BIOL321 Lecture Notes - Lecture 16: Slime Mold, Cuckold, Thomas Robert Malthus
29 Apr 2016
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Document Summary
Sex involves the production of offspring from the union of gametes. Making offspring without sex is called parthenogenesis (partheno=virgin) Parthenogenesis is not a good long term method. Long term benefits of sex: thought to have greater evolutionary responsiveness, and maintains greater diversity. Sexually reproducing female has as many grandchildren two fold cost of sex . If the disadvantages outweighed the advantages, then a mutant allele would make everyone asexual. Therefore, there are short term advantages of sex. Muller"s ratchet (asexual organisms can only accumulate mutations, they can"t go backwards) Beneficial in a frequently fluctuating environment: parasitism is thought to be a factor for sexual selection, red queen hypothesis. Female-only reproduction is not the same as cloning. Automixis is where the eggs become haploid and fuse again to allow for mixing: but heterozygotes decrease over generations. Daphnia: in good conditions will do all-female reproduction, in bad conditions they do sexual reproduction (cyclic parthenogenesis)
