might provide clues into how such an organelle could be engineered into crop plants,” said Dr Coale.
The research findings have been documented in the prestigious journals Science and Cell.
Contributors to this groundbreaking research included scientists from the Massachusetts Institute of Technology (MIT), the University of Rhode Island, the University of California, San Francisco, UC Santa Cruz, the Lawrence Berkeley National Laboratory, the Institut de Ciències del Mar in Barcelona, National Taiwan Ocean University, and Kochi University in Japan.