1. Ring-tailed lemurMuriqui 1. Sexual monomorphism vs. dimorphism 2. Competition and social relationships “Phylogeny of behavior”

2. primates Female body size M/F body weight SEXUAL DIMORPHISM IN BODY WEIGHT tends to INCREASE WITH BODY MASS (RENSCH’S RULE)

3. 1.0 1.4 1.8 2.2 MonogamyMulti-male group One-male group M/F body weight More Females per Male Sexual Dimorphism in Body-Weight increases with # FF per M in group

4. 0.5 1.5 2.5 M/F Canine height MonogamyMulti-male group One-male group More Females per Male Sexual Dimorphism in Canine Height increases with # FF per M in group

5. i.e. importance of male fighting ability depends on OPERATIONAL SEX RATIO (OSR) More intense fighting expected if: 1.More males present at mating time 2.Fewer females 3.Longer interbirth intervals (IBI), e.g. Pongo 4.Shorter period of female sexual receptivity OSR = # males * IBI # females * # mating days/birth

6. Mitani et al.(1996) “Polygynous primates”- But data are from Anthropoids! R = 0.49, P < 0.01 2 Higher OSR Higher Sex. Dim.

7. Scramble competition All individuals equally affected e.g. Social group feeding in a tree Resources not economically defensible e.g. Mature leaves Fighting doesn’t help Competition  Resources are in short supply Contest competition Winners do better than losers Resources are defensible : e.g. fruits in a tree Fighting or dominance helps : Higher feeding rates COMPETITION AND RELATIONSHIPS

8. Competitive regimes WGS = Within-group scramble WGC = Within-group contest BGS = Between-group scramble BGC = Between-group contest

9. Competitive regimes and expected relationships: females Rep Success high if Aggression Agonistic kin support Dominance Rank stability Hierarchy Strong WGS Group Size low Rare Inconsistent Low Egalitarian, individualistic Strong WGC Rank high Common Unidirectional High Despotic, nepotistic van Schaik (1989) E.g.Baboon, ringtail Muriqui, bonobo

10. Sakis, Uakaris, Titis Part of the cebid group - Pitheciines (New World monkeys) Many speciesCallicebus titi monkey (10 species) Cacajao uakari(2 species) Chiropotesbearded saki (2 species) Pitheciasaki monkey (6 species) For photographs and brief account per species, see Primate Info Network http://pin.primate.wisc.edu/av/images

11. Callicebus cupreus discolor Monomorphic in body size and color Small, cohesive monogamous group Males are paternalistic Territorial

12. Callicebus moloch ornatus Callicebus donacophilus Callicebus personatus nigrifrons Callicebus personatus

13. Cacajao calvus BEARDED SAKIS AND UAKARIS Opposite of titi monkeys Large, more loosely structured groups Groups fission smaller feeding parties Large home ranges Large day ranges Males : no paternal care Little sexual dimorphism body mass/color

14. Chiropotes satanas Chiropotes albinasus

15. Pithecia monachus SAKIS Intermediate between titis/bearded sakis/uakaris Sexual dichromatism, bushy tail Small group size, small body mass Territorial Mothers are care-givers Males more as infants grow up Aggressive intergroup encounters

16. Pithecia pithecia

17. Muriqui Small sexual dimorphism Females 9.5 kg Males 12 kg Small canines in both sexes Ripe fruit preferred - but > 50% feeding time on leaf - up to 80-90% in dry season Large testes (high WCS) CONSERVATION ISSUE: ca 400 in wild, < 10 (?) in captivity

18. Muriqui social behavior Groups 15-60; stable OR “Molecular fission-fusion” INTERGROUP Male philopatry; female dispersal @ 5-6 years Non-territorial, but… … Aggressive intergroup at key foods  FF+MM active players … Mostly vocalizations rather than physical fights.

19. INTRAGROUP Very little aggression Egalitarian year-round Resource displacement = rare Kin support = rare Rank stability low No contest competition for sex (!) FF brief estrus, solicit MM No mate-guarding Embracing Muriqui social behavior

20. Predictions for Male-male Scramble competition MM closer when resting > feeding M mating success @ M-F association Sharing occurs when F at ovulation Strier et al. (2002) Behaviour

21. Predictions for Male-male Bonding system MM bonds occur MM value specific MM MM ‘allies’ share FF Maternal brother don’t associate but… … Brothers share FF during mating Strier et al. (2002) Behaviour

22. Predictions MM closer when resting > feeding MM bonds occur MM value specific MM (high-maters) MM ‘allies’ share F mating M mating success @ M-F association MM that share FF tend to be kin Puzzles. Why are some MM attractive to other MM? Age-related? Why do MM tolerate “high-approachers”? ? Strier et al. (2002) Behaviour

23. Sexual Behavior Estrous FF mate promiscuously Several MM may line up to mate After intromission, the M is motionless for 2-7 minutes (!) 10-28 of thrusting The M’s ejaculate hardens to form a vaginal plug but… … removed by the female or other males and dropped. Adults deposit urine on their hands (?) Rowe (1996) Pictorial guide to the primates

24. Measuring relationship value “Hinde index” for a dyad: “% approaches - % leaves”

25. 50% 0 -50% Hinde index for body contacts = (% body contacts initiated by Infant) - (% body contacts terminated by Infant) Rhesus monkeys Answer : The mother ! } } I joins, M leave M joins, I leave Q: Who’s responsible for mother-infant contact declining as infant grows? Infant age (weeks) 12 weeks

26. Will you protect me ?

27. Wrangham and Pilbeam 2001. In All Apes Great and Small Reconstructing the past