In Mozambique, more and more elephants are born without tusks.
The horns of rhinos are sawed off in South Africa to protect them from poachers. Elephants do not need such assistance: some of the animals do not even develop tusks in order to protect themselves from ivory hunters in this way. This was discovered by a team of researchers in Mozambique’s Gorongosa National Park, where poaching was particularly devastating during the 15-year civil war. When the war broke out in 1977, there were still more than 2,000 pachyderms frolicking in the zoo in the center of the Southeast African state, at the end of the millennium there were only 250. At the same time, however, the proportion of female elephants that remained without tusks tripled – from 18.5 to more than 50 percent.
A “classic case of selection,” says Ryan Long, professor of wildlife science at the University of Idaho and one of the authors of the study recently published in Science Magazine.
In the Gorongosa National Park was the headquarters of the rebel force Renamo, which financed itself among other things with the sale of ivory. Since the rebels were not interested in elephants without tusks, they had a five times greater chance of survival and were able to inherit their gene, which is responsible for the absence of tusks, correspondingly more often. The amazing thing is how quickly the selection had an effect in this case, Long told the TV broadcaster “CNN”: “That was because the chances of survival of the elephants without tusks were many times higher.”
Mutation changes diet
So far only female elephants without tusks occur in nature. The researchers managed to find the gene responsible for the mutation. It is located on one of the two X chromosomes of the female jumbos. If this is passed on to a male embryo, it will still die in the womb. The reason for this is not yet known, according to the study.
In the meantime, the elephant population in Gorongosa has recovered somewhat: there are currently almost 800 pachyderms there. However, the high proportion of women without tusks is now detrimental to the jumbo community because around 50 percent of their male offspring die before birth. In addition, the mutation has an impact on the entire biotope because elephant cows without tusks have different feeding behavior. In addition to fighting and digging water holes, the tusks are necessary for cutting trees, lifting branches and debarking logs: if you don’t have the tools, you have to rely on a different diet – especially leaves and grass. The elephants play a special role in African bush and savanna landscapes: They ensure that the bush does not condense into a forest.
“Toothlessness may be an advantage during a civil war,” says Professor Robert Pringle of Princeton University and co-author of the study Selection then proceed in reverse.
As long as poaching remains under control, the proportion of pachyderms with tusks will increase again, predicts Pringle: “There are also some bright spots in the otherwise depressing news from the world of nature.”
