Going tuskless Smaller tusks are not the only genetic consequence faced by elephant populations in Africa (and Asia) due to heavy poaching. By 1979, there were only 1.3 million elephants left. Mr. Click here to let us know! Fortunately, public opinion forced a change of heart and a preserve was established to protect the elephants. Can a rhino kill an elephant? About 35 percent of females older than 25 are tuskless, she says. Most males have tusks, while many females are tuskless, or have small tusks. In fact, studies have documented that even female elephants with no tusks have increased from 10.5% to 38.2% between 1969 and 1989 – during the time when poaching was heaviest. Use the theory of evolution to explain the observation that there are no tuskless males in the park. “Among females then, the poachers were preferentially killing animals with tusks and leaving tuskless ones to survive, so they were breeding and producing more tuskless offspring,” Poole said. But in some cases, evolution may be shifted or accelerated by human intervention in the natural world. Males, whose tusks tend to be larger than females’, also use their tusks to battle one another. Those spectacularly curved incisors … We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Diet Elephants eat roots, grasses, fruit, and bark, and they eat a lot of these things. The tusks are about one-fifth smaller in males, and more than one-third smaller in females. Currently, there are more than 600 elephants in the park, a real success story for conservation efforts. Log into your account. Complete the VIDA Chart - The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Historically, 2–4 percent of unstressed African elephant females are tuskless; tusks are an inherited genetic trait. Males use tusks to vie with other males for mates. Selection for Tuskless Elephants | hhmi BioInteractive, How an Elephant Loses Its Tusks: A Lesson in (Un)Natural Selection | National Geographic, Going Tuskless | African Wildlife Federation, Natural & Cultural History | Addo Elephant National Park, Contributors: Dr. Joyce Poole and Petter Granli (ElephantVoices), Juli Hennings, Harry Lynch. Most African elephants have tusks. With the extra use, the master tusk develops a groove over time. Tusks are simply elongated, continuously growing front teeth that protrude beyond the mouth of mammal species such as elephants, walruses, warthogs, and narwhals. your password g. Tusklessness is an (inherited/acquired) trait. Did human activity change the evolutionary path of some giant African elephants? Tuskless females tend to have (tusked/tuskless) offspring. [NARRATOR:] Poaching selected for tuskless females. The Gorongosa elephants still exhibit dramatic behaviors that indicate they remember the horrors of the war—they have a heightened fear of people. Most obvious, though, is the high proportion of tuskless elephants. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. By 1931, only 11 elephants remained in the region, and half of the 8 female survivors were tuskless. Elephant tusks are important for obtaining food and water, and essential to male elephants for competing for mates, so one might expect strong natural selection for having tusks. In South Africa’s Eastern Cape, northeast of the city of Port Elizabeth, the Addo Elephant National Park is home to a unique population of elephants with a sad past but an amazing conservation story. Welcome! Fewer African elephant males are tuskless because successful competition for females is strongly dependent on tusks. This limited the trade of some ivory. Illegal hunting of elephants, or poaching, occurs at alarming levels. Tuskless females tend to have _____ (tusked/tuskless) offspring. What happened in Mozambique between 1977 and 1992? For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. (This suggests that the genetic contol of tusk development must be quite complex.) The heaviest tusk recorded weighed almost 265 lbs (120 kg)! In other words, the Addo elephants have been through a substantial population bottleneck. WHY do males retain their tusks, when 50% of females lost them. WHY do males retain their tusks, when 50% of females lost them. __________________. ©Bureau of Economic Geology 2017. All rights reserved. Selection for tuskless elephants Instead of natural selection, this was human selection. Variations can be physical features, behaviors, bodily functions, or resistance to disease. Use the theory of evolution to explain the observation that there are no tuskless males in the park. Legal. What percentage of females are typically tuskless in an elephant population less affected by poaching? Elephant specialists that study the elephants in this preserved area have collected data on the herds in the park. Bull Asian elephants come in two forms: tusk, and tuskless (this is termed dimorphism). Despite the bans, there is still a demand for ivory in countries like Japan and China. Proportion of tuskless subadult females in relation to adult females recorded in 15 populations. Developing an Explanation for Tuskless Elephants INTRODUCTION Most African elephants have tusks, but typically about 6% of females in a population will never … About 2 to 6% of the female elephants are typically tuskless. In 1919, the government hired Major P. J. Pretorius, the “great white hunter,” to eliminate the elephants in the area. A similar thing happened in Mozambique. In 1919 and 1920, he killed 114 elephants. As Europeans began to explore the continent, demand for ivory increased. Genetically, tusklessness only occurs in 2-4% of female African elephants, but in Mozambique’s war-torn Gorongosa National Park, over 50% of all elderly females have … Tusklessness is an ___________________________ (inherited/acquired) trait. Complete the following table. When compared to the elephant populations across Africa, the frequencyof tuskless elephants is only 6%. Elephant slaughter increased in the 1950s, where it is estimated that 250 elephants were killed per day. What is unusual about the elephant populations found in Gorongosa now? Hence, it is not surprising that the park’s tuskless elephant population has grown substantially. But the reason why males, so far at least, have not evolved to be tuskless is not clear. In Mozambique’s Gorongosa National Park, one-third of younger female elephants, and half of the older ones, have no tusks. Nearly all male elephants and most females have tusks. A report from Nautilus report suggests a growing number of female elephants are tuskless, with links to the ivory trade. A ban on the international trade of ivory goes into effect in 1990, though the population of elephants is now fewer than a million. These are just elongated lateral incisors that grow outward once the elephant loses its baby teeth. Most African elephants have tusks, but some — about 2% to 6% of females and even fewer males — never grow them. What percentage of females are typically tuskless in an elephant population less affected by poaching? However a recent study by Karpagam Chelliah and Raman Sukumar of elephants at Kaziranga National Park, India, puts a wrinkle on this common… Tusklessness is being genetically favored — … Synopsis: Evolutionary change generally involves long time frames of Earth history. (Our favorite tusks? For a start, male & female African elephants (Loxodonta africana) differ in tusk development. As in Gorongosa, the numbers are highest among older females. During a 15-year civil war, soldiers poached elephants for their meat to feed the troops and for their ivory to sell to buy more weapons. Elephants tend to favor one tusk—the master tusk—over the other, similar to being right- or left-handed. 1. While almost all male African elephants have tusks, around 2 to 6 percent of females live life with none whatsoever. We often think that evolution takes thousands of years. The longest African elephant tusk ever recorded was 11.5 ft (3.5 m) long. Elephants with more ivory were more valuable targets. [POOLE:] It ends up with a higher proportion of tuskless animals who then reproduce, and tend to produce tuskless offspring. “Females who are tuskless are more likely to produce tuskless offspring,” she said. Tusks start to grow after baby elephants lose their primary teeth during the first year of their lives. [NARRATOR:] Surveys conducted by Poole and colleagues indicated that 33% of females 10 to 20 years old are tuskless. Again, elephants with tusks were killed, and by the end of the war, half the females were tuskless. Although scientists have not worked out … The groups, which do not include bulls, are led by the (usually) oldest cow, known as the matriarch. Tuskless females tend to have (tusked/ tuskless) offspring. In Gorongosa National Park, Mozambique, however, about 33% of young females are tuskless.What are tusks? With the passing of time and generations, the proportion of tusked individuals in the population will probably increase, slowly reverting back toward baseline levels. In 1978, the elephant is listed as threatened under the United States’ Endangered Species Act. So a population “ends up with a higher proportion of tuskless animals who then reproduce and tend to produce tuskless offspring,” she says. The past century has seen a larger proportion of tuskless female African elephants develop in some areas. Why do bans on ivory trade not stop elephants from being slaughtered? The tuskless matriarchs had tuskless offspring, and today nearly all female elephants in the park lack tusks. Take the case of the tuskless elephant. Because poaching takes out elephants with tusks, more tuskless females survive. However, 33 percent of younger females are now born without tusks in … When compared to the elephant populations across Africa, the frequency of tuskless elephants is only 6%. What would probably happen to a male elephant that doesn’t have tusks? your username. Have questions or comments? EarthDate is a production of the Bureau of Economic Geology at the University of Texas at Austin. Furthermore, among elephants over 25 years old the population is very skewed toward females, due to the fact that male elephants have much larger tusks and are, therefore, preferentially killed by poachers. This is unlike the African elephant species, in which all individuals have tusks. These are just elongated lateral incisors that grow outward once the elephant loses its baby teeth. But tusks are also tools for gathering food, digging for water and fending off predators, so cows need them as well. Tusklessness is an (inherited/acquired) trait. The tusks of males weigh up to seven times those of similarly aged females. Use the theory of evolution to explain the observation that there are no tuskless males in the park. Tuskless females tend to have _____ (tusked/tuskless) offspring. The males retained their tusks. That founding population of 11 comprised 8 females & 3 males, but only one adult male (which had tusks) bred with the females. But in rare cases where humans impact small populations, adaptation can work much faster. Still, ivory trade continued across the world. They noticed that while all the males have tusks, about 50% of the females in the park that are over the age of 20 years do not have tusks. During the 15 years of the Mozambican Civil War (1977–1992), Gorongosa elephants were ruthlessly hunted and poached by soldiers—both for meat to feed troops and for ivory to sell to fund weapons purchases. Some individuals with a trait are more likely to survive and reproduce than those without the trait. Over several decades, researchers have documented an increase in the percentage of complete tuskless males and females in a number of elephant populations. It is unknown how many elephants survive in African, many herds are protected in preserved areas, like Gorongosa National Park in Mozambique. 10. The tusks of elephants are lateral incisors, located on either side of their two front teeth. No tuskless males have been found. As the population has rebounded, a large portion of females remain without tusks. That year, the Addo Elephant National Park was established to provide sanctuary for these elephants as well as other African animals. Discussion Ideas. It was used to make combs, pool balls, knick-knacks, and even piano keys. The variation comes from random mutations and the recombination during sexual reproduction. Younger females who are now 15–25 years old were not around during the war, but almost a third of them are tuskless, the result of a decrease in the number of their parents with the genes for tusks. [ "article:topic", "showtoc:no", "license:ccbyncsa", "authorname:smuskopf" ], https://bio.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fbio.libretexts.org%2FLearning_Objects%2FWorksheets%2FBook%253A_The_Biology_Corner_(Worksheets)%2FEvolution%2FAfrican_Elephant_-_Change_Over_Time, Applying Hardy-Weinberg to Rock Pocket Mouse Field Data, information contact us at info@libretexts.org, status page at https://status.libretexts.org. In the late 1800’s, farmers started settling in the area. This drives the illegal trade of ivory. In Asian elephants, females do not have tusks and males can be either tusked or tuskless (called “makhnas”). Rhinos are known to easily dispatch of hippos, lions, and hyenas in the wild, but an elephant is a totally different matter. Smaller tusks are not the only genetic consequence faced by elephant populations in Africa (and Asia) due to heavy poaching. And among elephants ages five to 25, 13 percent of females are tuskless. Going tuskless. Of the surviving elephants that were adults during the war, most are female, and over half of these are tuskless, evidence of the preferential poaching of males and older tusked females. This story also brings to mind the sad tale of Addo Elephant National Park in South Africa, where 98 percent of female elephants don’t have tusks. Tuskless females tend to have _____ (tusked/tuskless) offspring. WHY do males retain their tusks, when 50% of females lost them. How are the elephants at Gorongosa National Park differ from other elephant populations? Humans appear to have caused this shift in elephant evolution. How do countries in Africa protect elephant herds? Of all the animals on this list, the rhino stands the best chance at actually defeating an elephant. By 1913, the African elephant population had dropped to an estimated 10 million. ... Addo’s rangers tend to get emotional about their elephants. Like humans, a small percentage of elephants are born without their lateral incisors. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. Elephants use tusks as tools for foraging, digging, breaking branches, stripping bark, and moving things around. As a result of both the proportion of tuskless elephants in the surviving population and inbreeding, 98 percent of female elephants in the park were tuskless by 2000. In 1919, the South African government brought trophy hunters to the East Cape to exterminate elephants that were eating crops and trampling farms. An increase in baby elephants born without tusks has conservationists asking if the trend is an evolutionary response to ivory poaching. Why are elephants killed in Africa? Selection depends on the environment. Females go tuskless, not males Generally, the tusks of a male elephant are bigger and heavier than those of a female, so they tend to get poached first. 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