The realized niche of the endangered blunt-nosed leopard lizard (Gambelia sila) is determined by interactions between native shrubs and invasive annual grass. Alessandro Filazzola, Westphal M., Powers M., Liczner, A.R., Johnson, B. & Lortie, C.J.
Shrubs and invasive grass predict lizard occurrence in an arid shrubland
Aug 21, 2015
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The realized niche of the endangered blunt-nosed leopard lizard (Gambelia sila) is determined by interactions between native shrubs and invasive annual grass.
Alessandro Filazzola, Westphal M., Powers M., Liczner, A.R., Johnson, B. & Lortie, C.J.
Filazzola & Lortie 2014
Lortie et al. 2015
Bruno et al. 2003
Lortie et al. 2015
Direct
Thermoregulatio
n
Territory
landmark
Shelter
Intermediaryspecies
Indirect
Increase food availability
Protection from
predators
Burrows
Distributional records for blunt-nosed leopard lizardUSFWS 1998
Ciervo-PanocheNatural Area
Carrizo PlainNational Monument
Hypothesis: Plant-interactions either positive from shrubs or negative from invasive grasses can scale to other trophic levels such as lizards.
P1: Lizard presence relatively higher in shrubs than open microsites
especially shrubs with high canopy cover
P2: Burrows & trails are more frequent in shrubs and strongly predict lizard
occurrence.
P3: Lizards occurrence will be more frequent in areas of high shrub density
and low annual cover (RDM)
Methods
Methods
ShrubsDimensionsVolumeCanopy coverBurrowsTrailsScat
Annual cover Residual dry matter weight
Methods
Data analyses
Ordinary kriging -> for interpretation of intermediary points
Statistical tests -> Logistic regression
Auto-correlation -> Getis-Ord cluster analysis
Microscale results
= 1.87; max = 7
p < 0.001
Microscale results
N.S.LengthHeightVolumeTrailsBurrows
P < 0.001CanopyRDM
P1: Lizard presence relatively higher in shrubs than open microsites
especially shrubs with high canopy cover
P2: Burrows & trails are more frequent in shrubs and strongly predict lizard
occurrence.
P3: Lizards occurrence will be more frequent in areas of high shrub density
and low annual cover (RDM)
+
-
+?
Conservation & management
50% of shrubs from 2013 also had scat in 2014
Lizard families from the previous year
The “Perfect” shrub
Conservation & management
Lizards have short home ranges, 2-4 hectares (Warrick et al. 1998)
Implications for ecology
Shrubs may be integral in structuring animal communities
Implications for ecology
Shrubs may be integral in structuring animal communities
Shrubs extend the realized niche for animals
Implications for ecology
Shrubs may be integral in structuring animal communities
Shrubs extend the realized niche for animals
“Facilitation renaissance”
Thank you!!
The Ecoblender labBLM Hollister Field OfficeDeborah WoollettThe Working Dogs’ crewTia, Orby, Seamus
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