Sexual Selection Flashcards
How does sexual selection act?
Intrasexual selection
Intersexual selection
What does sexual dimorphism cause?
Different phenotypes in males and females
What are the different types of mating systems?
Monogamy - one male and one female
Polygamy - male and female have multiple partners
Polyandry - female has multiple partners
Polygyny - male has multiple partners
What does monogamy cause?
Little sexual selection
No sexual dimorphism
How was extra-pair paternity discovered?
Genetic fingerprinting
What is the mating system of Dunnocks?
Appear monogomous
Frequently polyandrous
What are the extra-pair paternity percentages in some birds?
Chaffinch - 17%
Blue Tit - 10-15%
Dunnock - 0-36%
Tree Swallow - 38-76%
Superb Fairy Wren - 75-85%
What does multiple partners lead to?
Intense sexual selection
Sexual dimorphism
What is intrasexual selection?
Competition between members of the same sex
What are some examples of intrasexual competitions?
Fighting
Mate guarding
What is sperm competition an example of?
Intrasexual selection
What is a Lek competition?
A gathering of males that compete with each other
Display with each other
Females observe the Lek
Females choose the best males
Lekking is very costly for males
What is intersexual selection?
Females (sometimes male) choose their mate
What do females gain from choosing a mate?
Access to resources e.g. courtship feeding (mainly in monogomous species)
Access to good genes (utilitarian - females choose genes that confer high survival of offspring
Access to good genes (attractiveness) - females choose attractiveness genes that make male offspring more attractive to females
What was the Anderson experiment?
Experimentally altered tail length of male Widowbirds
reduced tail = low mating success
increased tail = more mating success
