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Ant Family Tree Emphasizes Importance Of Tropics In Evolutionary History

April 22, 2013

Brett Smith for redOrbit.com – Your Universe Online

Scientists currently have two prevailing theories about the high degree of biodiversity in the areas around the tropics: some believe that climate acts as a “museum,” allowing older lineages to persist through time. Others, however, see the tropics as a “cradle,” where new species are able to germinate and thrive.

According to a new report in the journal Evolution, a pair of American researchers now says that both theories are correct, and that the tropics act as both a cradle and a museum.

Inspired by previous research that revealed the earliest living ancestors of modern ants, Corrie Moreau of Chicago’s Field Museum and Charles Bell of the University of New Orleans´ Bell Plant Evolution and Phylogenetics Lab looked into how a tropical climate can impact biodiversity by constructing a comprehensive family tree of ants.

Using DNA sequencing techniques, Moreau and Bell described the phylogenetic relationships between over 290 ant specimens to discover species diversification.

The evolutionary tree not only allowed the team to learn how various ant species are interrelated, it also helped to determine the ages of modern ant species, as dates from the fossil record were also included in the research.

The latest study confirmed previous research indicating that two groups of pale, eyeless, subterranean ants are the earliest living ancestors of the modern ants. The researchers also found that the evolutionary origins of modern ants date back to between 139 and 158 million years ago — the Mesozoic Era and the age of the dinosaurs.

The researchers also looked into the geographic origins of ants in an effort to determine whether any single geographic area was more important for their evolution. Moreau and Bell´s analyses found that the Neotropics of South America were highly important to the evolutionary rise of ants. The team found that the Neotropics acted as both a museum — protecting the oldest extant ant groups — as well as a cradle that continues to create new species.

In 2008, scientists reported about the discovery of a new ant species in the soils of the Amazon rainforest. The species was collected from the Amazon region in 2003, but a physiological and genetic analysis allowed the researchers to officially classify it as a subfamily. Because of the new species´ unique physiology — eyeless and pale — the scientists dubbed it Martialis heureka, which translates as “ant from Mars.”

The discovery marked the first time that a new subfamily of ants with living species had been discovered in about 85 years. At the time, researchers predicted that their discovery would help biologists better understand the biodiversity and evolution of ant species.

“This discovery hints at a wealth of species, possibly of great evolutionary importance, still hidden in the soils of the remaining rainforests,” the researchers wrote about their discovery in the Proceedings of the National Academy of Sciences (PNAS).

Scientists believe that ants evolved from wasp-like ancestors, specializing to live in the soil, on the ground or in the trees. The researchers say that their newly discovered species probably evolved features over time that helped it adapt to a subterranean habitat.

Ants are widely regarded as one of the most ecologically important groups of terrestrial organisms. Scientists in both studies noted that protecting the rainforests are vital to the health of various ant species as well as all the countless other organisms that rely on them to survive.


Source: Brett Smith for redOrbit.com - Your Universe Online



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