Scientists discovered the earliest known evidence of reproduction among complex organisms, and the findings could shed light on the origins of the marine environment we see today.
A recent study found 565 million-year-old organisms known as rangeomorphs reproduced using a "two-step" method, the University of Cambridge reported. The ancient organisms would send out an "advance party" to settle in new territory, and then rapidly colonize the new neighborhood.
To make their findings, a team of researchers used statistical techniques to assess the distribution of populations of the rangeomorph Fractofusus. This method revealed that larger "grandfather" rangeomorphs were randomly distributed throughout the environment, and surrounded by smaller "parents" and "children." This pattern closely resembles the reproduction of modern-day plants, and suggests a similar two-step method. In this reproduction technique, the "grandparents" are driven by waterborne propagules, while the "parents" and "children" were grown from scouts sent out by the older generation.
These findings are particularly fascinating because it has been a long-standing mystery as to whether rangeomorphs were closer to plants or animals. These creatures had no mouths or limbs that allowed them to move, and most likely absorbed nutrients through the water around them.
"Rangeomorphs don't look like anything else in the fossil record, which is why they're such a mystery," said Emily Mitchell, a postdoctoral researcher in Cambridge's Department of Earth Sciences, and the paper's lead author. "But we've developed a whole new way of looking at them, which has helped us understand them a lot better - most interestingly, how they reproduced."
The reproduction model observed in the rangeomorphs closely resembled the nested double Thomas cluster model seen in modern day plants, which consists of asexual reproduction by means of stolons or runners.
"Reproduction in this way made rangeomorphs highly successful, since they could both colonise new areas and rapidly spread once they got there," Mitchell said. "The capacity of these organisms to switch between two distinct modes of reproduction shows just how sophisticated their underlying biology was, which is remarkable at a point in time when most other forms of life were incredibly simple."
The findings were published in a recent edition of the journal Nature.
