Before Predation, the Sex Was Great

There's a neat study being published today in Science discussing the reproductive potential of ecological systems 570 mya. The findings are based on the new discovery of a "tube-like" organism (so say the PRs) called Funisia dorothea, which apparently was able to reproduce sexually and lived in a complex ecosystem despite the apparent absence of predation. The researchers have taken this to be an example of a much more complex world during the Neoproterozoic and periods before. From the PR:

...in describing the ecology and reproductive strategies of Funisia dorothea, a tubular organism preserved as a fossil, the researchers found that the organism had multiple means of growing and propagating -- similar to strategies used by most invertebrate organisms for propagation today...

"How Funisia appears in the fossils clearly shows that ecosystems were complex very early in the history of animals on Earth -- that is, before organisms developed skeletons and before the advent of widespread predation," said Droser, who was joined in the research by James G. Gehling of the South Australia Museum.

Droser and Gehling observed that Funisia appears as 30 cm-long tubes in the fossils. They also observed that the tubes commonly occur in closely-packed groups of five to fifteen individuals, displaying a pattern of propagation that often accompanies animal sexual reproduction.

"In general, individuals of an organism grow close to each other, in part, to ensure reproductive success," said Droser, the first author of the research paper and the chair of the Department of Earth Sciences. "In Funisia, we are very likely seeing sexual reproduction in Earth's early ecosystem -- possibly the very first instance of sexual reproduction in animals on our planet."

According to Droser and Gehling, the clusters of similarly sized individuals of Funisia are strongly suggestive of "spats," huge numbers of offspring an organism gives birth to at once. Besides producing spats, the individual tubular organisms reproduced by budding, and grew by adding bits to their tips.

"Among living organisms, spat production results almost always from sexual reproduction and only very rarely from asexual reproduction," Droser said.