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BGYB51H3 Lecture 21 Notes Nov 19

Biological Sciences
Course Code
Maydianne Andrade

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BGYB51H3 Lecture 21 Notes
-females are the agents of selection in intrasexual selection
-females increase their fitness through direct or indirect benefits
-sperm transfer ends after 20 minutes of copulation even if female is still eating prey, males
take prey from female after 20 minutes
-genetic quality involves males having heritable traits that can give higher fitness for offspring
-experimental manipulation eliminates confounding variables that might mask possible sexual
-females prefer males with the most elaborated ornaments
-cross-fostering offspring involves assuming equal environmental effects between offspring in
order to determine their heritability
-offspring with more elaborated ornaments have better genetic quality than other less
ornamented offspring
-males have much traits that are not connected to good genes that provide survival or
predator/parasite resistance
-sexy sons hypothesis is that certain traits give higher mating success for sons of females; not
indicators of genetic quality
-no survival benefits with traits that are not connected to good genes
-benefit of choosing male with trait only occurs if a large number of other females also prefer
this trait
-preferences in females may already exist as innate in their sensory system (sensory bias
-certain arbitrary stimuli can cause female responsiveness because of innate sensory system
-competition and choice act together in many populations to cause both direct and indirect
benefits together
-sex role reversal involves male parental care or large nutrient gift increasing parental
-sex role reversal involves male having a higher parental investment than females; females
compete while males are choosy
-variation in number of mating in females and less variation in males in sex role reversal
-basic differences in parental investment affect sex roles rather than sex roles depending on
maleness or femaleness
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