Table 1. ANCOVA results of no-choice fertilization crosses.

species	source	df	type III SS	ms	F	P
A. palmata eggs
	Log sperm (linear)	1	1.33	1.33	18.83	<0.0001
	Log sperm* log sperm (polynomial)	1	0.04	0.04	0.51	0.479
	Cross	1	3.84	3.84	54.56	<0.0001
	Cross*log sperm	1	0.42	0.42	0.59	0.440
	Cross*log sperm*log sperm	1	0.06	0.06	0.81	0.37
	Error	64	4.51	0.07
	Total	66	9.37
A. cervicornis eggs
	Log sperm (linear)	1	0.29	0.29	5.06	0.031
	Log sperm* log sperm (polynomial)	1	0.27	0.27	4.67	0.037
	Cross	1	0.08	0.08	1.41	0.243
	Cross*log sperm	1	0.21	0.21	3.47	0.071
	Cross*log sperm*log sperm	1	0.2	0.2	3.7	0.062
	Error	36	2.08	0.06
	Total	39	2.76

ANCOVA was used to test differences in fertilization success as a function of cross type and sperm concentration. The dependent variable is the proportion of eggs fertilized (arcsine-transformed). The model consists of treatment group (conspecific vs. heterospecific cross) as the main effect, with sperm per milliliter (logistic transformation) as the covariate.