Sexual conflict and Sexual selection PO Flashcards
sexual reproduction involves
gamete formation (egg and sperm)
Characteristics of a sperm?
small, unlimited and ‘cheap’ to produce
Characteristics of an egg?
large, relatively scarce and cost a lot to produce
sexual reproduction involving sperm and egg is called?
Anisogamous sexual reproduction
What is there an asymmetry of between males and females when looking at rearing offspring?
Parental investment and Parental effort
What is parental investment?
effort put into rearing an individual offspring
What is parental effort? (PE)
effort put into rearing all offspring produced during lifetime
What does the asymmetry between parenting roles lead to?
sexual conflict
What do differential PE lead to?
differential ideal strategies to maximise reproductive success.
Where male PE is lower… they should?
maximise reproductive success by ruthless promiscuity
What are harems?
wives of a polygamous male
Why should females be choosy and coy when choosing mate?
to offset high cost of reproduction
What roles do females and males have when choosing mate?
Females will do choosing, males will compete for access to female
What will females mainly invest in?
PE
What will males mainly invest in?
ME = Mating effort - acquiring mates
Define Monogamy
M and F form exclusive pair bond
Define Polygyny
M mates with several Fs
Define Polyandry
F mates with several Ms
Polygyny + Polyandry =
Polygamy
If PE is equal =
more equal ME
If PE is unequal =
less equal ME
What is sexual selection?
‘the decent of man and selection in relation to sex’
Females being choosy and males being competitive for access to females leads to….
selection of traits solely concerned with increasing mating success
Two types of sexual selection:
Intrasexual selection and Intersexual selection
What is intrasexual selection?
Where Ms compete for access to Fs, those best equipped to win will pass on their genes to next generation.
What can Intrasexual selection lead to?
Tusks, antlers, claws, large muscles and large teeth
Intrasexual selection leads to ________, M becomes a _______
- dimorphism
2. fighting machine
Example of effects of intrasexual selection?
Red deer stag, compete for Fs, strongest stags command largest harems, led to sexual dimorphism, M more bulky than F, M possesses antlers (employed in aggressive, interlocked fights)
Example of intrasexual selection, after copulation?
Black winged damsel fly, F may mate with several Ms prior to laying eggs, M developed ability to remove existing sperm from F sperm storage organ, Ms penis has lateral horns and spines, scrubs out competitor’s sperm prior to release of own sperm
What is intersexual selection?
reluctant females will show preference to males who show clear evidence of material resources and/or ‘better’ genes.
Example of material resources in intersexual selection?
Hanging flies, F hanging flies will mate with a M only if provides large insect to eat during copulation. Allowed duration of copulation is relative to insect size.
Example of genetic benefits in intersexual selection?
genetic benefits may underlie development of elaborate adornments
Case study on genetic benefits (Widow bird, Kenya)
M = sparrow sized with up to 50cm tail, F prefer M with longer tail, Andersson studied 36 M widow birds.
4 groups: shortened tail, elongated tail, control 1 (untouched) control 2(cut and repaired tail). Mating success measured as number of active nests in territory.
Long tailed Ms did better than controls or short tailed.
What is Fishers hypothesis of the ‘runaway process’? (Widow bird case)
starts with preference for Ms with increased flying ability, get positive feedback between Fs, and longer tails. yet not optimal for flying purposes.
What is Zahavi’s handicap hypothesis?
Elaborate adornments= handicap in day to day survival. Demonstrated Ms ability to survive in spite of handicap.
Only healthy animals will show fully developed secondary ______________ (include adornments)
sexual characteristics
Adornments are a sign of?
sign of health
intersexual selection not only leads to elaborate adornments , but also to ________ and ________
- courtship displays
2. rituals
