The First Phylogeographic Analysis of a Dry Region in Northern South America

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A study in the new issue of the Journal of Mammalogy focuses on the historic structure of the opossum populations in an attempt to gain insights regarding the impact of geologic and climatic events on the evolution of the opossum from dry habitats in northern South America.

Journal of Mammalogy 95(6)

By taking geographic samplings of the opossum and comparing DNA sequences, the authors tracked the evolutionary patterns of the species as it diverged and how the environment impacted their development.

Journal of Mammalogy – Unlike what flourishes in the rainforests of South America, the plant and animal life in the seasonally dryer climates have received very little attention. It has taken until 2014 for the first study to be published regarding the history of the geographic analysis of flightless vertebrate in the dry climates of northern South America.

The article “Phylogeography of Marmosa robinsoni: Insights into the biogeography of dry forests in northern South America,” in the Journal of Mammalogy focuses on Marmosa robinsoni (Robinson’s mouse opossum). This species mainly inhabits deciduous forests, gallery forests surrounded by savannas, and extremely dry shrublands. The authors focused on the historic structure of the opossum populations in an attempt to gain insights regarding the impact of geologic and climatic events on the evolution of the opossum from dry habitats in northern South America.

It was supposed that two groups of opossum split into the eastern and western parts of northern South America approximately 3.65 million years ago. By taking geographic samplings of the opossum and comparing DNA sequences, the authors tracked the evolutionary patterns of the species as it diverged and how the environment impacted their development.

The authors were surprised to learn that the isolated opossum populations from northwestern Venezuela were not closely related to the mainland populations, that were their closest geographical proximate. They were most closely related to the distant populations in Colombia and Panama. On the other hand, populations from central and eastern Venezuela are closely related to those on the islands of Trinidad and Tobago. The authors believe that this may have occurred due to glacial cycles and the lowering of sea level that exposed dry-land connections between Trinidad and mainland Venezuela, and between Trinidad and Tobago. Future research is necessary to confirm the authors’ hypothesis and to continue to study additional plants and animals in the dry climate of northern South America.

Full text of the article, “Phylogeography of Marmosa robinsoni: insights into the biogeography of dry forests in northern South America,” Journal of Mammalogy, Vol. 95, No. 6, 2014, is now available.

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About the Journal of Mammalogy

The Journal of Mammalogy, the flagship publication of the American Society of Mammalogists, is produced six times per year. A highly respected scientific journal, it details the latest research in the science of mammalogy and was recently named one of the top 100 most influential journals of biology and medicine in the last century by the Special Libraries Association. For more information, visit http://www.mammalogy.org/.

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Jason Snell
Allen Press
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