Supplementary Material
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SUPPLEMENTAL MATERIALS AND METHODS
(a) Lifetime reproductive success
Our lifetime reproductive dataset excluded individuals that bred in either the first two breeding
seasons or the last five breeding seasons in which their social group was studied. We included all
individuals that did not breed in the first season that they were observed in a social group.
Because immigrant females likely never breed before joining a new social group and begin
breeding in the first year they arrive [1], we also included females if they had bred in the first
season in which they were observed.
(b) Genotyping
Genomic DNA was extracted from blood stored in 2% Queens Lysis buffer [2] using a DNeasy
Blood & Tissue Kit (Qiagen Inc., Valencia, CA). Sex was confirmed molecularly using
previously described methods [3]. Genotyping was performed on 3130xl, 3130, and 3100
Genetic Analyzers (Life Technologies Corp.), and all alleles were scored using Geneious v6.1
(Biomatters Limited) [4].
(c) Parentage analysis
Although nearly all birds in the population have been banded, there was an average of 0.17
unmarked males and 0.22 unmarked females per group per year that were never captured. These
values were estimated from 1-3 hour focal observations during nest building, incubation, and
nest provisioning, as well as from monthly trapping and annual censuses.
To ensure that the observed social mother was the genetic mother of all offspring, we first
conducted maternity analyses for each offspring with all possible candidate mothers. Parentage
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analysis confirmed that the social mother was the genetic mother for 99.5% of the offspring.
Captured females accounted for 575 of 578 (99.5%) offspring in the genetic dataset; one
breeding female was not captured and assumed to be the genetic mother of the remaining three
offspring. To be conservative, all males in the study population were considered as candidate
fathers. Two parentage simulations were performed for each offspring, one based on the known
mother and one based on both the known mother and the social father [sensu 4,5]. If the
genotype of the social father matched the genotype of the offspring, then it was identified as the
genetic father. If it did not, other simulations were generated to determine the most likely genetic
father among candidate males. These results were compared against behavioral observation data
to ensure that identified genetic paternal relationships were spatially and temporally feasible. We
also used 102 single nucleotide polymorphisms (SNPs) to confirm paternity assignment for a
subset of the offspring and found similar results [5].
CERVUS identified a single genetic father for 417 of 578 (72%) offspring with zero
allelic mismatches. In instances where CERVUS identified two potential candidate fathers, we
eliminated those that were less than two years of age and those that were sons of the mother
[sensu 5,6]. Paternity was assigned to the male that sired the other nestlings within the brood in
41 of 49 (84%) of cases and to an extra-pair male in the remaining eight cases. In cases where
CERVUS could not assign a candidate father and the social father was not captured, the nonsampled social father was assumed to be the genetic father (15 of 578 [2.6%] offspring) [sensu
5,6]. Thus, a genetic father was assigned to 542 of 578 (93.8%) offspring. In the 36 of 578
(6.2%) cases where CERVUS failed to assign a candidate father but where the social father was
captured, the genetic father was considered to be an extra-group male [sensu 4,5]. In summary,
the social mother was the genetic mother for 99.5% of the offspring, but 58 of 578 (10%)
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offspring were sired by an extra-pair male. Our measures of male reproductive success accounted
for both within-pair and extra-pair offspring.
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SUPPLEMENTAL RESULTS
(a) Bateman gradients for lifetime reproductive success
We repeated our Bateman gradient analyses using lifetime reproductive success instead of actual
reproductive success and found quantitatively similar results. The lifetime reproductive success
of females increased with the total number of mates (Χ248 = 7.09, P = 0.0077) while accounting
for the number of breeding seasons (Χ248 = 44.98, P < 0.0001). When considering only those
chicks that fledged, reproductive success still increased with the total number of mates (Χ248 =
8.89, P = 0.0029) while controlling for breeding season (Χ248 = 16.23, P < 0.0001). In contrast to
the patterns observed in females, the lifetime reproductive success of males did not increase with
the total number of mates (Χ233 = 0.0.08, P = 0.80) while accounting for breeding seasons (Χ233 =
38.09, P < 0.0001). Similarly, when considering only those chicks that fledged, there was no
increase in lifetime reproductive success with an increase in the total number of mates (Χ233 =
0.0094 P = 0.92) while accounting for breeding seasons (Χ233 = 28.88, P < 0.0001).
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SUPPLEMENTAL TABLES
Table S1. Opportunity for selection (I) based upon the total offspring hatched. The mean,
variance, and standardized variance in actual reproductive success are given for females (f) and
males (m) in each year of the study from 2001 to 2013. We also calculate the annual differences
in the opportunity for selection between males and females (∆I, Im-If).
n
sex
mean
var
f
62
0.78
3.07
2001
51
m
0.75
2.46
f
41
0.35
1.45
2002
m
37
0.41
1.51
f
47
0.40
1.15
2003
m
42
0.44
1.42
f
63
0.54
1.79
2004
m
59
0.60
1.64
f
36
0.31
1.14
2005
m
35
0.35
1.21
f
35
0.30
0.77
2006
m
32
0.32
0.82
f
49
0.42
1.54
2007
m
48
0.46
1.42
f
47
0.40
1.71
2008
m
42
0.39
1.31
f
37
0.31
1.40
2009
m
37
0.33
1.37
f
56
0.47
2.30
2010
m
55
0.48
2.51
f
42
0.35
1.59
2011
m
42
0.36
1.37
f
31
0.25
0.73
2012
m
31
0.26
0.83
f
29
0.24
0.64
2013*
30
m
0.26
0.69
f
44.23
0.39
1.48
mean
41.62
m
0.42
1.43
*
data for 2013 only include the long rains breeding season
year
I
4.98
4.37
11.84
9.14
7.23
7.26
6.16
4.54
12.21
10.07
8.80
8.15
8.95
6.81
10.79
8.84
14.20
12.33
10.40
10.99
12.99
10.63
11.63
11.89
10.93
10.53
10.09
8.94
∆I
-0.61
-2.70
0.03
-1.62
-2.14
-0.65
-2.14
-1.95
-1.87
0.59
-2.36
0.26
-0.40
-1.15
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Table S2. Opportunity for selection (I) based upon only those offspring that fledged. The mean,
variance, and standardized variance in actual reproductive success are given for females (f) and
males (m) in each year of the study from 2001 to 2013. We also calculate the annual differences
in the opportunity for selection between males and females (∆I, Im-If).
n
sex
mean
var
f
54
0.68
2.76
2001
43
m
0.63
2.18
f
37
0.32
1.24
2002
m
36
0.40
1.35
f
42
0.36
0.98
2003
m
39
0.41
1.31
f
43
0.37
1.11
2004
m
39
0.40
1.00
f
33
0.28
1.04
2005
m
32
0.32
1.10
f
11
0.09
0.15
2006
m
9
0.09
0.16
f
19
0.16
0.44
2007
m
20
0.19
0.50
f
29
0.25
0.84
2008
m
24
0.22
0.67
f
19
0.16
0.80
2009
m
19
0.17
0.74
f
35
0.29
1.31
2010
m
37
0.32
1.69
f
30
0.25
0.81
2011
m
27
0.23
0.71
f
23
0.19
0.44
2012
m
23
0.20
0.47
f
7
0.06
0.17
2013*
7
m
0.06
0.18
f
29.38
0.27
0.93
mean
27.31
m
0.28
0.93
*
data for 2013 only include the long rains breeding season
year
I
5.90
5.44
12.35
8.64
7.76
7.76
8.25
6.35
13.31
10.94
17.68
20.40
17.12
13.83
13.85
13.89
30.97
25.36
15.16
16.36
12.97
13.40
12.03
12.15
50.85
49.57
16.78
15.70
∆I
-0.46
-3.71
0.00
-1.90
-2.37
2.72
-3.29
0.04
-5.61
1.2
0.43
0.12
-1.28
-1.08
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2
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Griffiths, R.M., Double, M.C., Orr, K. & Dawson, R.J.G. 1998 A DNA test to sex most
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5
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6
Rubenstein, D.R. 2007 Female extrapair mate choice in a cooperative breeder: trading sex for
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