Inventions of evolution: What gives frogs a face

Jan 13, 2011
This is a specimen of the South African clawed frog (Xenopus laevis), that zoologists at Jena University are doing research on. Credit: Photo: Jan-Peter Kasper/University Jena

Zoologists of the University Jena (Germany) analysed the central factor for the development of the morphologically distinctive features of the tadpoles. "We were able to show that the 'FOXN3' most of all influences the development of the cartilages in the oral region and the gills," professor Dr. Lennart Olsson points out. These structures in particular belong to the evolutionary new developments typical of frogs, which are missing in other amphibians.

"Don't be a frog!" people say in jest when someone hesitates instead of acting straight away. However to be called a frog should actually be a reason to strengthen one's self-confidence. After all are real winners – at least from the point of view of evolutionary biology: Nearly 6.000 species are known today. "In terms of numbers frogs are superior to all the other amphibians, and even mammals", says Professor Dr. Lennart Olsson from the Friedrich Schiller University Jena (Germany). Professor Olsson's research group for Systematic Zoology examines these animals's special secret of success. "We are interested in how the frogs developed in such a great variety and which evolutionary new development is responsible for making frogs so particularly successful", Jennifer Schmidt from Olsson's team explains.

Their evolutionary success is literally written all over the frogs' faces: Certain forms of cartilage and bone structures in the region of the head of the tadpoles are among the frogs' "innovations". These structures only to be found in frogs appear in the oral region. They enable the tadpoles – of the South African claw frog (Xenopus laevis) – particularly well to chip vegetarian food from the soil and from stones or to filter it from the water.

In their latest study which has been published in the science magazine "Journal of Anatomy" together with colleagues from Ulm Jennifer Schmidt analysed the central factor for the development of these morphologically distinctive features of the . It is well known from earlier analyses, that the gene "FOXN3" plays a key role in the embryonal development of the heads of claw frogs. "It is responsible for the normal development of cartilages, bones and muscles", Jennifer Schmidt explains.

In the newly published study the 25 year old doctoral candidate and scholar of the Konrad-Adenauer-Stiftung analysed larvae of the claw frog after the "FOXN3"-gene had been cut off. Then she compared them with untreated larvae. "Our analyses with microCT show that the larvae without an intact 'FOXN3'-gene are developing normally up to a certain time." But then the development slows down, says Jennifer Schmidt. "On the whole these animals grow more slowly." Most of all the cartilages, the bones and muscles don't develop properly. Deformations and loss of functions occur. However not all cartilages and muscles are affected by the cut-off gene. "We were able to show that the 'FOXN3' most of all influences the development of the cartilages in the oral region and the gills", Professor Olsson points out. These structures in particular belong to the evolutionary new developments typical of frogs, which are missing in other amphibians. Jennifer Schmidt would like to continue her analyses in her thesis. "We are going to compare the embryonal development of the claw frogs with those of other amphibians", the zoologist says. It would be interesting to find out to what extent the genetic control of those new developments changed in the course of the evolution.

Explore further: Male monkey filmed caring for dying mate (w/ Video)

More information: Schmidt J, Schuff M, Olsson L: A role for FoxN3 in the development of cranial cartilages and muscles in Xenopus laevis (Amphibia: Anura: Pipidae) with special emphasis on the novel rostral cartilages. J Anat. 2010. doi: 10.1111/j.1469-7580.2010.01315.x

Provided by Friedrich-Schiller-Universitaet Jena

5 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Frogs with disease-resistance genes may escape extinction

Jul 16, 2008

As frog populations die off around the world, researchers have identified certain genes that can help the amphibians develop resistance to harmful bacteria and disease. The discovery may provide new strategies to protect ...

Endangered gopher frogs bred in zoo

Apr 08, 2008

Tennessee's Memphis Zoo says it has successful started the first captive breeding program for endangered Mississippi gopher frogs.

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

Apr 18, 2014

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

Apr 17, 2014

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 0

More news stories

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Growing app industry has developers racing to keep up

Smartphone application developers say they are challenged by the glut of apps as well as the need to update their software to keep up with evolving phone technology, making creative pricing strategies essential to finding ...

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.