Although evolution is generally considered to be a process that can only be observed over extremely long time scales, it is sometimes possible to catch a glimpse of evolution at work today. Famously, naturalists in the United Kingdom were able to observe the evolution of darker coloration in the peppered moth during the Industrial Revolution. The burning of massive quantities of coal released ash and soot, which remained in the atmosphere and settled onto surfaces like trees. Consequently, darker-colored moths became less conspicuous to predators and had better success passing their genes onto later generations.
Similar observations have been made throughout the animal kingdom, especially among smaller organisms that have shorter lifespans. However, an interesting study was recently published in Science that demonstrated that pressure from humans has produced evolutionary changes in African elephants that we can see today.
Focusing on the population of elephants in Gorongosa National Park in Mozambique, researchers looked at the effects of intense pressure from poaching and the resulting drop in the elephant population. Poachers target the elephants for the highly sought after ivory their tusks can provide. However, the researchers noted that there has been an increase in the number of females born without tusks. Their investigation determined that this trait is sex linked and that carriers of the specific genes that generated a tuskless phenotype are less likely to become victims of poaching.
Poaching is a major threat to numerous species around the world. However, the closer we examine the issue of poaching, the better we understand the related harms that it can inflict. As these researchers discovered, even if poachers do not drive a species into extinction, they can leave long-lasting evidence of their actions.
Click here for the Japanese version.