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No Longer Long in the Tooth

Tusklessness in African Elephants

By Alison J. Albee, J. Megan Woltz, Taylor Kemp, Emma Mays, Tylor M. Miller, Eric Fisher, Amanda Loutzenhiser

No Longer Long in the Tooth



This case study focuses on the characteristic of tusklessness in the African elephant population of Gorongosa National Park, Mozambique, to examine molecular and macroscopic aspects of evolution. Students are introduced to the plight of African elephants and the importance of tusks (modified incisor teeth) for elephant fitness and for their role as a keystone species. They learn that intense poaching of African elephants has caused an increase in tuskless females, despite the fitness benefit that tusks otherwise provide. To understand the gene-to-protein-to-phenotype connection at the molecular level, students explore the effect of an X-chromosome deletion on protein production of a key gene in tooth formation. Using Punnett squares, students examine the X-chromosome deletion to develop an understanding for why tusklessness is found only in female and not male elephants. Lastly, students connect phenotype (tusked or tuskless) to fitness in the presence and absence of heavy poaching. This case is ideally suited for upper-level biology students to thoroughly connect gene mutation to fitness during evolution.


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  • Understand the environmental cause of decreased African elephant populations.
  • Explain how the fitness impacts of a mutation depend on the environment experienced by the population.
  • Explain how a mutation can increase in frequency, and in particular how the mutation associated with tusklessness resulted in increased fitness in an African elephant population under specific environmental conditions.
  • Recall that the AMELX gene encodes the protein amelogenin that is required for tusk formation.
  • Connect how an X chromosomal deletion explains the lack of tuskless males.
  • Explain fitness as it relates to tusked and tuskless elephants in environments with and without poaching.


X chromosome; natural selection; tooth formation; genetics; gene dosage; chromosome deletion; hemizygous; fitness; evolution; keystone species; elephants; poaching; tusklessness; AMELX; amelogenin


Subject Headings

Cell Biology
Dental Medicine
Evolutionary Biology
Genetics / Heredity


Undergraduate upper division












Directed, Discussion, Interrupted



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