Supplementary Information S1: Population history and development of the pedigree
Vega was colonized by 3 moose in 1985 following centuries of absence (most likely present
in pre-historic times, but likely exterminated by early settlers). Mark and re-capture was
performed each year from 1992 to 2012 [1,2], except in 2003 and 2008. All mature females
were tissue-sampled except one, which was present as a potential mother two years. Only six
potentially reproducing Vega-born males were not sampled (life spans; 1986-1990, 19871990, 1991-1993, 1990-1991, 1992-1993 and 1993-1994, as well as one immigrant male
(present 2007). The first of these males only had one possible mother and father. The second
had the same only potential father and two potential mothers, of which we assumed the oldest
3.5 years old cow as mother. Therefore, for seven calves born in 1990 and 1991 for which the
only sampled adult male was excluded as a father, an arbitrary choice was made among these
two un-sampled males as a father in the pedigree (significantly assigned mothers, similar
inbreeding coefficient).
From observational data since 1992, a social mother was assumed for 284 of the 445
recorded moose on Vega. Among calves with a social mother, 268 were significantly assigned
to a parent-pair and only 19 (7%) of these did not match the social mother. We therefore
accepted the social maternity of 7 non-significantly assigning calves and the assigning sire, as
well as the social maternity of 25 un-sampled calves with a sampled twin and accepted as
father the male assigned to the twin. Twenty five un-sampled calves with known social
mother could not get assigned a father and were excluded from the analyses.
For fifteen suspected immigrants and five additional individuals sampled as adults, no
parent-pairs or maternities assigned (negative LOD) or matched any year, and these were
subsequently treated as immigrants (neither inbred or resulting in inbreeding). For all other
sampled individuals a father was assigned but in one case a mother could not be assigned.
In total, this resulted in a pedigree which in numbers of generations counted up to
seven for females and up to five for males.
Table S1. Yearly numbers of calves born and number of adult potential moose breeders (being
potential parents the following year), and numbers of adults and calves culled each year on
Vega between 1986 and 2010, with the included number of un-sampled individuals in
parentheses.
Year
Calves born
1985
Females present
Bulls present
Adults culled
Calves culled
1
1
0
0
1986
1
2
1
0
0
1987
3
2
2 (1)
0
0
1988
3
4
3 (2)
0
0
1989
4
5
4 (2)
2
0
1990
7
7
5 (2)
2
0
1991
9
12 (1)
6 (1)
1
1
1992
18
12 (1)
11 (1)
1
3
1993
21
13
19 (2)
14
0
1994
16
13
22 (1)
29
0
1995
15
12
9
7
4
1996
20
13
13
10
5
1997
19
17
7
6
9
1998
21
17
6
8
10
1999
26
15
7
7
12
2000
25
15
11
10
12
2001
22
17
13
11
8
2002
25
19
12
9
12
2003
26
18
12
11
12
2004
21
19
15
9
12
2005
23
18
16 (1)
9
18
2006
19
16
14 (1)
9
12
2007
23
15
13 (1)
3
15
2008
22
14
16
10
16
2009
18
17
16
8
12
Supplementary Information S2: Inbreeding avoidance models and AICc-based ranking
of candidate models
About the structure of the global model
If an interaction was included in a candidate model, its main effects were retained. Models
that included the main effect of σfMating or AgeMales and not their interactions with fMating were
not considered as candidate models as we primarily were interested in population structure on
inbreeding avoidance (measured by fMating), and not population structure on the probability of
mate.
The annual mean fMating varied over the study period. We can expect that it is the relative
fMating a giving breeding season that is important, i.e. the fMating of mates relative to other mates
the same breeding season. To test this, we calculated the relative fMating by centralising fMating
within year (i.e. subtracting annual mean from each potential breeding attempt's fMating). We
then reran the model selection, replacing fMating with the relative fMating. This did not affect the
rank of the highest ranked models, and the pattern between relative fMating and P(realisation)
was similar as for the absolute fMating. We therefore choose to use absolute fMating in the
analyses.
Table S2. AICc-based ranking of candidate models explaining probability that potential
mating events were realised. ΔAICc is the difference in AICc between a model and the
highest ranked model, whereas AICc-weights can be considered the likelihood that a model is
the true model, given that one of the candidate models is the true model [3]. Only models with
ΔAICc < 2 are shown, in addition to the highest ranked model without fMating (rank 12) and the
full model (rank 108). NAdult and ASR were included in all candidate models. For variables
explanation, see main text.
Rank
Model specification
ΔAICc
AICcweight
1
fMating + ASR + NAdult + AgeMales + fMating*ASR + fMating*NAdult +
0.00
0.082
0.08
0.079
1.31
0.043
1.46
0.040
1.67
0.036
1.76
0.034
ASR*NAdult + fMating*ASR*NAdult
2
fMating + ASR + NAdult + fMating*ASR + fMating*NAdult + ASR*NAdult +
fMating*ASR*NAdult
3
fMating + ASR + NAdult + AgeMales + fMating*ASR + fMating*NAdult +
fMating*ASR*NAdult + fMating*AgeMales
4
fMating + ASR + NAdult + fMeanMating + fMating*ASR + fMating*NAdult +
fMating*ASR*NAdult
5
fMating + ASR + NAdult + AgeMales + fMeanMating + fMating*ASR +
fMating*NAdult + fMating*ASR*NAdult
6
fMating + AgeMales + σfMating + ASR + NAdult + fMating*ASR +
fMating*NAdult + ASR*NAdult + fMating*ASR*NAdult
12
ASR * NAdult
3.29
0.016
108
fMating + fMeanMating + σfMating + ASR + NAdult + AgeMales +
8.08
0.001
fMating*fMeanMating + fMating*σfMating + fMating*ASR + fMating*NAdult +
fMating* AgeMales + ASR*NAdult + fMating*ASR*NAdult
Supplementary Information S3: Data summary of population properties inbreeding
coefficient and mating probability
Table S3. Mean (SD, N) inbreeding coefficient, fMating, based on identity-by-descent [4] for
offspring from potential mating events that were realised (resulted in offspring) and nonrealised for years with adult sex ratio (NMales/NFemales), ASR, and adult population size, NAdult,
above or below the median from the data used in the statistical models in Table S2.
fMating for realised mating
fMating for non-realised mating
events
events
Low ASR (≤ 0.8)
0.145 (SD = 0.109, N = 154)
0.148 (SD = 0.103, N = 1229)
High ASR (> 0.8)
0.106 (SD = 0.113, N = 92)
0.124 (SD = 0.103, N = 1224)
Low NAdult (≤ 30)
0.140 (SD = 0.115, N = 170)
0.135 (SD = 0.103, N = 1402)
High NAdult (> 30)
0.107 (SD = 0.100, N = 76)
0.137 (SD = 0.104, N = 1051)
References
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