Nature & Environment
Frogs With No Tadpole Stage Evolution Surprise Scientists
Brooke Miller
First Posted: Sep 11, 2012 07:08 AM EDT
Frogs have different types of evolution and after the study of nearly 720 species it can be safely said that all tadpoles grow into frogs, but not all frogs start out as tadpoles.
The Stony Brook University and George Washington University study has revealed certain surprising evolution of life cycles in fogs and breaks decades of theory and assumptions.
The researchers state that roughly half of all frog species have a life cycle that starts with eggs laid in water, which emerge into aquatic tadpoles, and then go through metamorphosis and become adult frogs.
Whereas the other half, "includes an incredible diversity of life cycles, including species 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," the researchers state.
"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," said John J. Wiens, lead author and an Associate Professor in the Department of Ecology and Evolution at Stony Brook University.
There are many advantages frogs derive because of their evolutionary cycle. "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 Wiens.
The study was carried in the Journal Evolution.
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First Posted: Sep 11, 2012 07:08 AM EDT
Frogs have different types of evolution and after the study of nearly 720 species it can be safely said that all tadpoles grow into frogs, but not all frogs start out as tadpoles.
The Stony Brook University and George Washington University study has revealed certain surprising evolution of life cycles in fogs and breaks decades of theory and assumptions.
The researchers state that roughly half of all frog species have a life cycle that starts with eggs laid in water, which emerge into aquatic tadpoles, and then go through metamorphosis and become adult frogs.
Whereas the other half, "includes an incredible diversity of life cycles, including species 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," the researchers state.
"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," said John J. Wiens, lead author and an Associate Professor in the Department of Ecology and Evolution at Stony Brook University.
There are many advantages frogs derive because of their evolutionary cycle. "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 Wiens.
The study was carried in the Journal Evolution.
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone