The cool temperate rainforests of southern South America (37-55º south latitude) are isolated from the warm tropical Amazonian rainforest by arid regions and mountains. Dating from the late Cretaceous forests of the Gondwanan supercontinent, the isolated southern temperate rainforest ecosystem has produced endemic species. This forest system has been threatened by deforestation, but recent measures are being initiated to protect this habitat. This area is an urgent target for biodiversity analysis and ecological research that is needed to guide appropriate conservation strategy.
This southern rainforest holds the only species in the Order Microbiotheria, which is one of the seven orders of marsupial mammals. This species is the most closely related of the American marsupials to the highly diversified Australian lineages. This small, rare, opossum-like relict, Dromiciops gliroides, known as "Monito del Monte," inhabits remaining patches of old-growth forest in southern Chile, including the Isla Grande de Chiloé, and an adjacent area of Argentina. The Monito del Monte forages at night in trees and bushes, and consumes both insects and fruit.
Surprisingly little is known of the ecology, life history, and behavior of the Monito del Monte. We are exploring the basic ecology and natural history of this species in Chile at the field station of the "Senda Darwin" Foundation on the island of Chiloé. We are monitoring a natural population throughout its annual cycle of breeding, recruitment of juveniles into the population, and hibernation. We expect to determine spatial and social relationships, using DNA markers to identify the genetic basis of population structure. A study of diet and habitat use will help to define the role of D. gliroides in this ecosystem, including dispersal of seeds from fruits.
Southern South America and its temperate rainforest have been shaped by the geological uplift of the Andean Cordillera in the Oligocene. More recently Pleistocene climatic and glacial cycles have produced periods of expansion and reduction of the range of this forest habitat. This process included fragmentation, isolation, and re-invasion of the forest and its inhabitants, including the Monito del Monte. Our phylogeographic study of D. gliroides is focusing on the response of the geographic range of the species to late Pleistocene glacial cycles. We expect to reveal the possible refugia that maintained the Monito del Monte during peak glaciation. These sites could include the northern end of the island of Chiloé, mainland Chile, or both. We will employ the mitochondrial genome and several genetic analyses to address this issue.
Chris Himes is a Burke Museum graduate student working on his Ph.D. in Zoology. He is interested in evolution, biogeography, and life history of mammals and works in the temperate rain forest environments of both North and South America.
Jim Kenagy is Curator of Mammals at the Burke Museum and Professor of Zoology in the Biology Department.
The Burke researchers are also collaborating with Chilean colleagues on a variety of aspects of this research:
Juan Armesto, Pontificia Universidad Católica de Chile,
Juan Luis Celis, Universidad de Chile,
Cecilia Smith, Universidad de Chile,
Milton Gallardo, Universidad Austral de Chile