Ivory poaching triggers evolution of tuskless elephants

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Decades of heavy poaching led to the development of toothless elephants in parts of Africa, scientists have found.

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Tusklessness became more common among female elephants in Mozambique’s Gorongosa National Park after rampant ivory poaching during the country’s 15-year civil war.

A small proportion of females have always been born without teeth, but experts in Gorongosa began to notice the situation more after the end of the war in 1992, when 90 percent of the park’s elephant population was wiped out.


The researchers found that more than 50 percent of female elephants born in Gorongosa between the start of the war and the year 2000 were born without teeth, a three-fold increase.

Ryan Long, an associate professor of wildlife science at the University of Idaho and one of the researchers, said the elephant population fell from about 2,000 to about 250 during this period.

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“During the war, Gorongosa was essentially the geographic center of the conflict,” Mr Long told CNN. “As a result, there were a large number of soldiers in the area and a lot of allied motivation … to buy arms and ammunition to kill elephants and sell ivory. The resulting level of poaching was very intense.”

Mr Long said the impact of the war on Gorongosa’s elephant was a rare example of rapid development. Tusklessness among the next generation fell again to 33 percent.

“Evolution is a change in genetic characteristics within a population over successive generations, and based on the results of our study, the shift toward tusklessness among female elephants in Gorongosa fits this definition perfectly,” he said.

“The fact that this happened so rapidly is actually rare, and is a direct function of the strength of the selection,” he said. “In other words, it happened so quickly because tuskless women were much more likely to survive the war, and thus much more likely to pass their genes on to the next generation.”

NS Research provided scientists with a better understanding of why tusklessness affects women but not men: it is genetically fatal.

Mr Long said toothlessness was linked to genetic variation of the X-chromosome. Tuskless females have one X-chromosome containing information for developing tusks and one without.

“When a toothless female conceives a male offspring, that male has a 50/50 shot of receiving the affected X-chromosome from its mother. If it receives the ‘normal’ chromosome it will survive Will live and be born with the genetic information needed to produce teeth.”

However, a male who inherits the chromosome without teeth will die in the womb.

The researchers said they still do not fully understand the exact characteristics of the genetic variant.

Mr Long said Gorongosa’s population is doing well, which has recovered to around 800.

“They have clearly adapted to life without teeth, but there is a lot we don’t know,” he said.


Credit: www.independent.co.uk /

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