Elephant conservation is a major priority in southern Africa, but habitat loss and urbanization are increasingly confining the widespread pachyderms to protected areas such as game reserves. The risk? Confined populations can become genetically isolated over time, making elephants more vulnerable to disease and environmental change.
A recent study from the University of Illinois Urbana-Champaign and the University of Pretoria in South Africa shows how African wildlife managers can create and optimize corridors for elephant movements across a region of seven countries. The study provides a map showing landscape connections that would support elephant habitat needs and allow greater gene flow between populations.
“Other research groups have integrated genetic and spatial data before, but usually this is done on a more local scale. Our research group was the first to combine both types of data for South African elephants over such a large geographical area,” says lead author Alida de Flamingh. , who completed the study as part of her doctoral program in the Department of Animal Sciences, part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at Illinois. She is now a postdoctoral researcher at the Carl R. Woese Institute for Genomic Biology.
Scale is meaningful because African elephants have a very large home range – they can roam up to 11,000 square kilometers, or more than 2.7 million hectares – and they often travel long distances to avoid unsuitable habitats. Capturing that scale in a single analysis was no easy task.
“This was a huge effort. We set out with our partners in the Conservation Ecology Research Unit at the University of Pretoria to collect non-invasive DNA samples from elephant dung across its range,” de Flamingh said. “CERU also contributed data from GPS trackers of 80 collared elephants at nearly 54,000 locations.”
GPS collar data shows how elephants move through the landscape, but cannot indicate whether that movement leads to gene flow. Conversely, DNA data documents gene flow, but cannot show how elephants moved to make that happen. Integrating the two datasets required a landscape genetics approach.
“Landscape genetics adapts some ideas from electrical circuit theory to discuss how animals can move and achieve gene flow. Our approach looks at the resistances or costs that elephants encounter as they move along multiple paths across the region, taking into account with the possibility of losing or gaining individual paths,” says co-author Nathan Alexander, a postdoctoral researcher at the Illinois Natural History Survey. Alexander worked on the project during his doctoral program in ACES’s Department of Natural Resources and Environmental Sciences.
The costs in this case include steep slopes, arid areas with little to no vegetation, dense human settlements and areas far from water. The researchers combined these environmental challenges with DNA data to explain how elephants can navigate their habitat, identifying key routes to maintain gene flow through protected areas.
“We did not find a simple linear relationship where more suitable habitats are less expensive. Instead, we found a distinctly non-linear pattern where the least suitable habitats have the greatest impact on the movement or distribution of elephants across the landscape,” said De Flamingh. “Intermediate habitats don’t necessarily dictate their movements as much as these really, really unsuitable habitats. That’s a positive, if you think about it. They are tolerant of intermediate habitats and can still move through them.”
What qualifies as “really, really unsuitable” habitat? The researchers identified areas such as the vegetation-free Makgadikgadi Salt Pans in Botswana, as well as densely populated human settlements. Providing connections for elephants that avoid these areas will also reduce human-elephant conflict, a clear threat to elephants.
De Flamingh said insights from this research can help government agencies and NGOs in southern Africa develop robust conservation initiatives on the ground.
“South Africa has the largest number of elephants in all of Africa. So any conservation efforts there, especially those that avoid human-elephant conflict, would protect quite large elephant populations,” said senior author Al Roca, professor of animal sciences at ACES. . “Our partners at CERU, as well as our funders – the International Fund for Animal Welfare and the U.S. Fish and Wildlife Service’s African Elephant Conservation Fund – are very critical in these efforts.”
The study, “Integrating habitat suitability modeling with gene flow improves the delineation of landscape connectivity among African savanna elephants,” was published in Biodiversity and nature conservation. The article is dedicated to the memory of co-author Rudi van Aarde, who as head of CERU played an important role in launching the study and who died while the research was still ongoing.
Roca is also affiliated with the Carl R. Woese Institute for Genomic Biology, the Illinois Natural History Survey and the School of Information Sciences at Illinois.
