Table 1.

Comparative analyses for effects of placental invasiveness and interdigitation on life history traits

					Difference between intercepts
	Test for fit				Epitheliochorial vs. hemochorial and endothelochorial			Trabecular and villous vs. labyrinthine
	n	LRT	df	P	Estimate ± SE	t	Pace of life	Estimate ± SE	t	Pace of life	λ	r2
Offspring per year	131	5.39	1	0.020	—	—	—	−0.11 ± 0.05	−2.34*	↓	0.94	0.37
Gestation period	155	14.96	1	<0.001	—	—	—	0.69 ± 0.17	4.01***	↓	0.81	0.56
Age at first reproduction	110	8.85	2	0.012	−0.86 ± 0.32	−2.68**	↑	0.93 ± 0.28	3.27***	↓	0.52	0.57
Maximum lifespan	54	8.39	2	0.015	−0.82 ± 0.26	−3.20**	↑	0.72 ± 0.24	2.96*	↓	0.64	0.66
Rate of senescence	54	11.09	2	0.004	2.56 ± 0.48	5.27***	↑	−2.52 ± 0.48	−5.23***	↓	< 0.01	0.41
Onset of senescence	54	6.73	1	0.010	−0.72 ± 0.25	2.91**	↑	—	—	—	< 0.01	0.21
Generation time	61	4.93	2	0.085	−0.71 ± 0.45	−1.56	—	0.95 ± 0.42	2.25*	↓	0.86	0.41

The final PGLS ANCOVA model for each life history trait is shown. Separate placenta variables are included only when they increase the fit of the data from a simple allometric model of the life history trait regressed against body mass. No final model included a contrast between either endotheliochorial or hemochorial placentas and villous and trabecular placentas; thus, these types are always combined as a single variable. Where a cell is blank, that particular placenta variable is not included in the final model because it did not improve the fit of the data. LRT represents the log-likelihood score for the final placentation model compared with a simple allometric model. The significance of this difference is tested with a χ² distribution, with df corresponding to the number of placental parameters added to the model. Arrows indicate the change in pace of life associated with the transition to epitheliochorial invasiveness and to trabecular or villous interdigitation. λ is the lambda value (the index of phylogenetic correlation), and the r² is the adjusted value.

^*P < 0.05; **P < 0.01; ***P < 0.005.