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.

Using evidence from the tuskless elephant case, explain how natural selection operates on heritable varlation to drive adaptation of populations. In your response, Include:
1. The role of human-induced selective pressure
2. Why tusklessness increased over time
3. How does this exemplify the four factors of evolution?

Write in a 5th graders response and include evidence In one sentence each but provide the evidence

Answer 1

1) Role of human-induced selective pressure: Poachers hunted elephants with big tusks for ivory, so tusked elephants were more often killed and tuskless ones survived more, evidence: heavy hunting during the Mozambican Civil War (1977–1992) was followed by a big change in the population.

2) Why tusklessness increased over time: Because tuskless elephants survived and had babies more than tusked ones, the tuskless trait became more common, evidence: before the war most females had tusks (>90%) but afterward about half of the females in Gorongosa were tuskless (~50%).

3) How this shows the four factors of evolution:
- Natural selection: Poaching favored tuskless elephants that survived to reproduce, evidence: the rise in tuskless females after intense hunting.
- Genetic drift: The population got much smaller from hunting, so random changes in gene numbers could happen, evidence: heavy hunting caused a population bottleneck during the war.
- Gene flow: If elephants moved into or out of Gorongosa they could add or remove tusk genes, evidence: movement between groups mixes genes and can change trait frequencies.
- Mutation: New mutations can create new traits, but the quick rise in tusklessness was probably from genes already in the herd rather than new mutations, evidence: the change from >90% tusked to ~50% tuskless happened very fast, too fast for new mutations alone.