A research team from Lund University in Sweden has studied green algae in Swedish lakes, identifying environmental conditions that support multicellularity and providing new insights into the evolutionary pathways of life. The findings challenge the belief that multicellularity evolved for natural advantages, such as protection from predators. Instead, multicellularity arises as a byproduct of unicellular organisms’ strategy to reduce environmental stress.

The study highlights that there are no benefits or costs to living in multicellular groups, and the findings contribute to our understanding of the origins of biodiversity and how an important group of species, green algae, proliferate and survive in different environmental conditions.

The evolution of multicellular life played a key role in the creation of biodiversity. However, until now we knew surprisingly little about the natural environmental conditions that favor the formation of multicellular groups.

Cooperation between the cells of multicellular organisms enabled the development of eyes, wings, and leaves. The dominant explanation for why multicellularity evolved is that being in a group allows the species to better cope with environmental challenges; here being in a large group can protect cells from being eaten for example.

“Our results challenge this idea by showing that multicellular groups do not form because they are naturally beneficial, but rather as a byproduct of single-cell strategies to reduce environmental stress. “Cells in particular have a team to protect themselves from the environment,” said Lund University biologist Charlie Cornwallis. “They produce substances that appear to prevent daughter cells from dispersing from their parent cells,” he says.

To understand how and why unicellular organisms evolved into multicellular organisms, scientists experimented on green algae, where some species were always unicellular, some were unicellular but under certain conditions became multicellular, and others were multicellular, always containing thousands of cells. They did. . They can then identify the environmental conditions that support multicellularity and understand the benefits and costs for organisms. The researchers then combined the data with information about the environments to which single-celled and multicellular green algae in Sweden have adapted.

“I’m surprised that there are no benefits or costs to living in multicellular groups. The conditions in which individual cells live can be very different when they swim on their own, become trapped in other cells and need to engage in coordinated activities. Imagine being physically attached to your family members, this would have a significant impact on you. I think,” says Charlie Cornwallis.

The study, conducted in Swedish lakes, not only provides information about where and why green algae occur, but also helps us understand the origins of the biodiversity that shapes the world around us.

“The results of this study add to our understanding of how complex life evolved on Earth. They also provide insight into how an important group of species, such as the green algae that produces fuel for ecosystems, can reproduce and survive in different environmental conditions. Once on the shore of a nitrogen-rich lake.” As you walk, imagine helping the evolution of multicellular life,” says Charlie Cornwallis.