Sexual Selection Flashcards
What is sexual selection?
Natural selection for traits that increase reproductive success
What is anisogamy?
Sexual reproduction which involves the fusion of unequal gametes e.g. eggs and sperm
Why are eggs and sperm “unequal gametes”?
Eggs are large and expensive: produce a relatively small number of eggs
Females generally invest more in growing and caring for each offspring
Sperm are small and cheap: produce many numbers of tiny sperm
What is intrasexual selection?
Members of same sex competing to gain opportunities to mate with others
How do males in nature compete for access to females?
Fighting
Ritualised contests
Guarding females
Sperm competition
What is mate guarding?
Prevents other males getting access to fertile females
What is sperm competition?
Competition for inseminations between the sperm of rival males
What is intersexual selection?
Where one biological sex chooses mates to mate with
Selection favours females who choose the best possible males to mate with
What are the benefits of choosing good quality mates?
Good resources and parenting ability
Good genes
What is sexual conflict?
Conflicts of interest between females and males
e.g. male lions slaughter the cubs when they take over a new pride
Also, female mantids sometimes eat the males during mating
When do females compete for males in terms of sexual selection?
When males invest more in parental care than females
e.g. some birds like moorhens
Females lay eggs then start new nest
Males incubate the clutch
Describe the mating system, monogamy.
Having only one mate at a time
Describe the mating system, polygamy.
Pattern of having more than one mating partner at a time
Describe the mating system, polyandry.
Pattern of mating where the female has more than one male mate
Describe the mating system, polygynandry.
Both males and females have multiple mating partners in a breeding season
