Researchers discover unexpected patterns in evolution of frog life cycles

September 10, 2012
Credit: Stony Brook University

All tadpoles grow into frogs, but not all frogs start out as tadpoles, reveals a new study on 720 species of frogs to be published in the journal Evolution.

The study, "Phylogenetic analyses reveal unexpected patterns in the evolution of reproductive modes in frogs," led by John J. Wiens, an Associate Professor in the Department of at Stony Brook University, and colleagues Ivan Gomez-Mestra from the DoƱana Biological Station in Seville, Spain, and R. Alexander Pyron from George Washington University, uncovers the surprising evolution of in frogs.

Roughly half of all have a life cycle that starts with eggs laid in water, which hatch into aquatic , and then go through metamorphosis and become adult frogs. The other half, according to the authors, "includes an incredible cycles, including in which eggs are placed on leaves, in nests made of foam, and even in the throat, stomach, or back of the female frog. There are also hundreds of species with no tadpole stage at all, a reproductive mode called direct development."

For decades, it has been assumed that the typical mode (with eggs and tadpoles placed in water) gave rise to direct development through a series of gradual intermediate steps involving eggs laid in various places outside water. "However, the results show that in many cases, species with eggs and tadpoles placed in water seem to give rise directly to species with direct development, without going through the many seemingly intermediate steps that were previously thought to be necessary," Dr. Wiens said.

"The results also suggests that there many potential benefits for species that have retained aquatic eggs and tadpoles, such as allowing females to have more offspring and to colonize regions with cooler and drier climates. These advantages may explain why the typical frog life cycle has been maintained for more than 220 million years among thousands of species," said Professor Wiens.

Explore further: Frogs with disease-resistance genes may escape extinction

Related Stories

Frogs with disease-resistance genes may escape extinction

July 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 ...

Eradicating cane toads with 'their own medicine'

November 14, 2011

Sydney University biologists have discovered cane toad tadpoles (Bufo marinus) communicate using chemicals excreted into the water, a finding that may help to impede the Cane Toad invasion of the Kimberley.

New boulder frog discovered

October 7, 2011

(PhysOrg.com) -- Scientists have discovered two new species of boulder-dwelling frogs, hidden in remote areas of rainforest in north-east Queensland.

Inventions of evolution: What gives frogs a face

January 13, 2011

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 ...

Recommended for you

Seasonal warming leads to smaller animal body sizes

March 28, 2017

Changes in the body size of animals measured under controlled laboratory conditions have been shown to closely match changes in body size with seasonal warming in nature, according to research from Queen Mary University of ...

Stop eating! You are full

March 28, 2017

Researchers have identified a molecule sent by fat cells to the fly brain that senses when they have had enough food and inhibits feeding, according to a study publishing March 28 in the open access journal PLOS Biology by ...

A molecular on/off switch for CRISPR

March 28, 2017

Picture bacteria and viruses locked in an arms race. For many bacteria, one line of defense against viral infection is a sophisticated RNA-guided "immune system" called CRISPR-Cas. At the center of this system is a surveillance ...

Female menstrual cycle in a dish

March 28, 2017

Northwestern Medicine has developed a miniature female reproductive tract that fits in the palm of your hand and could eventually change the future of research and treatment of diseases in women's reproductive organs.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

KalinForScience
not rated yet Sep 10, 2012
not all tadpoles grow into frogs.., some grow into salamanders, newts, etc... :)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.