1. Riki Krentz & Allyson MacDougall
Social and genetic factors mediating male participation in collective group defence in black howler monkeys
Riki Krentz & Allyson MacDougall

2. Hypotheses Asymmetrical benefits Kinship Social relationships
Sires howl more than non-sires
Kinship
Relatives should participate more frequently together than non-relatives
Social relationships
Spatial association groups howl more frequently than non-groups

3. Hypotheses Kinship Social relationships
Why do they have to be howling together?
Does this include female-male?
Social relationships
Do they even form social relationships?
Spatial proximity = sociality
Riki - if they don’t act agonistically or affiliative towards one another?

4. Methods No information on amount of females in group Female howling
N = males = 28 females
21 in copulation chart… 7 immature females?
38 adult and subadult females in genetic testing
Female howling
Male-female dyads?
Allyson
if you’re howling because of family… what about mothers and sisters? are there male-female dyads?

5. Methods Adult, subadult, juvenile male distinction not given
No data on juveniles at all
Do they howl?
2 members who became subadult “now included”
Riki

6. Methods 3 consecutive days Habituation to researchers Spaced more?
Look a monthly cycling of behaviors?
Habituation to researchers
“Spontaneous” howls may be due to presence of researcher
Allyson
hormonal and behavioural
howling at researcher could be for other reason than threat

7. Methods
Intragroup calls due to separation and alarm calls were not included
How did they know that this is why they were howling?
What is an alarm call?
Riki

8. Methods Overall group scan sampling - 15 min intervals
Identification of dyad distance - 2m
Was this an eyeball measure?
Participation included many behaviors other than just howling
Shaking trees
“Being vigilant”
Allyson

9. Methods Exclusion of extragroup individuals howling because N=15
Maybe this is important?
Should have been included
Riki

10. Methods
“The identical multilocus genotypes for two pairs of males (MF-RC and KB-SB) indicated that these pairs of males comprised the same individuals”
Same monkeys who left one group and joined another.
Interference with howling motivation because old social/kinship ties?
Allyson

11. Allyson

12. Results
“Could not assess paternity for 7 infants born during the study because these newborns disappeared before faecal samples could be collected”
Did they die?
Interference with paternity
Riki

13. Riki

14. Results Sires participated in howling bouts more than non-sires
BUT “it is unlikely that the monkeys can determine who sired offspring since almost everyone copulated”
Are they participating because they are parents?
Riki

15. Riki

16. Discussion
Neither kinship nor proximity (social relationships) predicted mutual howling
Hypotheses 2 & 3 rejected
Hypothesis 1 is viable
Allyson

17. Central Male
Should have asymmetrical benefits in group, mating governance, female proximity
Do noncentral males howl?
Mixed results
Found no central male for ⅘ groups, then later said none of the groups
Riki
mixed results from other studies showing whether or not non central males howl

18. Central Male Claimed that no groups had central males
Due to even distribution of mating opportunities
But each group had asymmetry in initiation and participation of howling
Member who could be “central male” also had sired offspring
Allyson

19. Central Male Group Male Initiation Participation Unites BQ >90 DD10 50
Pakal 1 PK KN 20 40
Allyson

20. Discussion Will howl more when threat is higher
Seeing vs. hearing another group
Can’t assume visualizing = higher threat
Did not look into resources such as proximity to feeding grounds or females
Maybe they saw other groups and didn’t howl?
Allyson
can’t assume only thing causing threat is being able to see another group
more intergroup encounter threats than response calls **
may have seen other groups and didnt howl at them
should look at when theres something to guard not just howling cuz they see another group

21. Discussion
Group defence may have evolved from mutualism and not kin selection
Because non-sires and subadults also sometimes howled
But do not explain any further
Offered many weird theories
Free-riders, indirect fitness benefits
Riki

22. Questions?