Hamadryas Baboons. Hamadryas vs Savanna Baboons Hamadryas… Arabia, N-E Africa: dry country, less...
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Transcript of Hamadryas Baboons. Hamadryas vs Savanna Baboons Hamadryas… Arabia, N-E Africa: dry country, less...
Hamadryas Baboons
Hamadryas vs Savanna Baboons
Hamadryas…
Arabia, N-E Africa: dry country, less fruit, less grass?
Separate ~340,000 years
Hamadryas 20-25% smaller
Dimorphism: H MM striking from 3-4 years
Long mane; white whiskers; pink face, perineum
Fertile hybrids --- same species! Papio hamadryas
e.g. Hamadryas: Papio hamadryas hamadryas
Anubis: Papio hamadryas anubis
Troops = Sleeping groups
Hamadryas Social Organization
Troop: Up to > 600
Sleeping community only
Band: Largest social unit (~ 30-100)
May travel together or disperse
May fight other bands
No M-M fighting within bands
Clan: “Sub-band” (~10-20)
May forage independently
MM may look alike (e.g. Reds)
Little M/F dispersal
Rosso and Rossini of the Red Clan - they look alike.
Fights between bands
Inter-band supplanting
Fights between bands
Near band approaches. Fight starts on right.
Fights between bands
Inter-male contest for FF
M(R) chases M(L)’s F. M(L) intervenes.
1
2
Fights between bands
FF in M(L)’s attack shadow. M(L) does not “engage in battle”.
Body weight : FF 14.7 kg; MM 28.4 kg (twice FF’s body weight !)
Family (“one-male unit”) within clans
Prime M, FF (2-3, range 1-9); M = leader
70% bonds last > 3 years
M dominates FF within unit
Most grooming is by F to M
M can summon F with a look
M defends his infant
Certainty of paternity?
High-ranking mothers are more permissive parents.
Low-ranking mothers keep tight control on their infant’s whereabouts, sometimes by holding her infant by the tail.
N. Rowe, 1996
M intervenes if any other M tries to interact with his females
FF compete for M (e.g. by being child-like)
Female-female aggression within OMU: coalitions only with male!
Like among gorillas
Female-female aggression within OMU: coalitions only with male!
“Double signal” by female. Present to M; threaten opponent F.
“Protected threat” (seen only in captivity).
F(A) moves so as to be between M and F(B) (and presents to M).
So F(B) can’t threaten F(A) without threatening M also.
Paternity
Strong M-M respect:
No matings seen by other males within clan
Contracepted MM : FF stop breeding
FF solicit their own MM only
Anti-infanticide strategy by FF?
Coordination
How to meet at water-hole after leaving sleeping-cliff?
1. Mental map? Probable.Places visited more often are reached by more detours.
2. Communication of intention? Probable.
Clans separate 250 m from cliffReassemble at noon to drink/restJoint direction pre-fission (250 m) = waterhole directionNotifying at high rates Male “notifies” to ally (before turning R)
Ho: MM “make appointments” within bands
Life-history of hamadryas OMU
1. Initial unit.
Young AM (9-11 yr) + Juv F (2-3 yr)
No mating (F too young)
M herds, carries, sleeps-embracing F
M hugs juv F, initial unit
1. Initial unit
Formation
“Follower-M” forms bond with Juv F
M herds; lie flat and watch; walk ahead / look back
invite groom.
N.B. This establishes ‘respect’ by other MM before FF mates
Nervous mother
Grooming between MM of initial units
N.B. No grooming among breeding males!
1. Initial unit
‘Maternal’ Male in initial unit
1. Initial unit
2. Take-over Fight
Prime M loses FF to
(A) Non-breeding M within clan (e.g. Follower M)
or (B) Neighboring band
but No fight/take-over within the clan (M-M “respect”)
Question: Higher risk of take-over if more FF in the OMU?
Male stages within clan
Past prime BACHELOR; FORMER LEADER
Prime OMU LEADER
Late adolescent INITIAL UNIT LEADER; FOLLOWER
Early adolescent BACHELOR; FOLLOWER
STATUS
How do MM in OMUs avoid losing FF?Kummer’s field experiments
1. What creates the Hamadryas M-F bond?
Ho: Male herding behavior.
Transplant Anubis F into Hamadryas band
1 H-M “herds” (rocks cage, neck bite, expects follow etc)
A-F follows within 1 hour!!
Conclusion: H-M herding -> M-F bond
BUT: A-F keeps straying!!!
After a week, H-M gives up!!
Conclusion: H-M herding + H-F following -> M-F bond
Transplant H OMU to different H Troop! (at dawn)
--> M loses FF within 1 hour
Conclusion: M-M respect within bands protects the M-F bond.
2A. What protects the Hamadryas M-F bond within Bands?
Ho: Breeding MM within Bands respect each
other’s relationships with FF.
2B. What protects the Hamadryas M-F bond within Bands? Mechanism?
Test M-M dominance within a Band (HM1, HM2)
e.g. peanut test --> (HM1 > HM2)
Introduce new F to Low-rank M (HM2)
Allow high-rank HM1 to watch for 15 minutes (cf. Control, watch 0 min)
Introduce dominant HM1 to (F + subordinate HM2)
--> HM1 is inhibited
cf. Control, HM1 attacks!
Conclusion: M-M respect within bands results from knowing M-F bond.
Ho: MM respect within Bands comes from observing M-F relationship.
F has been placed on top of HM1’s cage.
HM1 moves as far as possible, and turns away.
HM2 grabs for F without inhibition.
2B. What protects the Hamadryas M-F bond within Bands?
Ho: MM respect within Bands comes from observing M-F relationship.
Control experiment: MM do not
observe each other with F.
Result: High-rank M wins.
Conclusion: M-M respect within bands results from knowing M-F bond.
2C. Does F choice influence M respect?
Ho: MM show less respect to the M-F bond if FF don’t like their own M.
Test: Rank F preference for M: approach, groom, etc
Allow Rival MM to attack/respect
Result: MM attack more if F preference for her
own M is low.
Conclusion:
M-M respect within bands results from
1- M1 knowing M2-F bond, AND
2- from assessing F’s preference for her own male.
Species differences in Sexual Behaviors
Anubis Hamadryas
♂
♀♀
♀♂
♂
♂♀
♀♀
♂
AnubisHamadryas
♂ ♀♀ ♀
♂ ♀♀ ♀
♂ ♀♀ ♀
♂ ♀♀ ♀
♂ ♀♀ ♀
♂ ♀♀ ♀
BandClanOMU
Hamadryas (compared to anubis):
• less fighting
• no dispersal
• more sexual consorting
Species differences in Sexual Behaviors
Anubis Hamadryas
Species differences in
SerotoninAnubis Hamadryas
• Serotonin is neurotransmitter and hormone.
• It acts as a sexual inhibitor.
• When serotonin is reduced in the body (with a neurotoxin), sexual
activities are increased in male rats.
Dixon (1998). Primate Sexuality
• Increasing the serotonin activity in the brain (with drugs) result in
reductions of sexual behavior in male rats, or…
• … inhibits erection in the male rhesus monkey
Hamadryas baboon
Savanna (anubis) baboon
SEROTONIN & BEHAVIOR: VARIATION BETWEEN SPECIES
Hybrids: inhibited males
Kaplan et al (1999)
Anubis Hamadryas(hybrid)
Serotonin index
Species differences in
SerotoninAnubis Hamadryas
See you next time !
Hybrid troops
Morphology and Behavior correlated in the hybrids?
Score MM by 7 physical features (e.g. mane length)
7 behavioral features (e.g. herding)
Result: Hybrids: behavior and looks are correlated.
Complex mixture of relationships… some bonding, some not
Origin: Hamadryas “Mate-raiding”? Expected, but not seen
Immigration by Hamadryas and Anubis MM -- yes
Hamadryas and evolutionary history.
Hamadryas and anubis differ consistently (wild + captive)
Female coalitions (H-, A+)
Female willingness to be herded (H+, A-)
Male herding (H+, A-)
Male respect (H+, A-)
What explains the Hamadryas system?
Kummer/Dunbar: male protects vs. predators
Henzi/Barret: male protects vs. infanticide
A. Low food density --> small groups
Wrangham: FF coalition in Indian langurs against Infanticide
FF coalition in olive and yellow baboons Infanticide rare
But chacma: FF allies occur but rarely, similar to Hamadryas!