Inbreeding depression in red deer calves

Table 2 Minimal generalised linear mixed models of birth date and offspring birth weight.

	Birth date (N = 2515 calves, 602 mothers)			Birth weight (N = 1664 calves, 487 mothers)
Random effects	Variance ± SE	p		Variance ± SE	p
Mother ID	26.29 ± 4.67	<0.001		0.626 ± 0.231	<0.001
Year of birth (YOB)	8.46 ± 2.58	<0.001		0.0461 ± 0.0170	<0.001
YOB*Offspring F	0 ^B	1		2.04 ± 8.15	0.775
YOB*Mother's F	0 ^B	1		0 ^B	1
Residual	267.8 ± 8.53	<0.001		0.707 ± 0.260	<0.001
Fixed effects	Estimate ± SE	Wald F _df	p	Estimate ± SE	Wald F _df	p
Mother's age	-2.55 ± 0.67	14.53_1,2489	<0.001	0.394 ± 0.050	61.50_1,1454	<0.001
Mother's age²	0.154 ± 0.033	21.39_1,2493	<0.001	-0.0224 ± 0.0025	77.48_1,1440	<0.001
Mother's status^a TY	-7.35 ± 0.94	25.56_4,2472	<0.001	0.616 ± 0.067	34.11_4,1439	<0.001
N	-5.30 ± 1.47			0.0236 ± 0.104
SY	-10.12 ± 1.19			0.559 ± 0.087
WY	-1.42 ± 1.34			-0.157 ± 0.086
Birth weight	NF			NF
Birth date	NF			0.0131 ± 0.0021	39.08_1,1564	<0.001
Population size	-0.139 ± 0.035	15.76_1,28	<0.001	0.00277 ± 0.00286	0.94 _1,31	0.340
Sex^b	0.301 ± 0.765	0.15 _1,1719	0.689	0.358 ± 0.047	59.27_1,1405	<0.001
Environmental variable	0.0171 ± 0.0074^c	5.35_1,27	0.029	0.181 ± 0.065^d	7.79_1,33	0.009
Offspring F	3.26 ± 13.7	0.06 _1,1345	0.805	-2.325 ± 0.983	5.6_1,1507	0.019
Mother's F	42.5 ± 30.5	1.95 _1,318	0.166	3.33 ± 3.28	1.03 _1,405	0.312

NF term not fitted in model. ^aReference for mother's status is milk (M) hinds. ^bReference level for sex is females. ^cAutumn rainfall, ^dSpring temperature. ^BBound at zero. Final models were achieved by sequentially dropping the least significant terms based on Wald statistics until only significant terms remained. Denominator degrees of freedom are calculated numerically using a Kenward and Roger adjustment in ASReml [88]. Text in italics indicates non-significant parameters and their associated estimates and significance at removal (see methods for details). N = sample sizes for minimal models.

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