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Table 3 Linear (β) and quadratic (γ) selection differentials for phenology, biomass, and ecophysiology traits

From: Phenotypic plasticity of natural Populus trichocarpa populations in response to temporally environmental change in a common garden

Trait

Year

β

γ

Bud set

2009

0.255***

− 0.043***

2010

0.386***

−0.027

Canopy duration

2009

0.121***

−0.032

2010

0.240***

−0.042

Growth period

2009

0.187***

−0.036*

2010

0.347***

−0.102***

Leaf drop

2009

0.232***

−0.023

2010

0.342***

0.201***

Post-bud set period

2009

−0.162***

−0.047**

2010

−0.316***

−0.108***

Height: diameter

2009

0.082***

−0.060**

2010

0.008***

−0.073*

Active growth rate

2009

0.293***

−0.032**

2010

0.399***

−0.023

Amax

2009

−0.077***

−0.024

2010

0.002

−0.092

Amax/mass

2009

−0.053**

−0.042*

2010

−0.054

−0.038

C: N

2009

− 0.025

0.027

2010

0.045

−0.065

∆leaf

2009

−0.054**

−0.050

2010

−0.110***

−0.037

δ15N

2009

−0.002

−0.019

2010

−0.028

−0.038

gs

2009

−0.093***

−0.035

2010

−0.089**

−0.090*

LMAsummer

2009

−0.037*

−0.018

2010

0.027

−0.051

Narea

2009

0.006

0.010

2010

0.007

−0.046

Nmass

2009

0.031

0.010

2010

−0.059

−0.062

NUE

2009

−0.082***

−0.006

2010

−0.011

−0.047

WUE

2009

0.029*

−0.007

2010

0.097***

−0.093**

  1. Significance: * P < 0.05, ** P < 0.01, *** P < 0.001
  2. The signs and magnitudes indicate the direction and strength of the linear (β) or non-linear (γ) selection on each trait in either year. Significant F-tests indicates nonzero selection differentials (Additional file 1: Table S4) on a trait in a given year. The selection differential describes both direct and indirect selection on each trait. It equals to the regression coefficient of relative fitness onto standardized trait values after controlling the effect of any unmeasured traits on fitness by including a random intercept term, ‘Genetics’ (i.e., average Euclidean genetic distance using genetic marker data). For quadratic selection, a negative, significant value of γ indicates stabilizing selection, while a positive value is evidence for disruptive selection (tests detailed in Additional file 1: Table S5). Both selection analyses were visualized in Additional file 1: Figures S9 and S10