The findings of a new study led by the Leibniz-IZW on Namibian free-ranging cheetahs (Acinonyx jubatus jubatus) demonstrate that epigenetic mechanisms might play an important role in how animals develop different phenotypes – that is, different phenotypical characteristics – despite having a low genetic diversity.
Male cheetahs begin their adult lives as so-called floaters. They do not occupy a territory but roam over large areas, either alone or in small groups of up to three brothers. Some of them manage to take over a territory through deadly fights and become territorial males. Soon after, they alter their phenotype within a couple of months. As territorial males they become physically stronger, behave more aggressively and move within a significantly smaller area, at which centre the cheetahs` marking trees are located.
The scientists hypothesised that such changes cannot be explained by genetic differences, but might be epigenetically controlled. This means that DNA methylations are regulating the genes` activity without altering the DNA sequence itself. DNA methylation is the binding of chemical groups to the DNA, which can alter the level of gene expression.

IZW Long-Term Cheetah Research Project in Namibia

For the study, the research team used blood samples, weight and age data from the Leibniz-IZW Cheetah Research Project in Namibia. Blood samples were available from ten male cheetahs at both life history stages: first, when the animals were still floaters, and later, after they had taken over a territory. This enabled the researchers to identify and compare DNA methylation patterns in the same individuals before and after the transition.

“Furthermore, the body measurements of floaters that remained floaters into old age remained largely unchanged. This contrasts with floaters that later took over a territory,” explains Colin Vullioud, lead author and data analyst at the Leibniz-IZW. “In addition, we have identified potential epigenetic biomarkers that can be used to distinguish floaters from territorial males.”
Dr Bettina Wachter, scientist in the Department of Evolutionary Ecology at the Leibniz-IZW and head of the cheetah research project in Namibia, says: “A relevant and very unusual aspect of cheetahs is that males undergo physical and behavioural changes after they won a fight over a territory. In other mammalian species, males normally engage in a fight when they are already strong and then remain strong after having taken over the territory. Therefore, we were able to demonstrate which genes were differently methylated when shifting from floater to territorial male phenotype.”

Epigenetic Markers for Species Conservation

“Our findings are important because they show that even species with low genetic diversity are adaptable. The epigenetic flexibility may help individuals to develop different phenotypes, which is particularly important under rapidly changing environmental conditions,” says Weyrich.

The researchers emphasise that the study cannot demonstrate a cause-and-effect relationship. While the observed methylation changes in cheetahs are associated with the transition from floater to territorial male, the available data do not allow to determine whether these changes initiate or accompany the transition, or are a consequence of the altered life history stage.