Human induced evolution of species – UPSC GS3

Example of Human induced evolution:
  • Tuskless Elephants: In Mozambique, past hunting pressure has led to an increase of naturally tuskless elephants. According to researchers, decades of poaching have made tusklessness relatively advantageous from an evolutionary standpoint in Gorongosa. This has resulted in the proliferation of tuskless females with mutations in two tooth genes.
  • Decrease in horn size of bighorn sheep: A rapid decrease in horn size of bighorn sheep, a prime target for trophy hunting in North America, has been noticed.
  • Smaller fishes: High harvesting rates of larger fish have resulted in significant decreases in body size and earlier age of maturation in several species like Atlantic cod, Atlantic salmon
  • Smaller red kangaroos: In the case of the red kangaroo, hunters target the larger individuals in a group, and there is evidence that the average size has declined.
What are the negative consequences of it?
  • Extinction and loss of genetic variation: Humans target animals with certain desirable physical properties or phenotypes. It results in increased mortality among animals with desirable phenotypes. Consequently, those features start to decrease in frequency.
  • Difficulty in carrying routine activities to animals: For example, Tusks are not just ornamental. They serve a purpose”, elephants use tusks to dig for water and strip tree bark for food. With the loss of useful traits, they might be unable to perform their basic needs.
  • Increase in drug-resistant superbugs: Antibiotics impose extreme selection pressure on microbes, fungus and parasites. As a consequence, the microbes evolve to resist any drugs. For example, DDT-resistant mosquitoes. When the use of DDT as an insecticide started in the 1940s, the DDT -resistant ability of Mosquitoes increased. Now mosquitoes are largely immune to the chemical.
What is the way forward?
  • The application of genomic technology can minimise the risk of harmful genetic changes caused by the exploitation of wild species to some extent.
  • Until then, humans  must avoid levels of exploitation that require several years of evolutionary recovery.
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