Aphrodisiacs, Love Potions, and Other Recipes from Cupid s Kitchen. Emily Adamson & Savannah Strang

Transcription

1 Aphrodisiacs, Love Potions, and Other Recipes from Cupid s Kitchen Emily Adamson & Savannah Strang

2 Discussion Why do aphrodisiacs emerge as an adaptative advantage? Examples?

3 Aphrodisiacs Males do better if females only mate with him Aphrodisiacs are one way to manipulate females mating with other males Conflict of interest starts evolutionary battle Thwart a female s previous and future lovers while avoiding getting thwarted himself Example: Make a female smell so bad to prevent males from getting close Red deer roaring Females come into heat sooner and give birth earlier in the spring Early spring births increase calf survival

4 Aphrodisiacs- Seminal Fluid Contains many factors and proteins Australian field cricket factors stimulate egg laying Housefly 12 active proteins; some bind to receptors in female s brain reducing or eliminating her sex drive Fruitfly 80 proteins, most roles are unknown Disable other males sperm Sperm more difficult to remove Stimulate egg laying and increase female aggression towards males

5 Drosophila melanogaster Experiments with forced fruit fly monogamy Males evolve to be less manipulative than females Females are more vulnerable to male manipulation Experiments where females were not allowed to evolve Males became supermales Were better at inducing monogamy in females

6 New Species Rock-boring sea urchin vs. oblong sea urchins Bindin protein on sperm attaches to egg Different bindin types on sperm can lead to new species Rock-boring produce different types of bidin Reproductive proteins evolve extremely quickly! Promiscuity can lead to new species more quickly Maybe because of battle of the sexes

7 Lysin Protein that allows sperm to enter the egg in abalone mollusk by breaking through the egg envelope Lysin evolving in response to changes in the envelope but not the other way around VERL large molecule with repeated units mutations spread quickly through each unit abalone is engaged in an evolutionary pursuit

8 Homesexual Activity More common than people think! Bonobos Dolphins- copulate with turtles, sharks, and eels. Penis when erect has a hook on it Why do they do it? For pleasure: Stump-tailed macaque females achieve organism from both male and female copulation Can facilitate teamwork in male baboons Or antisocial: Razorbills mount other males to show aggression Desperation: Octopuses where partners are scarce

9 How could homosexuality persist? Three conditions for a trait to persist: 1. Needs to be a genetic basis so subject to natural selection 2. It must be exclusive- some individuals who only do homosexual behavior and don t reproduce 3. Must make up a significant part of the population Can t determine any of these factors- even in humans

10 Why it might still be around Don t have to reproduce to spread your genes Ants and bees that slave away for a colony Increase reproductive success of relatives Organized groups where only some individuals are capable of breeding like naked mole rats Favored for selection- heterozygote advantage Malaria example Theoretical: Homozygous of one gene is hetereosexuality Homozygous of alternative allele is homosexuality Heterozygous is highly fertile heterosexuality

11 Genes function differs between sexes One gene could cause increased fecundity in females and exclusive homosexuality in males Advantage to females so great that it persists Would help to spread the gene Fruit fly experiments Found that at larvae stage there aren t any genes that are beneficial to males or females In adults, different genes give different benefits Shows that theory is plausible

12 Discussion Will it ever be possible to explain the persistence of homosexuality? What would be needed to prove its existence and persistence?