Mating Systems and Parenting

Females of the long-tailed dance fly, Rhamphomyia longicauda advertise to gift-bearing males. The female inflates her abdomen making 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  Females dominant do not provide parental care mate with many males defend super-territories  Males submissive provide parental care mate with a single female Result: Operational sex ratio female biased Females compete for access to males

Classification of Mating Systems Based on the Number of Copulatory Partners Per Individual and Nature of the Pair Bond ----Polygamy ----

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 humans sampled 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 lineage mammals: embryos develop inside the mother’s body birds: embryos develop outside of the mother’s body