Figure 1: A herd of tuskless African elephants in the savannahs of Mozambique
Source Credit: National Geographic (LINK)
Evolution is often thought to be a gradual, lengthy process that can only be recorded over millions of years. But case studies like those of African elephants demonstrate that external stressors can cause rapid changes in a population’s gene pool, and that consequences can be deadly.
The African elephant is among the most trafficked animals in the world. The majestic mammal is a common target of poaching due to its ivory tusks,a valuable but scarce resource driving a profitable black market. Scientists are now discovering troubling repercussions of the extensive ivory trade, which seemed almost ubiquitous in the 20th century before protective policies were enforced.
The elephants that roam Mozambique’s Gorongosa National Park are no exception. During the country’s civil war that lasted from 1977 to 1992, there was a mass killing of elephants with tusks, which, paired with the sparing of naturally tuskless elephants, increased the number of elephants born without the gene for tusks. An estimated 20% of female elephants were tuskless prior to the war, as opposed to over 50% of today’s being naturally tuskless. While this is already a major concern as tusks are vital tools to carry out various tasks in the everyday life of an elephant, the study uncovered even more dire consequences of the genetic shift.
It was noticed that there was not a trace of tuskless males. The researchers quickly devised a conjecture, one that they hoped was incorrect. Sequencing the genome of the tuskless elephants, they concluded that the absence of tusks was a dominant trait carried by females. However, the genes become lethal when passed onto males, causing incomplete development and in turn, death.
The team identified the involved gene to be AMELX, an important code in the building of teeth found exclusively on the X chromosome. The gene is directly adjacent to genes that, when missing, can cause death in males.
Scientists hope that as they continue researching this genetic phenomenon, they can bring more detailed information to light. How exactly does the small change in the African elephants’ genomes induce persistent miscarriages? Will tuskless elephants be able to modify their lifestyle to compensate for their missing tusks? What does the dwindling male population signify for the long-term future of the species? While these questions remain in the dark, there is no doubt that their answers are needed, and fast.
Q&A:
Anna: Why did the researchers (mentioned in paragraph 4) hope that their conjecture was incorrect?
They understood that if the tuskless gene truly did cause mortality in male elephants, its consequences could cascade into something much more devastating. Their guess was unfortunately correct.
Sally: What kind of difficulties do tuskless elephants face? And why did the civil war spare more tuskless elephants than those with the tusks?
Elephants are among the most trafficked animals in the world, and much of that has to do with their tusks. Their ivory tusks hold a lot of cultural and monetary value in the black market, which is why they were commonly targeted during the country’s civil war.
Jennah: Other than African elephants, are there any other mammals that are experiencing a similar peril regarding dramatic gene pool change?
While I haven’t done research on any other species, I would expect that there are somewhat similar situations persisting around the world. I think it’s safe to say that humanity needs to take a step back and really work to reverse the widespread harm it has brought upon wildlife.
Hannah: Do male elephants that receive this gene immediately die after birth, as you said it could be lethal, or do they survive a few years until dying at an early age?
The gene itself is lethal to male elephants, even killing some prior to birth. It could, however, cause a more subtle increase in mortality for female elephants that have difficulty navigating their environment without tusks.
Works Cited
Maron, Dina Fine. “Under Poaching Pressure, Elephants Are Evolving to Lose Their Tusks.” Animals, National Geographic, 3 May 2021, https://www.nationalgeographic.com/animals/article/wildlife-watch-news-tuskless-elephants-behavior-change.
Press, The Associated. “Elephants Have Evolved to Be Tuskless Because of Ivory Poaching, a Study Finds.” NPR, NPR, 22 Oct. 2021, https://www.npr.org/2021/10/22/1048336907/elephants-tuskless-ivory-poaching-africa.
Preston, Elizabeth. “Tuskless Elephants Escape Poachers, but May Evolve New Problems.” The New York Times, The New York Times, 21 Oct. 2021, https://www.nytimes.com/2021/10/21/science/tuskless-elephants-evolution.html.
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