Mating Systems and Parenting

Females of the long-tailed dance fly, Rhamphomyia longicaudaadvertise to gift-bearing males. The female inflates her abdomenmaking herself appear as large as possible in the group of circling females

Sex role reversal in the jacana

Donald Jenni and Gerald Collier (1972)

Sex role reversal in the jacana

Femalesdominantdo not provide parental caremate with many malesdefend super-territories

Malessubmissiveprovide parental caremate with a single female

Result: Operational sex ratio female biased Females compete for access to males

Classification of Mating SystemsBased on the Number of Copulatory PartnersPer Individual and Nature of the Pair Bond

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--P

olyg

amy

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Evolution of Mating Patterns

Monogamy

Habitat: scattered, renewable resources

Result: neither sex can monopolize the members of the other sex

Polygyny

Habitat: patchy resources

Result: females choose males with best territories

or:

Females gregarious

Result: males monopolize female groups

Mating systems in mammals and birds

Human mating systems

The frequency of different mating systems in 849 different humanssampled cross-culturally

Evolution of parental care

• Certainty of paternity hypothesis

• Gamete order hypothesis

• Association hypothesis

• Biological attributes of a lineage

(e.g. mammals vs. birds)

Evolution of parental care

• Certainty of paternity hypothesis(sex most certain of genetic relatedness should care)

• Gamete order hypothesis(sex that lacks the opportunities to desert should care)

• Association hypothesis(sex that is most closely associated with the offspring should care)

• Biological attributes of a lineagemammals: embryos develop inside the mother’s body

birds: embryos develop outside of the mother’s body