Table 1.

Properties of empirical food webs (D) and corresponding properties predicted by our evolutionary model (E) and the niche model (N) (3)

	Mean error		St. Martin Island			Coachella Desert			Ythan Estuary			Chesapeake Bay			Bridge Brook Lake			Little Rock Lake			Skipwith Pond
Value	E	N	E	N	D	E	N	D	E	N	D	E	N	D	E	N	D	E	N	D	E	N	D
Connectance, %	99	Parameter	0.26	*	0.12	0.26	*	0.31	0.23	*	0.061	0.24	*	0.072	0.2	*	0.17	0.15	*	0.12	0.27	*	0.32
			(116)			(16)			(277)			(233)			(15)			(25)			(15)
Chain length, %	26	35	4.15	5.76	4.2	6.2	6.95	7.18	3.79	6.39	4.89	4	3.28	2.77	4.14	4.86	2.55	4.6	**	**	5.44	6.23	4.81
			(1)	(37)		(14)	(3)		(22)	(31)		(44)	(18)		(62)	(91)					(13)	(30)
Omnivore, %	19	22	54	63	60	76	75	79	42	61	53	46	42	38	48	61	36	47	**	**	74	77	60
			(10)	(5)		(4)	(5)		(22)	(15)		(21)	(11)		(33)	(69)					(23)	(28)
Top, %	22	52	17	9	17	5	6	0	24	8	38	21	14	28	4	10	0	4	5	0	5	6	4
			(0)	(47)					(37)	(79)		(25)	(50)								(25)	(33)
Intermediate, %	7	10	63	75	69	80	86	90	55	74	53	60	60	62	68	73	68	82	85	87	79	85	92
			(9)	(9)		(11)	(4)		(4)	(40)		(3)	(3)		(0)	(7)		(6)	(2)		(14)	(8)
Bottom, %	75	60	20	17	14	15	9	10	21	18	9	19	26	10	28	17	32	14	10	13	16	9	4
			(43)	(21)		(50)	(10)		(22)	(33)		(90)	(160)		(13)	(47)		(8)	(23)		(300)	(125)

For comparison, the relative errors of the two models are indicated between parentheses. See Model and Methods for computation of these properties. Empirical data are from Cattin et al. (4).

^*Connectance is a parameter of the niche model, not a result.

^**Not available.