A talk I presented at Behavior 2011: Joint Meeting of the Animal Behavior Society and International Ethological Conference (Bloomington, IN), summarizing my dissertation. You can find more information on the research presented here at: https://impactstory.org/TinaWey and https://sites.google.com/site/tweyresearch/home

1. Quantifying social attributes and their
consequences in yellow-bellied marmots
Tina W. Wey1
& Daniel T. Blumstein2
1
University of California, Davis; twwey@ucdavis.edu
2
University of California, Los Angeles; marmots@ucla.edu
Tom Uhlman

2. Causes and consequences of
sociality
 Sociality is widespread and varied
 Questions
 Why is there social variation?
 What are the consequences of social variation?
 Multiple levels
 Proximate and ultimate causes of sociality
 Individual and group variation
 Many ways to quantify sociality

3. Interactions are important
INTERACTIONS
RELATIONSHIPS
SOCIAL STRUCTURE
Hinde 1976

4. Social network variation

5. Outline
 Social network structure and consequences in
yellow-bellied marmots
 How are marmot social networks structured at
multiple levels?
 Do individual social attributes have fitness
correlates?

6. Yellow-bellied marmots
Rocky Mountain Biological Laboratory
Marmota flaviventris

7. Fieldwork
 Data
 Trapping
Adriana Maldonado-Chaparo
Karisa Tang

8. Fieldwork
 Data
 Observations
 2003-2008
Brian Smith
Carol Glazer

9. Marmot social networks

10. Quantifying network variation
 Affiliative (cohesive, “friendly”) vs. agonistic (competitive,
“unfriendly”) interactions
 Multiple levels of analysis
 Networks
 Dyads
 Individuals
vs

11. Network structure – “Friendly” and
“unfriendly” networks differ
Measure Affiliative Agonistic

12. Network structure – “Friendly” and
“unfriendly” networks differ
Measure Affiliative Agonistic
Density
N = 24
Z = -3.741
P < 0.001

13. Network structure – “Friendly” and
“unfriendly” networks differ
Measure Affiliative Agonistic
Density
Reciprocity
N = 24
Z = -3.741
P < 0.001
N = 24
Z = -3.657
P < 0.001

14. Network structure – “Friendly” and
“unfriendly” networks differ
Measure Affiliative Agonistic
Density
Reciprocity
Clustering
coefficient
N = 24
Z = -3.741
P < 0.001
N = 24
Z = -3.657
P < 0.001
N = 24
Z = -0.343
P < 0.001

15. Dyadic structure
Wey & Blumstein 2010 Animal Behaviour
 Age and kinship influence affiliation preference
 Marmots are more friendly to others in the same age class and
closer relatives
 Less consistent “rules” for who fights
Friendship Fighting
Age class
Sex
Kinship

16. Individual variation
 Age and sex influence social tendencies
 Older and male marmots are crankier
 Older marmots receive fewer affiliations, and initiate more and
receive less aggression
 Females receive affiliation from more partners, and males initiate
aggression to more
Affiliative Agonistic
Initiation Reception Initiation Reception
Age
Sex
Wey & Blumstein 2010 Animal Behaviour

17. Social variation can have
associated consequences
 Individual social variation influences reproductive
success
 Social bonds can improve fitness, especially for females
 Aggression and dominance can result in differential fitness
 Increased parasitism is often a cost of sociality
 Increase with group size (Côté & Poulin 1995, Bordes et al. 2007)
 Social behavior is expected to influence parasites (Møller et al.
1993, Altizer et al. 2003)

18. Consequences of individual social
variation in marmots
 Background:
 Dominance rank is associated with reproductive success in
males but not females (Huang et al. 2011 Ethology)
 Larger males tend to be dominant
 Social cohesion predicts female dispersal (Blumstein et al. 2009 Proc B)
 Social variation is heritable (Lea et al. 2010 PNAS)
 Predictions:
 Social cohesion would improve female reproductive success
 Aggression would predict males reproductive success
 More social individuals would have more parasites

19. Consequences of individual social
variation in marmots
 Defined social attributes
 Measured fitness correlates
 Annual reproductive success
 Parasites – fleas and intestinal parasites
 Fit separate mixed models with social variables as
predictors
 Female and male reproductive success analyzed separately
 Included a spatial component
 Burrow overlap

20. Defining social attributes
 Many possibly measures of connectivity, which reflect different but
related aspects of social connectivity
Degree Number of social partners
Out-degree Number social partners initiating to
In-degree Number social partners receiving from
Strength Total interactions (weighted degree)
Out-strength Total interactions initiated
In-strength Total interactions received
Closeness Overall connectivity in the network
Betweenness Importance as a connection point in the network
Embeddedness Social integration

21. Defining social attributes
Network Social Variable Description
Affiliative PC1: Connectivity Overall affiliative
connectedness
PC2: Affiliation
strength
Weighted affiliation
Agonistic PC1: Victimization Received aggression,
embeddedness
PC2: Bullying Initiated aggression,
Betweenness
Spatial Overlap Crowding experienced

22. Social cohesion did not improve
female reproductive success
 Friendlier females had fewer offspring
 Crowded females had fewer offspring
Affiliation
strength
Annual
reproductive
success
Spatial
overlap
Annual
reproductive
success
N = 228
P < 0.001
N = 228
P = 0.014

23. Size and aggression were important
for male reproductive success
 Bigger males had more offspring
 More aggressive males had more offspring
Relative
mass
Annual
reproductive
success
Bullying
Annual
reproductive
success
N = 44
P < 0.001
N = 44
P = 0.044

24. Parasites were not a cost of
sociality
 Social factors did not influence ectoparasite or
endoparasite infection
 Ectoparasites: fleas (N = 185)
 Males had more fleas (P = 0.030)
 Endoparasites: gut protozoa (N = 428)
 No significant trends
Sociality Parasites

25. Summary
 Social attributes explained reproductive success, but not
parasites
 Friendlier females had lower reproductive success
 Contrasts with more highly social species
 Constraints and competition?
 Male bullies had higher reproductive success
 Consistent with results from dominance
 Parasites do not appear to be a cost of sociality in marmots
 Results differ from findings in other systems (Corner et al. 2003)
 Consistent with previous research on group measures in marmots
(Arnold & Lichtenstein 1993, Van Vuren 1996)

26. Conclusions
 Quantified and distinguished biologically
important attributes of sociality examine
structure and possible consequences
 Examining social network variation offered
complimentary insights to other approaches

27. Acknowledgements
Collaborators
Brian Huang
Ferenc Jordán
Amanda Lea
Julien Martin
Weiwei Shen
Karisa Tang
Adriana Maldonado
Help & Feedback
Rick Grannis
Peter Nonacs
Peter Narins
Blumstein lab
UCLA ATS stats consulting