Many people think of evolution as a slow process of incremental changes that take ages to form a noticeable difference. In actuality, this is not always the case, even for large animals.
It turns out that the African savannah elephant is a fascinating (albeit rather sad) example of fast evolution in large animals. Researchers studied the impact of ivory poaching on these magnificent animals and uncovered some interesting findings.
Image Credit: Fotogrin via Shutterstock / HDR tune by Universal-Sci
Evolution can be explained as the gradual change in populations through the inheritance of traits and characteristics with their variation and natural selection.
Through genes, an organism inherits the hereditary properties and, therefore, characteristics of its parent(s). Mutations (changes in the genome) can result in new traits arising in an organism's offspring. If a new trait offers an advantage, this organism will have a greater chance of survival and producing offspring.
The above-mentioned mechanism is known as natural selection and results in traits that offer advantages becoming more common in a population.
An evolutionary advantage against poaching
In 2021, biologists discovered a remarkable number of tuskless female elephants in an elephant population in Gorongosa National Park in Mozambique. From this, they conclude that the species has adapted in a short time in such a way that the tusks no longer pose a threat to their survival.
Large tusks can put elephants at a severe evolutionary disadvantage at some locations in Africa - Image Credit: Michael Zech Fotografie via Shutterstock / HDR tune by Universal-Sci
For decades, elephants have been killed for their ivory tusks, which generate a lot of money through illegal trade. For example, during the civil war in Mozambique, from 1977 to 1992, elephants were hunted en masse. The proceeds from the ivory were used to buy weapons and finance the war.
Poaching resulted in a drastic decrease in the elephant population. However, elephants that had no tusks survived. According to researchers, this was a driver for the proliferation of tuskless females with mutations in two particular tooth genes.
Under normal circumstances, it takes many generations for an animal species to adapt to changes, but under these extreme conditions, it occurred very quickly. The prompt decline of tusked elephants changed the selection of characteristics in the population in just two decades, leaving behind a larger population of tuskless elephants.
Why are only female elephants tuskless?
The research team also found an explanation for the fact that only the females have no tusks. It is caused by a genetic mutation on the X chromosome. Females have two of those chromosomes, whereas males only possess one. The mutation that causes tusklessness is lethal to males in the embryonic stage.
Tusks serve a purpose
Evolutionary biologist Shane Campbell-Staton explains that tusks are not just ornamental but serve a purpose. For example, elephants use their tusks to defend their territory, strip tree bark and dig in search of roots and water.
Savanna in National Park Gorongosa - (Image Credit: nicolasdecorte via Shutterstock / HDR tune by Universal-Sci)
If the dangers of poaching diminish, tusks may eventually return. However, as of now, African elephants are under serious threat to their survival due to poaching and habitat loss.
All in all, according to Campbell-Station, poaching is changing the course of evolution in Gorongosa elephants and may have substantial effects on the ecosystem, given their considerable impact on their surroundings.
Sources and further reading:
Ivory poaching and the rapid evolution of tusklessness in African elephants - (Science)
In evolution, the need for sleep may have arisen earlier than the acquisition of a brain - (Universal-Sci)
Humans now drive evolution on Earth, both creating and destroying species - (Universal-Sci)
Human evolution is still happening – possibly faster than ever - (Universal-Sci)
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