However a recent study by Karpagam Chelliah and Raman Sukumar of elephants at Kaziranga National Park, India, puts a wrinkle on this common… As the population has rebounded, a large portion of females remain without tusks. An increase in females without tusks has also been seen in Zambia, Tanzania and Uganda in recent years. It is unknown how many elephants survive in African, many herds are protected in preserved areas, like Gorongosa National Park in Mozambique. Elephants use tusks as tools for foraging, digging, breaking branches, stripping bark, and moving things around. For a start, male & female African elephants (Loxodonta africana) differ in tusk development. Take the case of the tuskless elephant. In 1919, the government hired Major P. J. Pretorius, the “great white hunter,” to eliminate the elephants in the area. Tusks start to grow after baby elephants lose their primary teeth during the first year of their lives. The tusks of elephants are lateral incisors, located on either side of their two front teeth. How are the elephants at Gorongosa National Park differ from other elephant populations? 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. Tusks are simply elongated, continuously growing front teeth that protrude beyond the mouth of mammal species such as elephants, walruses, warthogs, and narwhals. Currently, there are more than 600 elephants in the park, a real success story for conservation efforts. With the extra use, the master tusk develops a groove over time. About 2 to 6% of the female elephants are typically tuskless. 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. ... Addo’s rangers tend to get emotional about their elephants. A report from Nautilus report suggests a growing number of female elephants are tuskless, with links to the ivory trade. Although scientists have not worked out … ©Bureau of Economic Geology 2017. But with the hunting pressure off, experts think natural selection may again favor animals with tusks—and both groups may eventually become tusked again. Tusklessness is an (inherited/acquired) trait. [POOLE:] It ends up with a higher proportion of tuskless animals who then reproduce, and tend to produce tuskless offspring. WHY do males retain their tusks, when 50% of females lost them. 10. What percentage of females are typically tuskless in an elephant population less affected by poaching? The tusks are about one-fifth smaller in males, and more than one-third smaller in females. Today, the Gorongosa population includes about 800 individual elephants in 24 families. “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. By 1931, only 11 elephants remained in the region, and half of the 8 female survivors were tuskless. Tuskless females tend to have _____ (tusked/tuskless) offspring. Individuals in a population differ in some trait. Use the theory of evolution to explain the observation that there are no tuskless males in the park. Adopted a LibreTexts for your class? Mr. Tuskless females tend to have (tusked/tuskless) offspring. 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. Some individuals with a trait are more likely to survive and reproduce than those without the trait. Protecting the tuskless females seems to be the reason bull elephants often come first to the water holes in Addo. [ "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 1978, the elephant is listed as threatened under the United States’ Endangered Species Act. Going tuskless Smaller tusks are not the only genetic consequence faced by elephant populations in Africa (and Asia) due to heavy poaching. The longest African elephant tusk ever recorded was 11.5 ft (3.5 m) long. your username. 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. Rhinos are known to easily dispatch of hippos, lions, and hyenas in the wild, but an elephant is a totally different matter. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Again, elephants with tusks were killed, and by the end of the war, half the females were tuskless. Because poaching takes out elephants with tusks, more tuskless females survive. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. But the reason why males, so far at least, have not evolved to be tuskless is not clear. Log into your account. Tusks continue to grow longer and thicker throughout their lives. With the passing of time and generations, the proportion of tusked individuals in the population will probably increase, slowly reverting back toward baseline levels. The Gorongosa elephants still exhibit dramatic behaviors that indicate they remember the horrors of the war—they have a heightened fear of people. Of the less than 200 survivors, over 50 percent of the females – 25 years or older – had no tusks. Older female elephants — spared because they had no tusks — then passed the tuskless gene down to their daughters. Historically, 2–4 percent of unstressed African elephant females are tuskless; tusks are an inherited genetic trait. Males, whose tusks tend to be larger than females’, also use their tusks to battle one another. Most African elephants have tusks, but some — about 2% to 6% of females and even fewer males — never grow them. The past century has seen a larger proportion of tuskless female African elephants develop in some areas. In the late 1800’s, farmers started settling in the area. What would probably happen to a male elephant that doesn’t have tusks? Tusklessness is being genetically favored — … 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. In Asian elephants, females do not have tusks and males can be either tusked or tuskless (called “makhnas”). While almost all male African elephants have tusks, around 2 to 6 percent of females live life with none whatsoever. 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. About 150 of these are independent adult males. But a small percentage of elephants are born without these teeth and never develop tusks. your password The trait is inherited (passed from parents to offspring). The tusks of males weigh up to seven times those of similarly aged females. 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 … When compared to the elephant populations across Africa, the frequency of tuskless elephants is only 6%. That founding population of 11 comprised 8 females & 3 males, but only one adult male (which had tusks) bred with the females. Tuskless females tend to have _____ (tusked/tuskless) offspring. Elephant specialists that study the elephants in this preserved area have collected data on the herds in the park. This drives the illegal trade of ivory. In 1919, the South African government brought trophy hunters to the East Cape to exterminate elephants that were eating crops and trampling farms. (This suggests that the genetic contol of tusk development must be quite complex.) Those spectacularly curved incisors … 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. WHY do males retain their tusks, when 50% of females lost them. Tusks are used as weapons against potential predators. So a population “ends up with a higher proportion of tuskless animals who then reproduce and tend to produce tuskless offspring,” she says. However, 33 percent of younger females are now born without tusks in … We often think that evolution takes thousands of years. 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. 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. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Legal. About 35 percent of females older than 25 are tuskless, she says. It's long been thought that tusks must confer an advantage in competitions between males for dominance and mating rights. Proportion of tuskless subadult females in relation to adult females recorded in 15 populations. In 1919 and 1920, he killed 114 elephants. Smaller tusks are not the only genetic consequence faced by elephant populations in Africa (and Asia) due to heavy poaching. Over several decades, researchers have documented an increase in the percentage of complete tuskless males and females in a number of elephant populations. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. Like humans, a small percentage of elephants are born without their lateral incisors. EarthDate is a production of the Bureau of Economic Geology at the University of Texas at Austin. The frequency of the trait that helps individuals survive or leave more offspring will increase in the population over time. Click here to let us know! As Europeans began to explore the continent, demand for ivory increased. 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. 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. Hence, it is not surprising that the park’s tuskless elephant population has grown substantially. Going tuskless. [NARRATOR:] Surveys conducted by Poole and colleagues indicated that 33% of females 10 to 20 years old are tuskless. The Evolutionary path of some giant African elephants develop in some cases, evolution may be shifted or by... 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