Nav: Home

Chinese and American scientists review early evolution of eukaryotic multicellularity

January 28, 2015

The ascent of multi-celled life or multicellularity is a major evolutionary transition. Multicellularity evolved independently at least 25 times among eukaryotes, and complex multicellularity (characterized by intercellular communication and tissue differentiation controlled by regulatory gene networks) occurs in a handful of eukaryotic groups including animals.

The repeated evolution of multicellularity implies significant adaptational advantages of being multicellular, but the evolutionary steps toward complex multicellularity have not been completely understood, particularly from the paleontological perspective.

Preserved fossils from approximately 600-million-year-old rocks of the Doushantuo Formation in the Weng'an area of South China offer an opportunity to study the evolution of complex multicellularity in the fossil record. In a new study presented in the Beijing-based journal National Science Review, Virginia Tech geobiologist Shuhai Xiao and his co-authors review fossils from the Weng'an biota help to illuminate the evolutionary transition into complex multicellularity in several eukaryote groups, including red algae and animals.

Modern red algae are aquatic and photosynthetic organisms, mostly marine seaweeds. The majority of modern red algae are multicellular with cell differentiation, thus reaching the evolutionary grade of complex multicellularity.

Some form a thin sheet of tissue, as in Porphyra, which is used today in wrapping sushi. Others have calcified cell walls, as in coralline red algae, which live in coral reefs and contribute to reef construction in important ways.

Red algae from the Weng'an biota show evidence of cellular, tissue, and reproductive differentiation, and some are remarkably similar to modern coralline red algae. Unlike modern coralline red algae, however, those from the Weng'an biota are not calcified. Thus, they probably represent close evolutionary relatives of modern coralline red algae and they predate the rise of biomineralization in the corallines.

The Weng'an biota is best known for its animal embryo-like fossils. These fossils look similar to blastulas, which are animal embryos of an early developmental stage. Like modern animal embryos, the Weng'an blastula-like fossils show evidence of rapid cell divisions with little growth in between. However, because the adult animals of these Weng'an embryos have been elusive, these fossils have also been interpreted as bacteria, unicellular protists, or algae.

To test these different hypotheses, Xiao and his collaborators have been searching for more advanced developmental stages of these Weng'an fossils. Their new discoveries suggest that these blastula-like fossils are clearly multicellular. They likely had adhesion proteins to hold their cells together; they had specialized reproductive cells that are distinct from somatic cells; and they probably had programmed cell death, while their cells lacked a rigid cell wall.

The combination of these features, according to the authors, can rule out bacterial and protist interpretations of the fossils.

Professor Xiao, along with co-authors Xunlai Yuan and Chuanming Zhou of the Nanjing Institute of Geology and Paleontology, write in their new study, "The Weng'an biota and the Ediacaran radiation of multicellular eukaryotes," that the blastula-like fossils from Weng'an likely are close relatives of animals, but are cautious not to rule out the possibility of an algal affinity.

They advance the position that the long march toward animal multicellularity took many evolutionary steps. These evolutionary steps can be retraced only by investigating the intermediate forms preserved in the fossil record, because the closest living sisters of animals are rather simple unicellular organisms. Recognizing such intermediate forms, however, can be challenging because they can appear alien in the eye of any beholder who is trained to look at modern animals.
This research received funding from the National Science Foundation, the National Natural Science Foundation of China, the Ministry of Science and Technology of China, and the Chinese Academy of Sciences.

The authors of the National Science Review paper include Shuhai Xiao, Drew Muscente, Andrew Wood, and Nicholas Polys from Virginia Tech; Lei Chen, Chuanming Zhou, and Xunlai Yuan from Nanjing Institute of Geology and Paleontology, and James D. Schiffbauer from the University of Missouri.

See the article:

Shuhai Xiao, A. D. Muscente, Lei Chen, Chuanming Zhou, James D. Schiffbauer, Andrew D. Wood, Nicholas F. Polys, Xunlai Yuan. "The Weng'an biota and the Ediacaran radiation of multicellular eukaryotes".
National Science Review,

The National Science Review is the first comprehensive scholarly journal released in English in China that is aimed at linking the country's rapidly advancing community of scientists with the global frontiers of science and technology. The journal also aims to shine a worldwide spotlight on scientific research advances across China.

Science China Press

Related Evolution Articles:

Artificial evolution of an industry
A research team has taken a deep dive into the newly emerging domain of 'forward-looking' business strategies that show firms have far more ability to actively influence the future of their markets than once thought.
Paleontology: Experiments in evolution
A new find from Patagonia sheds light on the evolution of large predatory dinosaurs.
A window into evolution
The C4 cycle supercharges photosynthesis and evolved independently more than 62 times.
Is evolution predictable?
An international team of scientists working with Heliconius butterflies at the Smithsonian Tropical Research Institute (STRI) in Panama was faced with a mystery: how do pairs of unrelated butterflies from Peru to Costa Rica evolve nearly the same wing-color patterns over and over again?
Predicting evolution
A new method of 're-barcoding' DNA allows scientists to track rapid evolution in yeast.
Insect evolution: Insect evolution
Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich have shown that the incidence of midge and fly larvae in amber is far higher than previously thought.
Evolution of aesthetic dentistry
One of the main goals of dental treatment is to mimic teeth and design smiles in the most natural and aesthetic manner, based on the individual and specific needs of the patient.
An evolution in the understanding of evolution
In an open-source research paper, a UVA Engineering professor and her former Ph.D. student share a new, more accurate method for modeling evolutionary change.
Chemical evolution -- One-pot wonder
Before life, there was RNA: Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich show how the four different letters of this genetic alphabet could be created from simple precursor molecules on early Earth -- under the same environmental conditions.
Catching evolution in the act
Researchers have produced some of the first evidence that shows that artificial selection and natural selection act on the same genes, a hypothesis predicted by Charles Darwin in 1859.
More Evolution News and Evolution Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at