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Theory of Sexual Selection

Theory of Sexual Selection. Darwin’s The Descent of Man, and Selection in Relation to Sex. Sexual Selection Darwin’s attempt to explain traits that defied natural selection. Intersexual Selection. “female-choice”

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Theory of Sexual Selection

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  1. Theory of Sexual Selection Darwin’s The Descent of Man, and Selection in Relation to Sex

  2. Sexual Selection • Darwin’s attempt to explain traits that defied natural selection

  3. Intersexual Selection • “female-choice” • Bateman’s Principle: the sex which invests the most in producing offspring becomes a limiting resource over which the other sex will compete

  4. Intersexual Selection

  5. IntrasexualSelection • “Male-male competition” • Strategies used to compete with members of the same sex for access to members of the opposite sex • Female ornamentation produced at expense of their offspring which makes them lose fitness

  6. Intrasexual Selection

  7. Sexual Dimorphism • Differences between individuals of different sex of the same species • Male is larger in most mammals • In insects, spiders, birds, reptiles, amphibians the female is usually larger

  8. Sexual Dimorphism

  9. Sexual Selection and Physical Attractiveness

  10. Coloration in Animals Female Mandrill: facial coloration proportional with age (signals reproductive ability) Three Spined Stickleback: Females prefer males with intense red coloration (signals parasite resistance, because parasites reduce intensity)

  11. Physical Attractiveness- Skin Coloration

  12. Physical Attractiveness- Skin • Skin color distribution influences perception of female face • Attractive signals correspond to high Estrogen/Testosterone ratios • Skin problems may signal a disturbance in E/T ratio and reduced reproductive ability

  13. Physical Attractiveness- Symmetry

  14. Physical Attractiveness- Symmetry • Phenotypic indicator of biological fitness • Fluctuating Assymetries (FAs) result from genetic and environmental stresses during development • Indicates developmental homeostasis • Cue of high parasite resistance (parasite theory) • Defense against parasites: genetic diversity (dependent on individual heterozygosity) • Heterozygosity related to symmetry of bilateral traits

  15. Physical Attractiveness- Scent • Androstenone- secondary sex characteristic (men give off three times more than women) • Secondary sex characteristics correlated with offspring survival • During ovulation, female is most fertile • Increase in sensitivity to androstenone

  16. Relativity in Physical Attractiveness • Female choice is modified by female’s viability • Female three-spined sticklebacks in worse condition show preference for less brightly colored males • In humans, relative height • Humans adjust preferences to increase pool of partners • Women who considered themselves physically attractive showed greater preference for symmetry in male faces

  17. Summary • Intrasexual and Intersexual Selection • Sexual Dimorphism • Physical Attractiveness • Coloration • Symmetry • Femininity • Scent • Relativity

  18. References • Bernhard, Fink, Grammer Karl, and Matts J. Paul. "Visible Skin Color Distribution Plays a Role in a Perception of Age, Attractiveness, and Health in Female Faces." Evolution and Human Behavior 27 (2006): 433-42. ScienceDirect. <http://www.sciencedirect.com/science?_ob=articleurl&_udi=b6t6h-4m04jfk 3&_user=961305&_coverdate=11%2f30%2f2006&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=c000049425&_version=1&_urlversion=0&_userid=961305&md5=b68ca079c97966e24723a5f170d31301>. • Derocher, Andrew, Andersen, Magnus, Wiig, Oystein. “Sexual Dimorphism of Polar • Bears.” Journal of Mammalogy 86 (2005): 895-901. Academic Search Premier. http://web.ebscohost.com.proxy-um.researchport.umd.edu/ehost/detail?vid=4&hid=14&sid=839ea357-13a0-410f-ba8e-6d1684f5723a%40sessionmgr8&bdata=JmxvZ2lucGFnZT1Mb2dpbi5hc3Amc2l0ZT1laG9zdC1saXZl#db=aph&AN=18746448 • Fisher, Maryanne L. "Female Intrasexual Competition Decreases Female Facial Attractiveness." Biological Sciences 271 (2005): 283-85. Jstor. <http://www.jstor.org.proxy-um.researchport.umd.edu/stable/4142828?&search=yes&term=intrasexual&term=selection&list=hide&searchuri=%2faction%2fdobasicsearch%3fquery%3dintrasexual%2bselection%26x%3d0%26y%3d0%26wc%3don&item=1&ttl=1602&returnarticleservice=sh>. • Grammer, Karl and Thornhill Randy. "Human (Homo sapiens) Facial Attractiveness and Sexual Selection: The Role of Symmetry and Averageness." Journal of Comparative Psychology 108 (1994). PsycARTICLES. <http://web.ebscohost.com.proxy-um.researchport.umd.edu/ehost/detail?vid=2&hid=112&sid=67ef4cbc-abc4-42d8- • Kodric-Brown, Astrid and Brown, James. “Why the Fittest are the Prettiest.” Sciences 25 (1985): 26. EbscoHost http://web.ebscohost.com.proxy-um.researchport.umd.edu/ehost/detail?vid=4&hid=6&sid=9cb7bd4e-5623-4c0f-ad788708c871ef80%40sessionmgr9&bdata=JmxvZ2lucGFnZT1Mb2dpbi5hc3Amc2l0ZT1laG9zdC1saXZl#db=aph&AN=4862140 • Lovich, J.E., Ernst, C.H., Zappalorti, R.T. & Herman, D.W. “Geographic variation in growth and sexual size dimorphism.” American Midland Naturalist 139 (1998): 69. Academic Search Premier. http://web.ebscohost.com.proxy-um.researchport.umd.edu/ehost/detail?vid=1&hid=16&sid=81322349-fced-4cc8-a061186fe9e89bdf%40sessionmgr3&bdata=JmxvZ2lucGFnZT1Mb2dpbi5hc3Amc2l0ZT1laG9zdC1saXZl#db=aph&AN=232450

  19. References 2 • Mesko, N. and Bereczkei, T. “Hairstyle as an adaptive means of displaying phenotypic quality.” Human Nature. 15 (2004): 251-270 http://researchport.umd.edu:80/V/5X73VS8XAY748XI92J51C4H25HLM7JSDXK17EK36D1I6TPSR8S-05012?func=quick-3&short-format=002&set_number=034318&set_entry=000001&format=999 • Neave, Nick, and Kerry Shields. "The Effects of Facial Hair Manipulation on Female • Perceptions of Attractiveness, Masculinity, and Dominance in Male Faces." Personality and Individual Differences 45 (2008): 373-77. ScienceDirect. <http://www.sciencedirect.com.proxy-um.researchport.umd.edu/science?_ob=articleurl&_udi=b6v9f-4sv0smc-1&_user=961305&_coverdate=10%2f31%2f2008&_alid=818562343&_rdoc=1&_fmt=high&_orig=search&_cdi=5897&_docanchor=&view=c&_ct=188&_acct=c000049425&_version=1&_>. • Ord, Terry J., Daniel T. Blumstein, and Christopher S. Evans. "Intrasexual Selection Predicts the Evolution of Signal Complexity in Lizards." Biological Sciences 268 (2001): 737-44. Jstor. <http://www.jstor.org.proxy-um.researchport.umd.edu/stable/3067621?&search=yes&term=intrasexual&term=selection&list=hide&searchuri=%2faction%2fdobasicsearch%3fquery%3dintrasexual%2bselection%26gw%3djtx%26prq%3dthe%2bevolution%2bof%2bsexual%2bdimorphism%2bb>. • Pawlowski, Boguslaw. "Variable Preferences for Sexual Dimorphism in Height as a Strategy for Increasing the Pool of Potential Partners in Humans." Biological Sciences 270 (2003): 709-12. Jstor. <http://www.jstor.org.proxy-um.researchport.umd.edu/stable/3558774?&search=yes&term=dimorphism&term=sexual&list=hide&searchuri=%2faction%2fdobasicsearch%3fquery%3dsexual%2bdimorphism%26wc%3don%26dc%3dall%2bdisciplines&item=5&ttl=15437&returnarticleservice=>. • Penton-Voak, I.S., Little A.C., Jones B.C., Burt D.M., Tiddeman B.P., and Perrett D.I. "Female Condition Influences Preferences for Sexual Dimorphism in Faces of Male Humans." Journal of Comparative Psychology 117 (2003): 264-71. PsycARTICLES. <http://web.ebscohost.com.proxy-um.researchport.umd.edu/ehost/detail?vid=1&hid=12&sid=b95cff88-5909-486f-ac6d-6d485d68762c%40srcsm1&bdata=jmxvz2lucgfnzt1mb2dpbi5hc3amc2l0zt1lag9zdc1saxzl#db=pdh&an=com-117-3-264>.

  20. References 3 • Rodrigo, Cardenas A., and Harris J. Lauren. "Symmetrical Decorations Enhance the Attractiveness of Faces and Abstract Designs." Evolution and Human Behavior 27 (2006): 1-18. ScienceDirect. http://www.sciencedirect.com.proxy-um.researchport.umd.edu/science?_ob=ArticleURL&_udi=B6T6H-4GPW3SV-9&_user=961305&_coverDate=01%2F31%2F2006&_alid=818572202&_rdoc=2&_fmt=high&_orig=search&_cdi=5031&_sort=d&_docanchor=&view=c&_ct=3&_acct=C000049425&_version=1&_urlVersion=0&_userid=961305&md5=40a0b8369e0734034fca6d52a22e7ddf • Schulte-Hostedde, A.I. “Female Mate Choice is Influenced by Male Sport Participation.”Evolutionary Psychology. 6 (2008): 113-124. Jstor. http://74.125.47.132/custom?q=cache:HPS5K8i32j0J:www.epjournal.net/filestore/EP06113124.pdf+Female+mate+choice+is+influenced+by+male+sport+participation+filetype:pdf&hl=en&ct=clnk&cd=1&gl=us&client=google-coop-np • Simmons, L.W. & Emlen, D.J. “No fecundity cost of female secondary sexual trait expression in the horned beetle Ontophagus Sagittarius.” Journal of Evolutionary Biology 21 (2008): 1227-1235. Jstor. http://www3.interscience.wiley.com.proxy-um.researchport.umd.edu/cgi-bin/fulltext/120736325/HTMLSTART • Thornhill, Randy and Gangestad, Steven W. “The Scent of Symmetry: A Human Sex Pheromone that Signals Fitness?” Evolution and Human Behavior 20 (1999): 175-201 http://www.sciencedirect.com.proxy-um.researchport.umd.edu/science?_ob=ArticleURL&_udi=B6T6H-3WWVBHG-5&_user=961305&_coverDate=05%2F31%2F1999&_alid=830877376&_rdoc=1&_fmt=high&_orig=search&_cdi=5031&_sort=d&_docanchor=&view=c&_ct=2&_acct=C000049425&_version=1&_urlVersion=0&_userid=961305&md5=b3b9730b021870055bf628a4298525aa • Thornhill, Randy, and Grammer Karl. "The Body and Face of Woman One Ornament that • Signals Quality?" Evolution and Human Behavior 20 (1999): 105-20. ScienceDirect.http://www.sciencedirect.com.proxy-um.researchport.umd.edu/science?_ob=ArticleURL&_udi=B6T6H-3W9CYB5-3&_user=961305&_coverDate=03%2F31%2F1999&_alid=818393669&_rdoc=2&_fmt=high&_orig=search&_cdi=5031&_sort=d&_docanchor=&view=c&_ct=2&_acct=C000049425&_version=1&_urlVersion=0&_userid=961305&md5=8975239e65f3179d6a7ee33333290b64

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