Biology 1001A Lecture Notes - Jash, Painted Turtle, Echiura
10 Jan 2013
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Document Summary
Sex originated as a way of overcoming dna damage by using recombinational dna repair mechanisms. Any genetic variation created is an accidental by-product. The production of genetic variation is the primary reason for he persistence of sex. More mutations accumulate with asexual than with sexual reproduction in the water flea. Sex is advantageous to organisms that exist in variable environments and that parasitic elements such as transposons and plasmids initiated or promoted sexual fusion as a mechanism to infect other cells. Sexual crossing in a population allows single individuals to incorporate different beneficial mutations from other members through mating and genetic recombination. Enable relatively rapid combinations of existing mutations. Additional genetic variation allowing a population to persist in a changing environment. Different modes of genetic sex determination: penis fencing in flatworms. Hermaphrodites-consisting of both male and female parts. Some have two penises giving a decided advantage: temperature-dependent mechanisms.
