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Lecture 7

Lecture 7 8.docx

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Lecture 7 8 -The evolution of sexual selection specifically proves to be probably less efficient than asexual reproduction -In aphids, sexual reproduction begins when females morph into males later into the season -Possibly, this is due to a crowded, uncertain and difficult environment -Uncertainty is hence linked to sexual reproduction -In water hyacinths, flowering and sexual reproduction occurs around the edges, resulting from difficult environments/less water -Since asexual reproduction produces many more offsprings, sexual reproduction is a mutation from the ancestral asexual reproduction -The reproductive rate of sexual reproduction requiring two individuals, means slower reproduction but at the same time greater variance in offspring -Sexual reproduction meant fitness has become a lot higher, overcoming the numbers game -Sexual reproduction meant that overtime different genes, say ABC, spreads much slower in asexual reproduction, but in sexual environments ABC spreads rather quickly -Asexual reproduction is usually average on the fitness scale, while sexual reproduction has a wider distribution, and hence more possible individuals with greater fitness -There are some organisms with the propensity to survive hard times, and their genes will persist -The red queen hypothesis -Host and parasite evolutions, protein which will be created in order to combat parasites demonstrates this red queen hypothesis -One problem of sexual reproduction is the danger of inbreeding, which creates the problem of inbreeding depression -With this, allelic frequencies remain unchanged -Among cheetahs, this is believed to be the case of Cheetahs who experience a population bottleneck, as all the genes for cheetahs are homozygous, there are no heterozygous genes -Compared to random mating, completely inbred populations lose their heterozygous genes -Inbreeding depression has demonstrated a reduction in fitness, and overall the population fitness decreases with further inbreeding of individuals -Among birds, egg failure has greater occurrences with greater inbreeding -The mortality rate among children of first cousins compared to children of unrelated parentage, showed greater mortality rate among them -Among prairie c
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