Flashcards
Sexual selection
Cards in this deck (10)
- 1Sexual selectionnatural selection for traits that increase reproductive success
variation is inherited
variation between individuals - 2Anisogamyunqual gametes - female egg bigger than small sperm (females investiing more into reproductive act)
• 5ml of human semen could theoretically fertilise eggs of 2x USA population – females are a scarce resource - 3natural selectionvariation between individuals
this variation affects survival
variation is inherited - 4Male - Male competition = intra-sexual selectionRed deer - Roaring voice, antlers – secondary sexual characteristics - gives access to females – females watching (winner takes over harem)
1. roaring contest
2. parallel walking and boxing
3. antler-grappling
Mate guarding - damselflies and elephant seals - prevents other males getting acess
forced mating - rape in mallard ducks, hemipteran bug (injects sperm directly into the femal through her body wall) - 5sperm competitioncompetition for inseminations between the sperm of rival males e.g. remove rival sperm using barbed penis, plug the females genital opening (using type of cement they produce)
Male inject sperm into other males – into their testes (so they contain mixture of own sperm and rival sperm) - 6Female choice = inter-sexual selectionchoose the best possible males to mate with
- good resources and parenting ability
-good genes for offspring - 7How to impress females- defeat opposition
-defend a high quality territory
- provide nuptial gifts = courtship feeding
-advertise the genetic benefits of a good choice
1. have trait thats attractive to pass onto your sons = runaway sexual selection
2. • Strategic handicap – handicap to survival ability but strategic as it improves reproductive success (Peacocks tail) - 8sexual conflictconflicts of interest between males and females e.g. infanticide, sexual cannibalism
sexual conflict over parental care
e.g. kentish plovers (bird) both sexes incubate egg, either sex can desert in order to find new mate, deserted mate left to rais family - 9females compete for malesoccurs when males invest more in parental care than females
e.g. moorhens, phalaropes, jacanas
Females lay eggs and start a new nest – males incubate the clutch – ardent females & choosy males - 10mating systemsMonogamy - one mate at a time (European robin)
polygamy/polygyny - more than one mate (marsh harrier)
polyandry - female animal has more than one male mate (phalarope)
Polygyandry - two or more males have an exclusive sexual relationship with two or more females. (Kentish plover)
promiscuity - when males and females in a population mate randomly and with multiple partners. (aquatic warbler)
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- Degree Genetics Flashcards on Sexual selection, created by Sara Forghani on 19/05/2017.
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- Sara Forghani
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