Mating Systems and Investment
Mating systems are behavioral patterns shaped by resource distribution and parental investment: the time and energy a parent commits to rearing offspring.
| System | Pattern | Primary Context |
|---|---|---|
| Monogamy | 1 male, 1 female | Biparental care needed |
| Polygyny | 1 male, many females | Resource monopolization |
| Polyandry | 1 female, many males | Reversed parental roles |
| Promiscuity | Multiple partners | No stable pair bonds |
Parental investment theory (Trivers) predicts that the higher-investing sex is more selective (choosy), while the lower-investing sex competes for access.
Sexual Selection Mechanics
Asymmetry in parental investment drives sexual selection, operating via two distinct mechanisms:
- Intra-sexual selection: Direct competition within one sex (usually male-male) for access to mates.
- Inter-sexual selection: Mate choice exercised by the opposite sex (usually female choice of displays).
Common pitfall: Assuming the choosy sex is always female. Investment predicts choosiness, not biological sex. In species like seahorses, males invest the primary parenting burden and are the choosier sex.