APEX BIOLOGY - QTR. 3Submit only this page for grading.Packet #10 of 14March 1-5, 2021Barton, Somosa, Yonnie7Artificial SelectionUsing selective breeding, humans can cause alleles in populations to change.Natural selection occurs in response to environmental pressures and results in changes in species over longperiods of time. A human strategy for speeding up the appearance of desired traits is called artificial selection.In artificial selection (or selective breeding), humans select certain animals or plants to breed because ofspecific traits they possess. The goal is to increase the frequency of these traits in the population, whiledecreasing the appearance of undesired traits.Artificial selection has been applied to many different plant and animal species. In fact, most of today'sdomestic animals, like pets and livestock, are the direct result of artificial selection.Human Impact on EvolutionHumans have an impact on the evolution of species.There are many mechanisms that can cause allele frequencies to change over time. Understanding thesemechanisms helps us better understand how we affect other species on Earth.For example, overapplication of pesticides has led to some plant species evolving resistance to pesticides.These plants now grow in a way that cannot be controlled, destroying valuable forests.Overuse of antibiotics has caused some harmful bacteria to evolve resistance to antibiotics, making thesebacteria even more difficult to treat.Mass ExtinctionMass extinction decreases biodiversity.A mass extinction is an event in which 60 percent of the organisms present on Earth become extinct. Scientistbelieve that there have been five mass extinctions since life first formed on Earth. After each mass extinction,the biodiversity of the planet greatly decreased.
