Discussion Ideas. Diet Elephants eat roots, grasses, fruit, and bark, and they eat a lot of these things. Tusklessness is an ___________________________ (inherited/acquired) trait. It is unknown how many elephants survive in African, many herds are protected in preserved areas, like Gorongosa National Park in Mozambique. Elephant specialists that study the elephants in this preserved area have collected data on the herds in the park. Elephants with more ivory were more valuable targets. As in Gorongosa, the numbers are highest among older females. 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. Their crops attracted elephants that raided and trampled fields, so farmers promoted hunting to reduce the damages. EarthDate is a production of the Bureau of Economic Geology at the University of Texas at Austin. Those spectacularly curved incisors … Early estimates of elephants on the continent of Africa suggest that there were as many as 26 million elephants living there in the 1500s. Like humans, a small percentage of elephants are born without their lateral incisors. Tusks are used as weapons against potential predators. “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. Still, ivory trade continued across the world. About 35 percent of females older than 25 are tuskless, she says. Although scientists have not worked out … What percentage of females are typically tuskless in an elephant population less affected by poaching? Females (cows) tend to live in family groups, which can consist of one female with her calves or several related females with offspring. A similar thing happened in Mozambique. What would probably happen to a male elephant that doesn’t have tusks? Elephants use tusks as tools for foraging, digging, breaking branches, stripping bark, and moving things around. [POOLE:] It ends up with a higher proportion of tuskless animals who then reproduce, and tend to produce tuskless offspring. In the late 1800’s, farmers started settling in the area. WHY do males retain their tusks, when 50% of females lost them. Smaller tusks are not the only genetic consequence faced by elephant populations in Africa (and Asia) due to heavy poaching. For a start, male & female African elephants (Loxodonta africana) differ in tusk development. By 1913, the African elephant population had dropped to an estimated 10 million. Hence, it is not surprising that the park’s tuskless elephant population has grown substantially. Going tuskless. Males use tusks to vie with other males for mates. The heaviest tusk recorded weighed almost 265 lbs (120 kg)! The Gorongosa elephants still exhibit dramatic behaviors that indicate they remember the horrors of the war—they have a heightened fear of people. That founding population of 11 comprised 8 females & 3 males, but only one adult male (which had tusks) bred with the females. Why do bans on ivory trade not stop elephants from being slaughtered? With the extra use, the master tusk develops a groove over time. What happened in Mozambique between 1977 and 1992? Did human activity change the evolutionary path of some giant African elephants? While almost all male African elephants have tusks, around 2 to 6 percent of females live life with none whatsoever. It was used to make combs, pool balls, knick-knacks, and even piano keys. [NARRATOR:] Poaching selected for tuskless females. 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. Individuals in a population differ in some trait. How are the elephants at Gorongosa National Park differ from other elephant populations? And among elephants ages five to 25, 13 percent of females are tuskless. But tusks are also tools for gathering food, digging for water and fending off predators, so cows need them as well. Today, the Gorongosa population includes about 800 individual elephants in 24 families. WHY do males retain their tusks, when 50% of females lost them. Tusks are simply elongated, continuously growing front teeth that protrude beyond the mouth of mammal species such as elephants, walruses, warthogs, and narwhals. In other words, the Addo elephants have been through a substantial population bottleneck. Tuskless females tend to have _____ (tusked/tuskless) offspring. Synopsis: Evolutionary change generally involves long time frames of Earth history. Variations can be physical features, behaviors, bodily functions, or resistance to disease. Over several decades, researchers have documented an increase in the percentage of tuskless males and females in a number of elephant populations. Tuskless females tend to have _____ (tusked/tuskless) offspring. Tusklessness is being genetically favored — … These are just elongated lateral incisors that grow outward once the elephant loses its baby teeth. The tusks of elephants are lateral incisors, located on either side of their two front teeth. 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. Males, whose tusks tend to be larger than females’, also use their tusks to battle one another. Tuskless females tend to have (tusked/ tuskless) offspring. 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. We often think that evolution takes thousands of years. The trait is inherited (passed from parents to offspring). Most African elephants have tusks, but some — about 2% to 6% of females and even fewer males — never grow them. Most African elephants have tusks. But a small percentage of elephants are born without these teeth and never develop tusks. Humans appear to have caused this shift in elephant evolution. 1. Log into your account. Currently, there are more than 600 elephants in the park, a real success story for conservation efforts. In 1919, the government hired Major P. J. Pretorius, the “great white hunter,” to eliminate the elephants in the area. ... Addo’s rangers tend to get emotional about their elephants. By 1979, there were only 1.3 million elephants left. 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. By 1931, only 11 elephants remained in the region, and half of the 8 female survivors were tuskless. Click here to let us know! Tusks continue to grow longer and thicker throughout their lives. As the population has rebounded, a large portion of females remain without tusks. “Females who are tuskless are more likely to produce tuskless offspring,” she said. The tusks are about one-fifth smaller in males, and more than one-third smaller in females. The tusks are about one-fifth smaller in males, and more than one-third smaller in females. Instead of natural selection, this was human selection. 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. Legal. Selection for tuskless elephants [NARRATOR:] Surveys conducted by Poole and colleagues indicated that 33% of females 10 to 20 years old are tuskless. But the reason why males, so far at least, have not evolved to be tuskless is not clear. Use the theory of evolution to explain the observation that there are no tuskless males in the park. Hunters have historically targeted elephants with the largest tusks because of the value of their ivory; males and older females have always been at higher risk. The longest African elephant tusk ever recorded was 11.5 ft (3.5 m) long. Most obvious, though, is the high proportion of tuskless elephants. 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. Historically, 2–4 percent of unstressed African elephant females are tuskless; tusks are an inherited genetic trait. Again, elephants with tusks were killed, and by the end of the war, half the females were tuskless. But in rare cases where humans impact small populations, adaptation can work much faster. When compared to the elephant populations across Africa, the frequencyof tuskless elephants is only 6%. Fortunately, public opinion forced a change of heart and a preserve was established to protect the elephants. It's long been thought that tusks must confer an advantage in competitions between males for dominance and mating rights. In 1919, the South African government brought trophy hunters to the East Cape to exterminate elephants that were eating crops and trampling farms. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. What percentage of females are typically tuskless in an elephant population less affected by poaching? These are just elongated lateral incisors that grow outward once the elephant loses its baby teeth. In Mozambique’s Gorongosa National Park, one-third of younger female elephants, and half of the older ones, have no tusks. Traits that are beneficial in one environment may not be beneficial in another. This limited the trade of some ivory. Complete the following table. Developing an Explanation for Tuskless Elephants INTRODUCTION Most African elephants have tusks, but typically about 6% of females in a population will never … The tusks of males weigh up to seven times those of similarly aged females. But with the hunting pressure off, experts think natural selection may again favor animals with tusks—and both groups may eventually become tusked again. Figure 1 shows the percent of tuskless female elephants expected in wild populations throughout the species' range, as well as the percent of tuskless females that survived the hunting between 1977 and 1992 (those over 25 years old) and the percent of female elephants born after 1992 without tusks in … Rhinos are known to easily dispatch of hippos, lions, and hyenas in the wild, but an elephant is a totally different matter. 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 … However, 33 percent of younger females are now born without tusks in … In Asian elephants, females do not have tusks and males can be either tusked or tuskless (called “makhnas”). No tuskless males have been found. Proportion of tuskless subadult females in relation to adult females recorded in 15 populations. When compared to the elephant populations across Africa, the frequency of tuskless elephants is only 6%. This is unlike the African elephant species, in which all individuals have tusks. Tuskless females tend to have _____ (tusked/tuskless) offspring. In 1978, the elephant is listed as threatened under the United States’ Endangered Species Act. The groups, which do not include bulls, are led by the (usually) oldest cow, known as the matriarch. Elephant slaughter increased in the 1950s, where it is estimated that 250 elephants were killed per day. Most males have tusks, while many females are tuskless, or have small tusks. Nearly all male elephants and most females have tusks. The variation comes from random mutations and the recombination during sexual reproduction. Fewer African elephant males are tuskless because successful competition for females is strongly dependent on tusks. Use the theory of evolution to explain the observation that there are no tuskless males in the park. 10. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Tuskless females tend to have (tusked/tuskless) offspring. g. Tusklessness is an (inherited/acquired) trait. Complete the VIDA Chart - The frequency of the trait that helps individuals survive or leave more offspring will increase in the population over time. 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. Use the theory of evolution to explain the observation that there are no tuskless males in the park. Tusks start to grow after baby elephants lose their primary teeth during the first year of their lives. Have questions or comments? About 150 of these are independent adult males. your username. (Our favorite tusks? This drives the illegal trade of ivory. Of all the animals on this list, the rhino stands the best chance at actually defeating an elephant. With the passing of time and generations, the proportion of tusked individuals in the population will probably increase, slowly reverting back toward baseline levels. [ "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 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. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. The tuskless matriarchs had tuskless offspring, and today nearly all female elephants in the park lack tusks. About 2 to 6% of the female elephants are typically tuskless. Of those 8 founding females, 4 (50%) were tuskless & 3 had at least one tusk, Whitehouse could find no details of the 8th. Farther to the northeast, at Gorongosa National Park in Mozambique, the elephant population suffered a more recent tragic history that has led to what some call “unnatural selection.”. An increase in females without tusks has also been seen in Zambia, Tanzania and Uganda in recent years. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. Older female elephants — spared because they had no tusks — then passed the tuskless gene down to their daughters. Tusklessness is an (inherited/acquired) trait. The males retained their tusks. The “unnatural selection” pressure of hunting and war creates circumstances in which tuskless elephants are more likely to survive, breed, and pass on the genes for missing lateral incisors in regions where intense hunting or poaching has occurred. 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. Going tuskless Smaller tusks are not the only genetic consequence faced by elephant populations in Africa (and Asia) due to heavy poaching. Adopted a LibreTexts for your class? Welcome! Elephants tend to favor one tusk—the master tusk—over the other, similar to being right- or left-handed. Can a rhino kill an elephant? Mr. Of the less than 200 survivors, over 50 percent of the females – 25 years or older – had no tusks. Despite the bans, there is still a demand for ivory in countries like Japan and China. In 1919 and 1920, he killed 114 elephants. Some individuals with a trait are more likely to survive and reproduce than those without the trait. All rights reserved. Even though they now live in a safe preserve, more than 25 years after the war they avoid being out in the open and at water sources during the day, and may attack or run hysterically from people. Over several decades, researchers have documented an increase in the percentage of complete tuskless males and females in a number of elephant populations. Why are elephants killed in Africa? Take the case of the tuskless elephant. 10. (This suggests that the genetic contol of tusk development must be quite complex.) How do countries in Africa protect elephant herds? Because poaching takes out elephants with tusks, more tuskless females survive. As Europeans began to explore the continent, demand for ivory increased. Protecting the tuskless females seems to be the reason bull elephants often come first to the water holes in Addo. your password WHY do males retain their tusks, when 50% of females lost them. ©Bureau of Economic Geology 2017. What is unusual about the elephant populations found in Gorongosa now? The past century has seen a larger proportion of tuskless female African elephants develop in some areas. 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. An increase in baby elephants born without tusks has conservationists asking if the trend is an evolutionary response to ivory poaching. 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. In Gorongosa National Park, Mozambique, however, about 33% of young females are tuskless.What are tusks? Bull Asian elephants come in two forms: tusk, and tuskless (this is termed dimorphism). 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. But a small percentage of elephants are born without these teeth and never develop tusks. A report from Nautilus report suggests a growing number of female elephants are tuskless, with links to the ivory trade. 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. By 1931, only eight females survived, and half were tuskless—perhaps because they made the least attractive trophies. __________________. So a population “ends up with a higher proportion of tuskless animals who then reproduce and tend to produce tuskless offspring,” she says. That year, the Addo Elephant National Park was established to provide sanctuary for these elephants as well as other African animals. Nearly all male elephants and most females have tusks. A ban on the international trade of ivory goes into effect in 1990, though the population of elephants is now fewer than a million. However a recent study by Karpagam Chelliah and Raman Sukumar of elephants at Kaziranga National Park, India, puts a wrinkle on this common… Selection depends on the environment. But in some cases, evolution may be shifted or accelerated by human intervention in the natural world. Illegal hunting of elephants, or poaching, occurs at alarming levels. 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