18 February 2019

The continuing evolution of tuskless elephants


An example of natural selection at work:
Hunting gave elephants that didn’t grow tusks a biological advantage in Gorongosa. Recent figures suggest that about a third of younger females—the generation born after the war ended in 1992—never developed tusks. Normally, tusklessness would occur only in about 2 to 4 percent of female African elephants...

New, as yet unpublished, research she’s compiled indicates that of the 200 known adult females, 51 percent of those that survived the war—animals 25 years or older—are tuskless. And 32 percent of the female elephants born since the war are tuskless...

This tuskless trend isn’t limited to Mozambique, either. Other countries with a history of substantial ivory poaching also see similar shifts among female survivors and their daughters. In South Africa, the effect has been particularly extreme—fully 98 percent of the 174 females in Addo Elephant National Park were reportedly tuskless in the early 2000s...
There is a downside -

Tusks are essentially overgrown teeth. Yet they’re typically used for most tasks of daily living: digging for water or vital minerals in the ground, debarking trees to secure fibrous food, and helping males compete for females...

The work elephants do with their tusks is vital for other animals too. Elephants’ “role as a keystone species to topple trees and dig holes to access water is important for a variety of lower species that depend on them... If elephants are changing where they live, how quickly they move, or where they go, it could have larger implications for the ecosystems around them.

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