Presentation at Ecological Society of America, August 2013. Minneapolis, USA. –Oral Paper Angeli, N. F., K. Lips, G. V. DiRenzo, and A. Cunha. “Effects of density on spacing patterns and habitat associations in the Neotropical Glassfrog Espadarana prosoblepon.”

1. Prime real estate matters:
effects of population density
on spatial distributions of a
Neotropical glassfrog
Nicole F. Angeli1,2, Grace V. DiRenzo2,
Alexander Cunha3, and Karen R. Lips2
1Applied Biodiversity Sciences, Texas A&M University
2Department of Biology, University of Maryland, College Park
3Organismal and Evolutionary Ecology Program, Harvard University

2. Random
Different patterns predict processes
Many Neotropical stream frogs are aggregated (Atelopus varius, Pounds and Crump,
1987; Craugastor punctariolus, Ryan, Lips and Eichholz, 2008)
Uniform Clustered
(Clark, 1946; Diggle, 1985; Ripley, 1991; Bivand et al., 2008)

3. Clustered animals may
fight for resources
‘Limiting wars’
Maynard Smith and Price, 1973
Espadarana
prosoblepon;
Jacobson, 1985
Espadarana prosoblepon are aggregated
(CD=3.215, Witters and Lips, unpub)
Why do E. prosoblepon
cluster, and why do we care?

4. Declines in amphibian community at Omar
Torrijos H.D. NP, El Copé, Coclé, Panama
t =-24.44, df=486, P < 0.0001 Lips et al. 2006 PNAS
Quantify lethal and non-lethal effects of declines

5. Males: night, on stream banks;
Fighting, calling, mating;
lifespan ~ 5 years
(Jacobson, 1985; Guayasamin et al., 2009)
Females: cryptic
(Savage, 2002)
Juveniles: hatch and fall into
stream leaf litter to develop
(Cisneros-Heredia et al., 2006)
Espadarana (Centrolene) prosoblepon
Espadarana prosoblepon

6. Can the spatial organization of E.
prosoblepon change over time and space?
1. Does clustering occur on the streams?
Map male E. prosoblepon along streams
2. Will clustering change before and after Bd?
Detect changes in dispersion at varying densities
3. Are clusters based on resources or interactions?
Quantify animal arrangement and habitat

7. 4-200 m permanent stream
transects
Loop
Cascada
Silenciosa
Guabal
Visual Encounter Surveys
extending 2 m onto stream banks
Adults sexed by calling and
presence of humeral spines
Individual Toe Clips
(Heyer et al., 1994)

8. Microhabitat variables
Canopy
Veg at 0.5 m
Veg at 1.0 m
Veg at 1.5 m
Sand
Gravel
Cobble
Boulder
CWD
Stream Width
Stream Depth

9. Complete Data Set:
X=13 years
225 surveys
480 meters of habitat data
N= 1,678 male E. prosoblepon
881 unique males
- X-Y locality data
- Individual marks

10. Density of captures during 225 surveys
annualized over 13 years
Loop Guabal Cascada Silenciosa
Percent change in
abundance after Bd -46.3% -5.9% -68.3% -31.8%
Years with frogs: 11 11 8 7

11. Low intensity,
no frogs
a. Visualize clusters using
density maps smoothed with
Gaussian kernel
(Baddeley and Turner, 2005)
b. Kuldorff (2006) SatScan
Statistic to identify clusters
independent of space, time
Distance from stream (meters)
1. Identify and compare hotspots over time
TransectLength(meters)

12. 2. Detect changes in dispersion at varying densities
a. Detect patterns using linearized Ripley’s K
b. Use derived inflection points to calculate nearest
neighbor and inter-cluster distance
(Bikhofer et al. ,2006; Cowling, 1998; O’Driscoll ,1998; Stoyan ,1992; Ripley, 1981)

13. 3. Predict frog locality by microhabitat traits
a. Transform
variables with PCA
b. Use mixed effects
generalized linear
models to assess
predictability

14. 1. Frog hotspots before and after Bd
Twenty-one hotspots,
9 persist over all years (42.8%)
Post-decline:
8 disappear and 4 appear
…..independent of local density.

15. 2000 2001 2002 2003 2004 2005 2007 2010 2011
Results: Loop
* * **
* * ** * * * *
* ** * * *
* *
Clusters p<0.01*
TransectLength(meters)

16. Results: Cascada
*
2000 2001 2002 2003 2004 2005 2006 2007 2010 2011 2012
*
*
*
* * *
**
*
* *
*
*
*
* *
**
*
*
* **
Clusters p<0.01*
TransectLength(meters)

17. Results: Guabal
2000 2001 2002 2003 2004 2005 2011 2012
* ** * **
* *
** * *
**
*
Clusters p<0.01*
TransectLength(meters)

18. Results: Silenciosa
2000 2001 2002 2003 2004 2006 2012
*
*
*
*
*
*
*
*
*
*
** *
***
*
Clusters p<0.01*
TransectLength(meters)

19. P=0.45
P=0.45
P=0.29
P=0.03
2. Results: Cluster arrangement differs among transects
but not PRE and POST

20. P=0.36
P=0.17
P=0.49
P=0.53
Results: Nearest Neighbors does not change
PRE and POST, or among transects
Nearest-neighbor
0.692±0.74 m

21. 3. Can we predict frog abundance by PC-transformed habitat?
Pre-decline Post-decline

22. Summary: No changes in dispersion occur before
and after Bd arrives in the system
Individuals interact similarly, and cluster arrangement
varies by transect
Pre Post Pre Post Pre Post Pre Post

23. Are clusters hotspots for resources?
E. prosoblepon clusters of new individuals persist in the same
locations with similar habitat-associations

24. New and unique contributions
E. prosoblepon clusters persist in the same locations,
individuals interact similarly,
…..independent of local density.

25. Community analyses
of disease transmission
Microhabitat attributes of disease
See changes tadpole community at
by DiRenzo, Graziella et al.,
at 4:00 in L100B (COS 71).
Future Work

26. Acknowledgments
Lips lab at University of Maryland, College Park
Appalachian Lab: Dr. Robert Gardner and Dr. Matt Fitzpatrick
National Science Foundation provided support to KRL
TAMU herpetology for support and comments
Tweet me for R code
and conservation news
@auratus_nicole

27. Can we predict frog abundance by PC-transformed habitat?
2001 GLMM Model Coefficient T-value P value
Intercept 1.534 5.788 >0.001
PC1 -0.413 -2.294 0.034
PC2 0.098 0.383 0.705
PC3 0.062 -0.363 0.720
2012 GLMM
Intercept 0.802 3.264 >0.001
PC1 0.129 0.930 0.365
PC2 0.201 1.334 0.199
PC3 0.278 1.586 0.131
PRE
POST

28. Cluster arrangement varies by transect, but
individuals interact similarly
Nearest-neighbor
0.692±0.74 m

29. Summary: Vegetation is always important
1. Vegetation is important
PRE and POST Bd on
streams
2. Changes in substrate
(small to large) and
canopy (open) in the
Post years
PRE POST
Microhabitat
Canopy
Veg at 0.5 m
Veg at 1.0 m
Veg at 1.5 m
Sand
Gravel
Cobble
Boulder
CWD
Stream Width
Stream Depth
Microhabitat variables
Canopy
Veg at 0.5 m
Veg at 1.0 m
Veg at 1.5 m
Sand
Gravel
Cobble
Boulder
CWD
Stream Width

30. El Copé,
Panama
Espadarana prosoblepon distribution
(BerkeleyMapper 2.0)
700 m elevation
8°40’ N, 80°37’17” W

31. Costa Rica
Colombia
Caribbean Sea
Pacific Ocean
m

33. Loop Cascada Guabal Silenciosa

34. Vegetation is always important