The multicolored poison frogs in the Amazon have been as diverse as today thanks to the many ancestors moving from the Andes to this area over the past 10 million years, new research from the University of Texas at Austin for know.
This is the first study to show that the Andes is the main diversification source of the Amazon basin, one of the largest bio-diversity centers on Earth. This finding contradicts the idea that Amazon's diversification is a self-evolving result within this rainforest.
Researcher Juan Santos, lead author of the study, said: 'Basically, the Amazon basin is home to many South American frog species. The poison frogs there come from many different places, most notably the Andes Mountains, for many millions of years. Research shows that you cannot fully understand Amazon's biodiversity but only look at the basin itself. Those poor areas also play a very important role. '
Santos and Dr. David Cannatella, professor of biology, published their findings this month in the journal PLoS Biology.
There have been predictions that most of the evolution of the Amazon basin biodiversity took place over the past 2 million years, a very short period of history.
Santos and Cannatella looked into the past 45 million years ago by using new biogeographic techniques to create the evolutionary history of poison frogs in space and time. Because of the lack of extensive fossil records about this tropical forest, they used DNA sequences to understand the evolutionary history of poisonous frogs.
Poisonous frogs, or dendrobatids, are diverse and widely distributed throughout Neotropics, areas of Central and South America. Scientists have created an evolutionary tree using 223 of the 353 poison frog species known in this area.
When analyzing the evolutionary relationship between poisonous frogs, they found that the diversity of Amazon was the result of at least 14 dispersal of ancestral frog species into this area beginning 23 million years ago.
All of the poisonous frogs in the Amazon evolved from these ancestors, and most came from the Andes Mountains.
The Amazon basin has changed a lot since 23 million years ago . An inland water system appeared and disappeared. The Andes range began to rise (about 15 million years ago) and the Amazon River formed (about 9 million years ago).
Most of the moves from the Andes appeared 1 to 7 million years ago, when the modern rainforest of the Amazon River was forming.
Santos said: 'There is a repeated scattering of frogs from the Andes after the inland swamp disappears from Amazon.'
These frogs then evolved into 70 different species today in the Amazon basin
Scientists also found that some frogs have left the Amazon basin to surrounding areas and areas in the Neotropics.
The evolution and diversification of poisonous frogs is still ongoing, especially in the Amazon and Chocó rainforest areas (a narrow tropical forest area along the Pacific Northwest and South American coasts), and regions around Central America.
Cannatella said that many tropical plants and animals in the Amazon may also have complex time and geography history like poison frogs.
He concluded: 'The Amazon rainforest area not only gradually accumulates diversity over time. Ancestral frogs move in and out of this area, so we can predict that the only species in this humid rainforest area will probably have a dispersal, evolutionary cycle. Similar diversification '.