Table 2

Standardized linear (β) and quadratic (γ) selection gradients (± SE) derived from regressions between male mating success and body length (TTL) or between male mating success and FTG length (see Figure 2 for abbreviations) in a natural population and in two sets of simulated data.

Natural population

Directional selection gradient

Stabilizing/Disruptive selection gradient

β

p

γ

p

TTL

0.014 ± 0.042

0.739

0.114 ± 0.072

0.311

FTG

-0.003 ± 0.042

0.934

0.012 ± 0.070

0.937

Simulation 1

FTG

0.182 ± 0.040

< 0.001

-0.074 ± 0.066

0.269

Simulation 2

FTG

0.054 ± 0.042

0.198

-0.178 ± 0.070

0.012

In Simulation 1 female size distribution was shifted towards larger values. In Simulation 2 the variation of male size distribution was increased. P-values in the table were calculated by the least squares analysis. But p-values were also determined by logistic regression and the resulting statistically significant (p < 0.05) selection coefficients are given in bold.

Han et al. BMC Evolutionary Biology 2010 10:359   doi:10.1186/1471-2148-10-359