Coexistence patterns in a desert rodent community The relative importance of stabilizing mechanisms...
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Coexistence patterns in a desert rodent community The relative importance of stabilizing mechanisms of coexistence Glenda Yenni Department of Biology, Ecology Center Department of Math and Statistics Utah State University 2009 Annual Meeting of the American Society of Mammalogists, University of Alaska Fairbanks
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Transcript of Coexistence patterns in a desert rodent community The relative importance of stabilizing mechanisms...
Coexistence patterns in a desert rodent community
The relative importance of stabilizing mechanisms of coexistenceGlenda YenniDepartment of Biology, Ecology CenterDepartment of Math and StatisticsUtah State University
2009 Annual Meeting of the American Society of Mammalogists, University of Alaska Fairbanks
Negative frequency dependence in growth rates
Enable species to increase when rare
Indication of stabilizing mechanisms of coexistence (Chesson 2000, ‘niches’)
Empirical evidence in pair-wise interactions
A Niche for Neutrality, Adler et al 2007
Multi-species dominance and stabilization
0.0 0.2 0.4 0.6 0.8 1.0
-3-2
-10
12
3
Frequency
log
r
Fo Fo Fo
Fo = 0.2
S = -2
Fo = 0.6
S = -2
Fo = 0.15
S = -2
Fo = 0.15
S = -4
Portal LTREB
Chihuahuan desert Since 1977 20 ha, 24 plots
10 controls – equal access 8 k-rat (Dipodomys) exclosures 6 total rodent exclosures
Abundance, community E use
Portal LTREB
p=0.001, p=0.0004, p=0.004, p=0.007 p=0.000, p=0.03
Sevilleta LTER
p=0.0001, p=0.02, p=0.02 p=0.03, p=0.003 p=0.01
Coexistence
A Niche for Neutrality, Adler et al 2007
Coexistence predictions
0.0 0.2 0.4 0.6 0.8 1.0
-3-2
-10
12
3
Frequency
log
r
0.0 0.2 0.4 0.6 0.8 1.0
-3-2
-10
12
3
Frequency
log
r
+
++
++
++
++
+
++
++
++
+
+ +
++
++
+ +
++
+++
+
+
0.0 0.2 0.4 0.6 0.8 1.0
-3-2
-10
12
3
Frequency
log
r
+/- relationship btw strength of stabilization and mean population abundance 0.0 0.2 0.4 0.6 0.8 1.0
-3-2
-10
12
3
Frequencylo
g r
Stable coexistence
Competitive exclusion
+
+
+
----
--
Strength of stabilization
Fitn
ess
equi
vale
nce
Deterministic coexistence
+ positive relationship btw strength of stabilization and mean population abundance
- negative relationship btw strength of stabilization and mean population abundance
+/- coexistence
+/- competitive exclusion/stochastic extinction
Stochastic coexistence
+ positive relationship btw strength of stabilization and mean population abundance
- negative relationship btw strength of stabilization and mean population abundance
+/- coexistence
+/- competitive exclusion/stochastic extinction
Implications/ Future Directions
Rare species benefit from stronger negative frequency-dependence more than dominant species Strong stabilizing mechanisms aid persistence of non-
dominants in variable communities
Implications for the ability of changing regions (via invasive species, climate change) to maintain species richness
Explore entire coexistence space Apply to other coexistence models
Acknowledgments
Morgan Ernest for advising and support Peter Adler, Xiao Xiao Kate Thibault, Sarah Mohlman, and other past and future
fellow Portal RAs Selected Professions Fellowship, AAUW The Portal project is currently supported by NSF grant DEB-
0702875
Questions?
