Biology 1201A Lecture Notes - Lecture 18: Genetic Drift, Mendelian Inheritance, Mutational Meltdown
21 Nov 2016
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Document Summary
The evolution of sex: sex is the exchange of genetic material between individuals. In sexually reproducing organisms, gametes fuse to generate new combinations of alleles. Eg. in producing gametes, exchange of alleles due to crossing-over in meiosis i. Reproduction without sex: asexual reproduction predominant mode in single-celled organisms, genetically identical off-spring = clones, do exchange some genetic material. Sex in asexually reproducing organisms: having biological sex without reproduction. Parthenogenesis: reproduction by female from unfertilized eggs (no sex), the eggs are not fertilized, there is no exchange of genetic material. Costs of sex: competition for mates (sexual selection). Takes energy: exposure to predation by attracting mates. In trying to become more attractive to a mate, you are becoming more attractive to predators: td"s. Evolutionary cost of sex: why would anyone exchange genetic material at all, breaking up a successful combination of genes in exchange for potentially flawed combinations in your offspring. Two-fold cost of sex: cost of producing males.
