Evolution_and_Sex

Evolution_and_Sex - Evolution and Sex Reading: Text Section...

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Evolution and Sex Reading: Text Section 8.3
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Objectives Why is sex beneficial?
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Many Eukaryotic Organisms Can Reproduce Asexually Volvox Colonies Hydra
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Asexual vs. Sexual Reproduction Parthenogenesis : Aphids Fig 8.16 parthenogenesis = virgin birth
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Parthenogenesis Obligate Parthenogenesis: Entire species consist of females only, which reproduce by making identical clones of themselves Cyclical Parthenogenesis: Populations consist of females that reproduce clonally throughout most of the year, but at certain times males are produced, and sexual reproduction occurs. Parthenogen, Parthenogenetic, Parthenogenic
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Why Sex? Maynard Smith proposed a null model to address this question, assumptions: Females reproductive mode does not affect the number of offspring that she can make Females reproductive mode does not affect the probability that her offspring will survive What happens in a population where there is asexual reproduction and sexual reproduction
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Parthenogenic females produce only females Sexual females produce a mixture of males & females in equal ratios Figure 8.17, pg. 304 There must be benefits to sex Two fold cost of sex
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Maynard Smith’s model in Practice Females reproductive mode does not affect the number of offspring that she can make In some species, males provide parental care
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This note was uploaded on 09/28/2011 for the course BIOL 301 taught by Professor Pickard during the Spring '09 term at Waterloo.

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Evolution_and_Sex - Evolution and Sex Reading: Text Section...

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