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Riki Krentz & Allyson MacDougall

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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 DD
10 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?


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