Sexual Conflict Flashcards
What is sexual conflict?
A form of evolutionary conflict where males and females do not share interests over reproduction.
Sexual Conflict in Dunnocks
Males arrive and establish territories. Females arrive later. Sometimes, persistent secondary (beta) males are accepted as territorial partners. Males co-defend the territory, while being mutually hostile, when the female is fertile. She solicits copulation from both of them.
- Cloacal pecking: male stimulates her to eject sperm.
- Frequent copulation: higher in trios than in duos.
In the end, both share the paternity.
Females solicit copulation from worse males (betas) because their share of mating access is correlated with how much they feed young afterwards. Reproductive success is better with two males feeding.
Arms race between sexes. Their interests are not the same!
Sexually Antagonistic Genes
Genes that are beneficial in one sex but deleterious in another. Selection on one sex can interfere with the other sex’s adaptive evolution.
Sexually Antagonistic Genes and Zebra Finches
Males have red beaks and cheek patches, females have orange beaks.
Beak colour is highly heritable.
It also has the opposite effect on male and female reproductive success.
- Males with red beaks have the highest fitness.
- Females with orange beaks have the highest fitness.
Intralocus Sexual Conflict
Alleles/genes at one locus having opposite effects on reproductive success in males vs females.
(ie. hip width in humans, beak colour in zebra finches)
Interlocus Sexual Conflict
Alleles that promote female fitness harm male reproductive success, and alleles that promote male sexual selection harm female fecundity/reproductive success.
(ie. seminal fluid in drosophila)
Sexual Conflict in Drosophila
Seminal fluid proteins are toxic to females and shorten their lifespan. Females build resistance to this fluid. This is a chemical arms race.
Exp. Monogamous lines did worse as they did not have chemical resistance to male fluid.
Sexual Arms Race: Water Striders
Dangerous to mate, as they mate on water. Males on top, female begins to sink. This can attract fish who see the movement; they come up from the bottom, usually getting the female but allowing the male to escape.
Morphological changes to combat this.
- Males can clasp females.
- Females have anti-clasping spines to push them off.
Sexual Arms Race: Ducks
Males nearly drown females to mate with them. Unpaired females often are mated by multiple males. Both males and females have complex sexual organs for sperm competition and impeding copulation respectively.
