Nav: Home

Mechanisms explaining positional diversity of the hindlimb in tetrapod evolution

August 18, 2017

Nagoya, Japan - In the evolution of tetrapods, the position of the hindlimb has diversified along with the vertebral formula, which is the number of small bones forming the vertebra. Tetrapods, as the name implies, are species that have four feet. However, this group also includes many other animals without four or any feet, such as snakes and birds. This is because tetrapods include all the organisms, living and extinct, that descended from the last common ancestor of amphibians, reptiles and mammals, even if they have secondarily lost their "four feet".

Although researchers have long studied tetrapod anatomy, how the species-specific position of the body parts of these species--for example, the hindlimb position along the body--are formed in early development remains unclear. Elucidating this mystery will be a major step in evolution biology.

This crucial piece of the puzzle has finally been found by a team of researchers from Nagoya University in Japan. The researchers demonstrated that a protein called GDF11, which is involved in embryonic development, plays a vital role in the eventual position of the sacral vertebrae and the hindlimb. The study results were published in July 2017 in Nature Ecology & Evolution.

"In laboratory mice that do not produce the protein GDF11, we have noted that the sacral vertebrae and the hindlimbs are shifted more to the back," said Yoshiyuki Matsubara, researcher at the Division of Biological Science and first author of the study.

To arrive at that conclusion, the research team started by analyzing the expression pattern of the gene of interest and examining the relationship between the pattern and the prospective position of the spine and hindlimb at different development stages in chicken embryos. Next, they tested whether hindlimb positioning can be manipulated by changing the timing of GDF11 activity in the embryos. Lastly, to fully elucidate the role of GDF11 in diversification of the hindlimb position in tetrapods, the team examined the correlation between Gdf11 expression and hindlimb positioning in eight tetrapod species, including the African clawed frog, Chinese soft-shelled turtle, ocelot gecko, Japanese striped snake, chick, quail, emu and mouse.

"Our results also suggest that species-specific hindlimb positioning may have been an effect of the change in the timing or rate of events in the gene that expresses GDF11 during embryonic development," said Takayuki Suzuki, last author of the study.

According to their conclusion, snakes have a long trunk because initiation timing of Gdf11 expression in the developmental stage is much later than that in other tetrapod species.

Based on the present observations, the researchers will propose a model to explain the coupling of sacral-hindlimb positioning in tetrapod evolution. This will lead to a deeper understanding of the diversification of lineage-specific tetrapod hindlimb positions, a valuable piece of information in the field of evolution.

-end-

The article, "Anatomical integration of the sacral-hindlimb unit coordinated by GDF11 underlies variation in hindlimb positioning in tetrapods" was published in at Nature Ecology & Evolution at DOI: 10.1038/s41559-017-0247-y

Nagoya University

Related Evolution Articles:

Prebiotic evolution: Hairpins help each other out
The evolution of cells and organisms is thought to have been preceded by a phase in which informational molecules like DNA could be replicated selectively.
How to be a winner in the game of evolution
A new study by University of Arizona biologists helps explain why different groups of animals differ dramatically in their number of species, and how this is related to differences in their body forms and ways of life.
The galloping evolution in seahorses
A genome project, comprising six evolutionary biologists from Professor Axel Meyer's research team from Konstanz and researchers from China and Singapore, sequenced and analyzed the genome of the tiger tail seahorse.
Fast evolution affects everyone, everywhere
Rapid evolution of other species happens all around us all the time -- and many of the most extreme examples are associated with human influences.
Landscape evolution and hazards
Landscapes are formed by a combination of uplift and erosion.
New insight into enzyme evolution
How enzymes -- the biological proteins that act as catalysts and help complex reactions occur -- are 'tuned' to work at a particular temperature is described in new research from groups in New Zealand and the UK, including the University of Bristol.
The evolution of Dark-fly
On Nov. 11, 1954, Syuiti Mori turned out the lights on a small group of fruit flies.
A look into the evolution of the eye
A team of researchers, among them a zoologist from the University of Cologne, has succeeded in reconstructing a 160 million year old compound eye of a fossil crustacean found in southeastern France visible.
Is evolution more intelligent than we thought?
Evolution may be more intelligent than we thought, according to a University of Southampton professor.
The evolution of antievolution policies
Organized opposition to the teaching of evolution in public schoolsin the United States began in the 1920s, leading to the famous Scopes Monkey trial.

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: Radiolab

Radiolab Presents: Anna in Somalia
This week, we are presenting a story from NPR foreign correspondent Gregory Warner and his new globe-trotting podcast Rough Translation. Mohammed was having the best six months of his life - working a job he loved, making mixtapes for his sweetheart - when the communist Somali regime perp-walked him out of his own home, and sentenced him to a lifetime of solitary confinement.  With only concrete walls and cockroaches to keep him company, Mohammed felt miserable, alone, despondent.  But then one day, eight months into his sentence, he heard a whisper, a whisper that would open up a portal to - of all places and times - 19th century Russia, and that would teach him how to live and love again. 
Now Playing: TED Radio Hour

Future Consequences
From data collection to gene editing to AI, what we once considered science fiction is now becoming reality. This hour, TED speakers explore the future consequences of our present actions. Guests include designer Anab Jain, futurist Juan Enriquez, biologist Paul Knoepfler, and neuroscientist and philosopher Sam Harris.