Natural Selection and its types
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Natural selection is a process whereby organisms better adapted to their environment tend to survive and produce more offspring. There are three main types of natural selection: directional selection favors one extreme of a trait, disruptive selection favors both extremes of a trait, and stabilizing selection favors intermediate forms of a trait. Examples of natural selection in action include the evolution of different beak shapes in Galapagos finches and the increase of melanism in moths due to pollution. Sexual selection is a form of natural selection resulting from competition or choice of mates.
Natural Selection and its types
- 2. Usman M.Phil Zoology Section B Topic Of Presentation NATURAL SELECTION AND ITS TYPES
- 3. Natural selection described by Charles Darwin. Basic and fundamental mechanism of the theory of evolution. The term was introduced in "On The Origin of Species," in 1859.
- 4. The Natural Selection is a process, by which organisms are better adapted to their environment tend to survive and produce more offspring. A Natural Selection is a process that results in the survival and reproductive success of individuals or groups best adjusted to their environment. What is Natural Selection?
- 5. The process of natural selection relies on a few Important Factors Variation within a species is necessary Individuals must vary in appearance or behavior The variable traits must be inherited by offspring Factors
- 6. Competition Since food and resources are limited The offspring have to compete to survive Darwin called it Struggle For Existence
- 7. ⚫ Galapagos Finches ⚫ Beak size and shape adapted for specific type of food ⚫ Their beaks evolved due to natural selection. ⚫ Individuals with the right shaped beak to reach the food would survive.
- 8. There are the following types of natural selection which affect the phenotypes of individuals are: Directional Selection Disruptive Selection Stabilizing Selection Types of Natural Selection
- 9. ⚫ A type of Natural Selection in which the phenotype of the species tends toward one extreme. ⚫ Occurs when natural selection favors one extreme of continuous variation. ⚫ The favored extreme will become more common .
- 10. ⚫ The frequency of the melanic form of the moth increased ⚫ Their darker coloration provided camouflage against the sooty tree ⚫ Had a higher survival rate in habitats affected by air pollution
- 11. ⚫ A type of natural selection that removes individuals from the center of a phenotypic distribution and causes the distribution to become bimodal. ⚫ Occurs when natural selection favors both extremes of continuous variation. ⚫ The two extreme variations will become more common.
- 12. ⚫ Light-colored oysters are more coloration ⚫ allow organism to match its background ⚫ Dark-colored oysters blend into the shadows cast by the rocks ⚫ Intermediate-colored oysters would be most heavily preyed upon by the crabs
- 13. ⚫ Removes individuals from both ends of a phenotypic distribution, maintaining the same distribution mean. ⚫ Occurs when natural selection favors the intermediate states of continuous variation. ⚫ The intermediate states become more common.
- 14. ⚫ Very light-colored or very dark-colored oysters might be more frequently preyed upon by shore birds ⚫ Because they are more obvious on the oyster bar ⚫ The intermediate colored oysters become more common
- 15. The different genders in a species exert forces on each other that changes their appearance or traits. ✔ Natural selection favors traits that maximize ✔ The ability of an individual to compete ✔ Attract mates ✔ The ability to produce offspring ⚫ Sexual Selection
- 16. ⚫ The peacocks with the showier feathers are able to attract mates ⚫ Peacocks can fold up their tails, in danger of predator ⚫ Peahens are much duller and more camouflaged ⚫ They are the ones who guard the eggs and chicks ⚫ Survival of the next generation is very important
- 17. A type of selection that involves altruistic behavior Occurs when natural selection favors a trait that benefits related members of a group ✔ The protection of offspring ✔ Parent acts to preserve the gene pool of offspring ✔ At the expense of itself.
- 18. ⚫ Bees exhibit altruistic behavior by spending their lives serving the hive ⚫ The worker bee does not reproduce ⚫ Queen is able to produce many more related offspring
- 19. ⚫ Andersson, M. and L. W. Simmons. 2006. Sexual selection and mate choice. Trends Ecol. Evol., 21: 154-165. ⚫ Brunnander, B. 2007. What is natural selection. Biol. Philos., 22: 231-246. ⚫ Gavrilets, S. 2004. Fitness Landscapes and the Origin of Species. Princeton Univ. Press, 41:978-691. ⚫ Haldane, J. B. S. 1992. The Cost of Natural Selection. Curr. Sci., 14: 612-625. ⚫ Mayr, E. 1997. The objects of selection. Proc. Natl. Acad. Sci., 94: 2091-2094. ⚫ Pust, J. 2001. Natural selection explanation and origin essentialism. Can. J. Philos., 31: 201-220. ⚫ Williams, G. C. 1966. Adaptation and Natural Selection. Princeton Univ. Press, 8: 86-93. ⚫ Lenski, R. E. 2017. What is adaptation by natural selection. PLoS One, 13: 100-105.