Chapter 11

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• Whena sexual populations cannot take away harmful mutations driving them extinct due to lack of crecombination Muller's ratchet
• Sexual offsrping will be more adapted to survival than asexual, which can speed evolutionary response to remain fit against parasites, threats etc. Red Queen effect
• same sized gametes Isogamy
• different sized gametes Anisogamy
• Disruptive selection leads to very unequal gamete sizes
• any selection arising from relative fitness differences associated with non-random success in competition for access to gametes for fertilization Sexual selection
• The four episdoes of sexual selection Female choice, male to male competition, cryptic female choice and sperm competition
• When a gene flow is reduced because of differences in the timing of when gametes are accessible for fertilization between different species Temporal isolation
• 2 closley related species of monkey flowers are each pollinated by a different species (bees and hummingbirds). Ecological isolation
• –most species have to engage in copulatory courtship in order to fertilise the eggs with the males sperm Copulatory behavioural isolation
• when the gametes of 2 species are incompatible and can’t produce a zygote. Gametic isolation

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