Table 2.

Results from phylogenetic generalized least-squares regression models explaining sperm behavior-based hook morphology.

Response	Predictor	t	P	R2	λ
Proportion of cells in aggregate	Hook length	−0.355	0.741	−0.21	1.000 (0.15, 1)
	Hook width	−8.351	0.014	0.97	1.000 (1, 0.01)
	Head width	12.613	0.006
	Total sperm cells	−2.193	0.160
	Hook area	−2.300	0.105	0.51	1.000 (1, 0.11)
	Head area	2.680	0.075
Number of cells in aggregate	Hook length	−0.575	0.596	−0.15	1.000 (0.18, 1)
	Hook width	−53.746	<0.001	1.00	1.000 (1, 0.01)
	Head width	76.135	<0.001
	Total sperm cells	−12.787	<0.01
	Hook area	−1.852	0.161	0.31	1.000 (1, 0.10)
	Head area	2.047	0.133
Sperm curvilinear velocity	Hook length	−1.670	0.170	0.26	1.000 (0.19, 1)
	Hook area	−2.809	0.107	0.56	1.000 (1, 0.09)
	Head area	2.996	0.096
	Total sperm cells	1.606	0.249
	Hook width	−4.607	0.019	0.84	1.000 (1, 0.01)
	Head width	5.312	0.013

In all models, the branch length transformations for lambda, λ, were set using maximum likelihood (‘ML’), with lower and upper boundaries for the lambda estimation indicated within parentheses. Stepwise model simplification comparing models with and without total sperm cells (density) did not change any of these results (based on AIC values). Reported R² values are adjusted values. Significant results at the p < 0.05 level are bolded, shaded areas signify different models.