Animals may have hitched rides on natural rafts to populate Madagascar

Posted By: Staff
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Washington, January 21 (ANI): In a new research, a pair of scientists has suggested that animals may have populated Madagascar by hitching rides on natural rafts blown out to sea.

According to professors Matthew Huber of Purdue and Jason Ali of the University Hong Kong, the prevailing flow of ocean currents between Africa and Madagascar millions of years ago would have made such a trip not only possible, but fast, too.

The findings are based on a three-year computer simulation of ancient ocean currents.

Rafting would have involved animals being washed out to sea during storms, either on trees or large vegetation mats, and floating to the mini-continent, perhaps while in a state of seasonal torpor or hibernation.

Anthropologists and paleontologists have good reason to be interested in Madagascar's animals.

Madagascar has more unique species of animals than any location except Australia, which is 13 times larger.

The island's population includes 70 kinds of lemurs found nowhere else and about 90 percent of the other mammals, amphibians and reptiles are unique to its 226,656 square miles.

There are no large mammals such as apes, giraffes, lions or elephants, indigenous to Madagascar.

Only small species such as lemurs, hedgehog-like tenrecs; rodents; mongoose-like carnivores; and similar animals populate the island.

The animals of Madagascar appear to have arrived in occasional bursts of immigration by species rather than in a continuous, mixed migration.

They likewise appear to have evolved from single ancestors, and their closest relatives are in Africa, according to scientists.

This fulfills a theory put forward by paleontologist and evolution theorist George Gaylord Simpson in 1940.

Simpson introduced the concept of a "sweepstakes" process to explain the chance of raft colonization events taking place through vast stretches of geological time.

Once the migrants arrived on the world's fourth largest island, their descendants evolved into the distinctive, and sometimes bizarre forms seen today.

"What we've really done is prove the physical plausibility of Simpson's argument," Huber said.

The Purdue professor was able to show through his simulations that 20 million to 60 million years ago, when scientists have determined ancestors of present-day animals likely arrived on Madagascar, currents flowed east, toward the island.

Climate modeling showed that currents were strong enough - like a liquid jet stream in peak periods - to get the animals to the island without dying of thirst.

The trip appears to have been well within the realm of possibility for small animals whose naturally low metabolic rates may have been even lower if they were in torpor or hibernating. (ANI)

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