Human activities are driving an endangered monkey species into isolation in Tanzania, where the genetics of the Udzungwa red colobus monkey are undergoing troubling changes. The monkey (Procolobus gordonorum) is considered an indicator species of ecological change.
The situation, researchers say, is mostly driven by the monkeys’ proximity to villages and the deliberate burning of forests by humans to make way for crops and pastures.
“Smaller populations are becoming more isolated, and that makes them more susceptible to a reduction in genetic diversity, inbreeding, and a host of related extinction variables,” says Nelson Ting, an anthropology professor at the University of Oregon.
Ting and an international team of researchers combed five distinct forested areas from 2011 to 2012 and gathered 170 fecal samples for DNA analysis.
The region of fertile soils and forests scattered in valleys and along mountain ridges in the Eastern Arc Mountains is part of the Eastern Afromontane Hotspot. It is home to many plants and animals that live nowhere else in the world.
The team employed a landscape-genetics approach not commonly used in tropical zones to probe genetic differences in 121 different monkeys and see if human activity is playing a role in ecological changes occurring in the region, says Ting, corresponding author of the paper published in the journal Heredity.
Landscape genetics relies on geographic information systems and combines landscape ecology with population genetics. Alone, population genetics allows researchers to see such differences but not explicitly explain why they exist. In this study, the largest genetic differences were found between monkeys that were separated by villages and areas that experienced the highest densities of fires, based on fire data spanning 2000-2007.
“We found that human activities are driving genetic differentiation in these monkeys across this landscape,” Ting says. “This ecosystem is an important one for conservation in general because of the high level of diversity in it. This research is showing that this ecosystem is in a precarious state.
“This monkey is a forest-adapted species that lives in the trees. We really thought that the best explanation for what is driving genetic differentiation would be forest coverage.”
The monkeys’ proximity to villages and human-made fires emerged as most important as the researchers studied multiple variables one at a time. They also looked at such variables as forest coverage, altitude, ruggedness of the terrain and proximity to railroads. All the data were merged into a composite model.
Source: University of Oregon