Natural, Relaxed, and Artificial Selection

1. Natural, Relaxed, and Artificial Selection Hasan Mahmud

2. Natural Selection • Is the basis of the other types of selection • Competition Variation • Heriatble Difference in survival • Relaxed and Artificial Selection are simply natural selection under different • Each of the two change different parameters and

3. Relaxed Selection • Is a selective phenomena that occurs when selective pressures are either elimatedor dramatically reduced • Are many new cases as society becomes more and more complex

4. Examples of Relaxed Selection • When selective pressures are reduced or eliminated they can be biotic or abiotic • Biotic examples • Predation elimination • Elimination of pathogen • Abiotic examples • Changes in light and temperature and water • Changes soil and mineral composition

5. Modern Medicine • Modern Medicine • Elimination of Many diseases that used to be lethal • Compensation for Chronic and Genetic Diseases • Helps with common health problems • Sight problems • Hearing problems

6. Other Examples • Malaria resistance • Without the pressure of possible infection there is no heterozygous advantage • Galapagos • Without the presence of predators and the abundance of food many animals in the Galapagos have become much larger than their main land counterparts

7. Problems with Relaxed Selection • Many of the problems with relaxed selection only come into play when those pressures are re-introduced • While some times the organism has come up with new way to deal with the pressures other times can be very costly to the pouplation

8. Artificial Selection • Usually through intention human involvement the selection of non-essential traits in a population • Many times the means through which selection is done is harmful to the population • Artificial selection is done for two purposes • To increase production such as milk, eggs, meat • Enhancement of desired traits e.x dogs horses

9. Misconception of Artificial Selection • Artificial Selection does and cannot create new traits • Uses recessive traits or enhances existing traits to unusual expression • Many of the artificially created species can still breed with ancestral species

11. Problems with Artificial Selection • While some examples of artificial selection are not intentional • Initial domestication of Animals • Initial enhancement of crops • Many examples of Artificial Selection are done through in breeding • Purebred dogs • Race horses

12. Connections • Artificial, Relaxed, and Natural Selection are not separate and different forces • Each is just a subset of the larger evolutionary force • Artificial selection is taken to the extreme where there is a desired goal • Relaxed selection is the absence of pressure and the evolutionary pathways that forms

13. Works Cited • http://images.google.com/imghp?gbv=2&um=1&hl=en&btnG=Search+Images • 1 Bryant, Edwin H. "Fitness Decline under Relaxed Selection in Captive Populations." Conservation Biology 13 (2001): 665-69. • 2 "Evolution and Natural Selection." Evolution and Natural Selection. 10 Oct. 2008. Universtiy of Michigan. 5 Nov. 2008 <http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html>. • 3 Foster, Susan A., and John A. Endler. "Effects of Relaxed Selection Evolutionary Behavior." Geographic Variation in Behavior. • 4 Gayle, Lisa. "Genetic Disorders." Encyclopedia of Childhood and Adolescence 42 (1998). • 5 Guyon, Isabelle. "An introduction to variable and feature selection." The Journal of Machine Learning Research 3 (2003): 1157-182. • 6 Innan, Hideki. "Pattern of polymorphism after strong artificial selection in a domestication event." Biological Science 109 (2004): 106667-0672. • 7 "Malaria and the Red Cell." 02 Apr. 2002. Information center for sickle and thalessis Disease. 28 Nov. 2008 <http://sickle.bwh.harvard.edu/index.html>. • 8 Robertson, A. "A Theory of Limits in Artifical Selection." Proceedings of the Royal Society of London. Series B, Biological Sciences 153 (2000): 234-49.