Final answer:
The reduction in tusk size among male African elephants is an example of artificial selection caused by extensive hunting for their ivory tusks.
Step-by-step explanation:
The significant reduction in tusk size among male African elephants from the early 1900s to today stands as a striking example of artificial selection driven by human activities. This phenomenon is primarily a consequence of intense hunting pressure targeting elephants with larger tusks, driven by the high demand for ivory. The selective removal of males with larger tusks has led to a shift in the population's genetics, favoring elephants with smaller tusks.
Artificial selection, in this context, results from human-driven processes that act as a powerful force shaping the evolution of a species. The economic value placed on ivory has directly influenced the genetic composition of elephant populations. As hunters target elephants with larger tusks for their valuable ivory, those individuals are effectively removed from the breeding pool. This selective removal has resulted in a higher prevalence of genes associated with smaller tusks being passed on to subsequent generations.
Over time, this artificial selection has led to a noticeable phenotypic change in male African elephants, with a common trend towards shorter tusks in adulthood. The evolution of smaller-tusked elephants is a direct outcome of the selective breeding imposed by human activities.
This example underscores the profound impact human actions can have on the evolutionary trajectories of species. As demand for ivory persists, the consequences of artificial selection continue to shape the characteristics of elephant populations, reflecting the intricate interplay between human activities and the natural world.