filazzola nstp presentation 2014
TRANSCRIPT
Variation in cushion traits is determined by feedback effects from beneficiaries
Filazzola, A. & Lortie, C.J.
Hypothesis
The abundance of beneficiary species negatively co-vary with cushion-plant traits, particularly reproduction, because of a parasitic consumption of microsite resources.
Statistics
Site Characteristics Cushion Traits Beneficiary Traits
S1
S2
S3
Sn
C1 C12 C13 C1j
C21
C31
Ci1 Cij
B1 B12 B13 B1j
B21
B31
Bi1 Bij
Step 1• PCA of landscape vs. Cushion• Step-wise regression to reduce cushion traits
Step 2• PCA of cushion vs. beneficiary abundance
Step 3• GLM/GLMMs of key variables
Statistics
Step: AIC666.79Benf ~ Surface.area + Pen + Fruit.Den + Fruit.ht
Trait Df F Value Pr(F)
+ Decad 1 1.77 0.18460- Pen 1 2.67 0.10434+ Site 1 0.79 0.37517+ SWC.per 1 0.58 0.44686+ Dx 1 0.39 0.53334+ Concav 1 0.07 0.77806+ Branches 1 0.05 0.81705+ SWC.cen 1 0.00 0.96021- Surface.area 1 5.16 0.02456 *- Fruit.ht 1 5.19 0.02423 *- Fruit.Den 1 5.43 0.02120 *
Results summarized
Cushion fitness is not generally effected by site characteristics
The surface area of the cushion is correlated with both cushion fitness and beneficiary cover
Beneficiary cover is the strongest determinant of cushion fitness
Why Fitness?
• Seed set/fitness is associated with competitive strength and availability of soil resources (Cornelissen et al. 2003)
• Competition in nutrient-poor systems strongly determines plant fitness (Aerts 1999)
• Reducing a plants fitness is a form of competition
• Easily measurable response
Implications
Previous studies have examined functional variability of plants because of cushions
Cushion
Open
Almeida et al. 2012. Plant Ecology & Diversity
ImplicationsOther studies have examined functional variability
of strictly cushions
He et al. 2013. Plant Species Biology
Implications
Findings are similar to that of Schöb et al. 2013
Community Ecology TheoryPlant trait researchDominantsi.e. cushions
Plant trait researchSubordinates
i.e. beneficiaries
Conclusions
Further support for the cost-of-facilitation theory (in terms of fitness)
Highlight necessity of treating a plant community as a response surface
Links
Presentationhttp://www.slideshare.net/AFilazzola/filazzola-nstp-presentation-2014
R-Scripthttp://dx.doi.org/10.6084/m9.figshare.1225923