Determinants of male reproductive success in wild long-tailed macaques—male monopolisation, female mate choice or post-copulatory mechanisms? Shay Omahen, Sam Sotuyo, Seth Matsumura Determinants of male reproductive success in wild long-tailed macaques—male monopolisation, female mate choice or post-copulatory mechanisms?. Behavioral Ecology and Sociobiology, 59, Engelhardt, A., Heistermann, M., Hodges, J.K., Nurnberg, P., & Niemitz, C. (2006). Determinants of male reproductive success in wild long-tailed macaques—male monopolisation, female mate choice or post-copulatory mechanisms?. Behavioral Ecology and Sociobiology, 59,

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Introduction Contest among males for access to mates should lead to social systems with alpha male.Contest among males for access to mates should lead to social systems with alpha male. Findings show that complete monopolization of females are difficult resulting in lower status males having paternity.Findings show that complete monopolization of females are difficult resulting in lower status males having paternity. What other mechanism operate in paternity determinism?What other mechanism operate in paternity determinism? –Synchrony in female ovarian cycles –Fighting ability –Coalition forming by subordinate males –Mate guarding Female choice also plays a role in paternity determinism.Female choice also plays a role in paternity determinism.

Method Consisted of a group of long-tailed Macaques from the Ketambe Research Station in Indonesia.Consisted of a group of long-tailed Macaques from the Ketambe Research Station in Indonesia. –8 adult females –5 adult males –Several sub-adults/juveniles –2 infants Fecal matter was collected from:Fecal matter was collected from: –females to determine ovulation cycle and pregnancy. –Infants to determine paternity. There were 2 different ovulation cycles:There were 2 different ovulation cycles: –KA (estrogen levels were elevated but ovulation did not occur) –SA (estrogen levels elevated and ovulation did occur)

Behavior Observation Two or three observers followed a group of Macaques for a mean time of 11.1 hours and recorded any sexual interaction between adult group members.Two or three observers followed a group of Macaques for a mean time of 11.1 hours and recorded any sexual interaction between adult group members. –Female approaches male and vice versa –Mounting behaviors –Refusal of sexual interaction –Forced copulation Dominance hierarchy was determined by display of “bared-teeth-face” (submissiveness).Dominance hierarchy was determined by display of “bared-teeth-face” (submissiveness).

Results 11 ovarian cycles were observed11 ovarian cycles were observed –6 conception cycles –4 ovulatory non-conception cycles –1 anovulatory cycle 6 out of 11 cycles females were consorted by alpha males 97% of the time (SA).6 out of 11 cycles females were consorted by alpha males 97% of the time (SA). Remaining 5 cycles (KA, non-monopolization), alpha males consorted females 26% of the timeRemaining 5 cycles (KA, non-monopolization), alpha males consorted females 26% of the time More mating partners observed during KA, but most copulations were observed by alpha males.More mating partners observed during KA, but most copulations were observed by alpha males. During SA, dominate males chased females away from other males 30% of the time (mate guarding).During SA, dominate males chased females away from other males 30% of the time (mate guarding). Sneak copulations by subordinate males were very low while being consorted by an alpha male.Sneak copulations by subordinate males were very low while being consorted by an alpha male. All 6 infants born during the period were fathered by high ranking males.All 6 infants born during the period were fathered by high ranking males. Females also mated more often with higher ranking malesFemales also mated more often with higher ranking males

Discussion Monopolization of females is timed according to the females SA cycleMonopolization of females is timed according to the females SA cycle –This ensures paternity –Monopolization not seen during KA; would be a waste of energy. Mate guarding was observed during this periodMate guarding was observed during this period –3 of the 6 infants conceived during the SA cycle had alpha males who guarded the females throughout the entire fertile phase. –Resulted in very minor proportion of copulations by subordinate males during SA cycle.

Discussion Subordinate males tend to be insistent while mating. Those rejected by females would simply try again and would be successful.Subordinate males tend to be insistent while mating. Those rejected by females would simply try again and would be successful. –Caused females to be sexual permissive by harassment and intimidation. –Forced copulations were observed but were very rare. Coalition formations by subordinate males were expected but none were observed.Coalition formations by subordinate males were expected but none were observed. –Could be due to fear of retaliation by an alpha male.

Critical Review Liked:Liked: –All the subordinate males had to do was be persistent in order to mate with a female –Dominant males father most of the offspring ultimately making their offspring carry on the good genes –In all of the cycles, consortships were male-maintained in 100% of the consort time. Disliked:Disliked: –The sample size was too small –The observation time was for a few months (11 ovulation cycles) Which only allowed for 6 pregnanciesWhich only allowed for 6 pregnancies –The descriptions of the 2 types of ovarian cycles were unclear

Test Questions 1)T/F: Fecal matter was collected from females to determine ovulation cycle and pregnancy. 2)T/F: During non-monopolization cycles, alpha males spent more time consorting with females then during monopolization periods. 3)T/F: Mate guarding was observed to be an effective method of male reproductive success 4)Dominance hierarchy was determined by display of: A: pacing B: bared-teeth-face C: hair to body ratio D: grooming 5)Which of the following behaviors was NOT observed: A: Female approaches male and vice versa B: Mounting behaviors C: Nuptial gifts D: Refusal of sexual interaction 6)SA cycle describes: A: estrogen levels elevated and ovulation did occur B: estrogen levels were elevated but ovulation did not occur C: estrogen levels were decreased inhibiting ovulation D: none of the above