In a study published in the journal Current Biology, an international research team that included scientists from the department of chemical and physical sciences at UTM, has found an explanation for why large organisms evolved. Researchers have shown that the oldest known eukaryotes survived simply by outgrowing their competitors.
The study focused on rangeomorphs, fractal-patterned multicellular organisms that grew from the sea floor 580 million years ago which are the earliest known example of multicellular life. Rangeomorphs grew out of reach of sunlight and got their energy by taking up nutrients through osmosis, a process whose efficiency depends on the flow rate of water around an organism. Using rangeomorph fossils and a method called canopy flow analysis, scientists were able to model how water currents interacted with the dense rangeomorph communities that had grown on the sea floor, and, for the first time, to explain how rangeomorphs could effectively compete with their prokaryotic neighbours.
Single-celled prokaryotes can increase their ability to absorb nutrients by moving to increase the flow around them and by assuming long filamentous shapes. On the other hand, rangeomorphs increased flow across their surfaces by growing in tall, dense communities. Taller rangeomorph communities had access to higher flow and could absorb nutrients more quickly. This size advantage suggests that rangeomorphs were an important stepping stone towards the evolution of large motile multicellular organisms.
