Table 3.

Evolutionary analysis of sperm intracellular ATP concentration and sperm size using BayesContinuous (BayesTraits v. 2.0). Maximum likelihood estimate (MLE) of evolutionary tempo (δ), ancestral state (α) and directional trend (β).

	δ MLE			[R]andom walk  versus [D]irectional
characters	δ	BFa against δ = 1	interpretation	α	β	BFa [R] versus [D]	interpretation
sperm [ATP]	2.55	8.02**	temporally late change	0.026	1.05	2.82*	[D] increasing
midpiece length	1.54	1.22n.s.	gradual change	10.64	87.09	7.21**	[D] increasing
total sperm length	1.51	0.75n.s.	gradual change	11.57	92.76	3.30*	[D] increasing

^aInterpretation of Bayes factors [51]: BF < 2: no evidence against the null hypothesis (i.e. n.s.); BF = 2–6: positive evidence against the null hypothesis (*); BF 6–10: strong evidence against the null hypothesis (**).