Mozambique: evolution of the elephant without tusks linked to ivory hunting

A new study suggests that severe ivory poaching in parts of Mozambique led to the evolution of tuskless elephants.

I study published in the journal Science found that a previously rare genetic condition had become more common in Gorongosa National Park as poaching ivory used to finance a civil war pushed the species to the brink of extinction.

Before the war, about 18.5% of females were naturally tuseless.

But that figure has risen to 33% among elephants born since the early 1990s.

About 90% of Mozambique’s elephant population was slaughtered by fighters from both sides of the 1977-1992 civil war. Poachers sold ivory to finance the fierce conflict between government forces and anti-Communist insurgents.

As in eye color and blood type in humans, genes are responsible for elephants to inherit tusks from their parents.

Tuskless elephants have been left alone by hunters, increasing the likelihood that they will reproduce and pass the tuskless trait to their offspring.

Researchers have long suspected that the trait, found only in females, was related to the elephant’s sex. After the genomes of elephants with and without tusks were sequenced, the analysis revealed that the trend was linked to a mutation on the X chromosome that was fatal in males, which did not develop correctly in the uterus and dominated in females.

Study co-author Professor Robert Pringle of Princeton University pointed out that the discovery could have a number of long-term effects for the species.

He noted that because the tuseless trait was fatal to male offspring, it was possible that fewer elephants would be born overall. This could slow the recovery of the species, which now stands at just over 700 in the park.

‘The absence of fangs could be advantageous during a war,’ said Professor Pringle. “But this has a cost.”

Another potential ripple effect is changes in the broader landscape, as the study revealed that animals with and without tusks eat different plants.

But Professor Pringle pointed out that the trait was reversible over time as populations recovered from the brink of elimination.

“So we actually expect this syndrome to decrease in frequency in our study population, as long as the conservation picture continues to remain as positive as it has recently been,” he said.

“There is such a bleak of depressing news about biodiversity and humans in the environment and I think it’s important to point out that there are some bright spots in that picture.”