1. By: Jessica Browne and Alanna MacDonald
Lizards!!!!
By: Jessica Browne and Alanna MacDonald

2. Godfreya, Sihc, and Bulla
The response of a sleepy lizard social network to altered ecological conditions
Godfreya, Sihc, and Bulla

3. Introduction
Social Network: direct and indirect associations between all members of a population
Stability of these associations can vary - short term or long term partnerships (i.e. monogamy)
Gain a better understanding of how social networks respond to environmental changes

4. Introduction
Previous studies have typically involved comparisons of populations over ecological gradients
There have been conflicting results
Stanley & Dunbar (2013): in species of goat, social networks were stable among populations that varied in ecological conditions

5. Introduction
Chaverri (2010): bat clustering behaviour differed across populations with different conditions
Edenbrow et al. (2011): guppies showed differences in social behaviour in populations with higher predation risks
Trend disappeared when predation was experimentally manipulated

6. Introduction
Require long term study that tracks changes over time as there are ecological fluctuations
More specifically, do social interactions within a population remain stable over changing ecological conditions?

7. Introduction
Flexible populations are able to quickly adapt to ecological changes
But populations that retain their social structure are protected from rapid changes that may not be beneficial in the long term

8. Introduction
This study will examine the overall network stability, and the stability of different associations within a social network over 3 years that varied in ecological conditions
Will examine the Sleepy Lizard

9. Introduction Sleepy Lizard large, long lived Australian lizard
Occupies stable home ranges
In the spring, they form a monogamous pair for 20 weeks before they mate
Often re-establish those partnerships in subsequent years

10. Introduction Predictions:
Rainfall influences abundance of flower that lizards feed on
Reduced food makes the lizards less active
Therefore, expected that intersexual pairing would be reduced in drier conditions

11. Introduction But may be forced to aggregate around food resources
So predict that non-pairing interactions would increase in response to drier conditions and pairing interactions would decrease

12. Methods
Conducted in a shrubland in Southern Australia from
Sample Size:
2008 N=47 (27 ♂, 20 ♀)
2009 N=58 (31 ♂, 27 ♀)
2010 N=60 (30 ♂, 30 ♀)
Conducted from August to December
Annual rainfall and temperatures were recorded
© Google Earth

13. Methods
A GPS logger and a step counter were placed on each lizard and used to measure activity and location
The GPS recorded the location of the lizard every 10 minutes for 4 months of the year
Lizards were found every 12 days to replace batteries

14. Methods The weight and snout-to-vent length was measured
A regression was found to measure Lizard body condition
© Laboratorie Informatique & Systema

15. Home Range and Activity Pattern
Home Range was calculated by looking at the 95% minimum convex polygons, while accounting for overlap with other lizards
A lizard was considered active if it took more than 10 steps in 2 minutes
Two sample randomization test was used and mean difference in home range overlap was found

16. Social Networks
GPS locations were monitored and any time the lizards were within 2 meters, this was considered social contact
Since the GPS had a precision to 6 meters, anytime the lizards were within 14 meters was considered social contact

17. Network metrics used Many parameters were measured
Mainly, encounter rate and the number of social connections of each lizard were analyzed

18. Social Network Structure Analysis
Analyses were compared between years to investigate stability (lack of change)
Mantel test was used
Compared network metrics between years
Examined intrasexual and intersexual relationships
Picked 40 lizards to construct the networks

19. Results
rainfall
temperature

20. Results: Body Condition
•Body Condition was significantly lower in (ANOVA p<0.001)

21. Results: Activity
• Spent significantly more time active each year (ANOVA p<0.001)
number of steps

22. Results: Home Range Home range area remained stable (p=0.1)
More home range overlap in 2008
Follows predictions

23. Results: Associations
Observed number of associations of each individual was compared to a model of random associations
Observed number of associations was significantly lower than the random model
Came into contact with fewer than half of the individuals they would be expected to by chance
Avoidance of conspecifics

24. Results: Association Stability
•Plotted associations of one year against associations from another year to test for correlations to determine how similar each year was
•Male-female associations were correlated across all years – reflects the stability of pairing

25. Results: Association Stability
•Male-Male interactions were correlated between 2009 and 2010 (the wetter years)
•Different in 2008
•Female-Female interactions correlated between adjacent years

26. Results: Associations Strength
Primary pair interactions:
strongest interaction type in wet years
lower in the dry year than the wet years
Extra-pair interactions:
significantly stronger in the dry year than wet years
Intrasexual interactions:
no different across years

27. Discussion
Climatic changes made a significant difference in interactions, although the basic structure was maintained
In drier years, lizards conserved energy by reducing foraging time
Home range overlap increased during this time - likely so that lizards could remain in an area with plants

28. Discussion Lizards usually stayed within the same network positions
Fewer strong linkages in the dry year (2008)
There was less frequent intersexual contact
Male-male interactions were common each year

29. Conclusions
They had intended to look at climate change but not enough years were studied
Dry years may be limiting food supplies and therefore animal behaviour
Further study is needed

30. Questions?