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Sexual selection.pptx
- 4. Presented by Darwin in 1871 On his 2nd major book Descent of man and selection in relation to sex natural selection is special case of sexual selection Many extravagant trait that seem to reduce survival are important in mate choice
- 6. Natural selection support fittest organism but sexual selection produce trait that compromise survival Sexual selection arise through variance in mating success It favors gene selected by female that move in next generation
- 7. It depends not on struggle for existence but on struggle between males for possession of females Sexual selection occur when male compete for female and female choose male Can occur through two mechanism Intra sexual selection Inter sexual selection
- 8. Mating success determined by within sex interaction Male compete for access to mate Include intense fighting Male –male combat
- 10. Mating success determined by between sex interaction Male fight to attract female Involve Selective mate choice Female choose mate with preferred characters
- 12. Investment on number of gametes Worked on flies Difference in number of gametes produced by sexes Female become limited resource for which male compete Female tries to maximize her reproductive potential by finding best male
- 13. Male fertilize all egg she produces As sperm is cheaper than egg Sex which invest most in offspring will become limiting resource over which other sex compete Mating opportunity limits male reproductive success and fecundity limits female reproductive success
- 15. Role of investment in offspring Differential investment by sexes in gametes Sex that provide more parental care becomes limiting factor Sex that invest less compete for mate E.g. katydid
- 16. Female investment Male investment Size of egg large Number of egg limited Month of gestation Month of nursing Receive nuptial gift by male Small Almost unlimited No gestation No nursing Give nuptial gift to female