Decline of aspens swells population of rodents that carry sin nombre virus

Susan Milius in Science News: Recent diebacks of aspen trees in the U.S. West may end up increasing the risk posed by a lethal human pathogen, a new study suggests. A tree-killing syndrome called sudden aspen decline that has wiped out swaths of trees across the West in the past decade has also changed the kinds, numbers and interactions of creatures living around the trees, researchers have found — including some carriers of human disease. Deer mice at hard-hit sites in 2009 were almost three times as likely to carry sin nombre virus — which can be fatal to humans — compared with mice in less-ravaged aspen stands, Erin Lehmer of Fort Lewis College in Durango, Colo., and her colleagues reported January 4 at the annual meeting of the Society for Integrative and Comparative Biology.

The deer mouse Peromyscus maniculatus looks ironically cute in pictures at meeting presentations, but the Centers for Disease Control and Prevention ranks it as the main rodent reservoir for sin nombre virus. Infected deer mice don’t show many symptoms, but people inhaling virus wafting from mouse urine or saliva can get quite sick with hantavirus pulmonary syndrome.

…“Both plant diseases and animal diseases are rapidly emerging globally, and we should be looking for ways that the two might interact,” said Richard Ostfeld of the Cary Institute of Ecosystem Studies in Millbrook, N.Y., who studies Lyme disease transmission….

Transmission electron micrograph of the Sin Nombre Hantavirus. Hantaviruses that cause Hantavirus pulmonary syndrome (HPS) are carried in rodent droppings, especially the deer mouse. Centers for Disease Control

Rodent size linked to human population and climate change

University of Illinois (Chicago): You probably hadn't noticed -- but the head shape and overall size of rodents has been changing over the past century. A University of Illinois at Chicago ecologist has tied these changes to human population density and climate change. The finding is reported by Oliver Pergams, UIC research assistant professor of biological sciences, in the July 31 issue of PLoS One.

Pergams said that such size-and-shape changes in mammals, occurring around the world in less than a century, are quite substantial. He had done earlier studies on a century's worth of anatomic changes between two geographically isolated rodents -- Channel Island deer mice from coastal California and white-footed mice northwest of Chicago -- and noted fast change among both.

"I suspected they weren't unique examples," he said. "I wondered whether these changes were occurring elsewhere, whether they were global in nature, and what some of the causes may be."

Pergams examined specimen rodents from museums around the world, including the big collections held at Chicago's Field Museum and the Smithsonian in Washington. Altogether, he recorded more than 17,000 body and skull measurements from 1,300 specimens from 22 locations in Africa, the Americas and Asia. The animals were collected from 1892 to 2001, and Pergams compared those from before 1950 to those collected after.

…While Pergams' study was by no means comprehensive, it was the first attempt of its kind to examine data on mammals from many global locations to find links between morphological change and variables such as population density and changing climate….

The northern roofs of the Cathedral Notre-Dame in Amiens, France conceal this sculpted rodent from the ground. Shot by Eusebius (Guillaume Piolle), Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported License.