Question

Elephant Tusklessness
Sclentists working in Gorongosa National Park are trying to determine the genes responsible for tusk development in elephants. Normally, more than 90% of female African elephants have tusks. But in Gorongosa National Park, which has a history of heavy poaching, about 50% of the elephants are tuskless. To study this striking phenomenon, scientists are searching for the gene or genes responsible for tusk development and how variations in these genes can lead to tusklessness.
During the Mozambican Civil War (1977-1992), elephants were heavily hunted for ivory. After the war, researchers documented a significant increase in tuskless female elephants in Gorongosa National Park. Figure 1 shows the percentage of tuskless females pre- and post-war. This change illustrates how human actions can alter evolutionary pressures.

The trend supports that tusklessness is an ___
trait in the context of intense poaching pressure.

Answer 1

adaptive

Explanation: under intense poaching, tuskless elephants have a survival advantage, so alleles for tusklessness are being favored by natural selection (directional selection), increasing their frequency.