Mating systems Flashcards
Mating system classification, what this encompasses?
- Copulation behaviour
- Social organisation
- Parental care system
- Competition for mates
What is monogamy?
- 1 male and 1 female
- Can be long or short term bonds
- Often both sexes care for young
- Most birds, few mammals and fish
What is polygyny?
- Males associate with many females
- Females associate with single male
- Few birds and most mammals
What is Polyandry
- One female associates with many males
- Few birds, fish and mammals
- Fairly rare
What is Promiscuity (polygynandry)?
- Both sexes have several mates
- Either or neither sex care for the young
- Few birds, few mammals, many fish, reptiles and amphibians
What are the fundamental differences between male and females ?
- Gamete size
- Males have a higher reproductive potential than females
Evolution of mating systems (What is the general model?)
Ecology effects female dispersion which then in turn effects male dispersion.
What does female monopolisation by males and the mating systems depend on?
Clutton-brock
- Female group size
- Female range size
When solitary females are dispersed what male competition occurs?
Scramble Competition
What is scramble competition?
- When females cover a wide range (due to food searching)
- The range the female covers is not defensable by male
- Male search for fertile females and guard them until pregnant
- Leave to find other fertile females once pregnant
When females are social and occupy small ranges that are defendable by males what mating systems occur?
- Uni-male polygyny (small groups) e.g. colobus monkeys
- Multi-male polygyny (large groups) e.g. lions
What mating systems occur when large groups of females occupy large ranges?
- Lekking
- Lek polygyny
- Often results in extreme sexual competition and sexual dimorphism
What animal was used to show how ecology effects female dispersal
Grey-sided vole
Grey-sided vole: Does food distribution determine female dispersion?
Experiment 1
- Yes but males also converged food
- Was the male range size shrinking because of females or because the food source was shrinking?
Grey-sided vole: Does females range size effect male dispersion?
Experiment 2
- Captive females, radio-tracked males
- When females were clumped together, the males range size shrunk
- When females were spread over the larger area the males range size increased.
- Female dispersion determines male dispersion within an environment
