Relations between sperm competition and sperm dimensions across marsupials.

Phylogenetically controlled multiple regression analyses revealing the effect of relative testes mass on sperm dimensions. All variables were log10 transformed prior to analysis. The superscripts following the λ value indicate significance levels (n.s. p>0.05; *p<0.05) in likelihood ratio tests against models with λ = 0 (first position) and λ = 1 (second position). The effect size r calculated from the F values and its non-central 95% confidence limits (CLs) are presented. Confidence intervals excluding 0 indicate statistically significant relationships. The p-values and CL that indicate statistical significance are shown in bold. Abbreviations: n: number of species in each analysis.