Electronic supplementary material for
Offspring fitness varies with parental extra-pair status in song sparrows, Melospiza
melodia
Rebecca J. Sardell, Peter Arcese and Jane M. Reid
1)
Diagram of fitness measures and relationships
mixed paternity brood 2:
mixed paternity brood 1:
extra-pair male
focal polyandrous female
♂
socially paired male
♀
EPY
♀A
♀A
♀F ♀G
♂B
♂E
♂
♂
WPY
♂C
♀D
♂C ♀D + ♂E
♀H ♂I ♂J
i) survival to recruitment
♀F
♂I ♂J
ii) hatched offspring
♀♂
♀
♀♂♀
♀ ♀
iii) recruited offspring
1
Figure S1 Variation in fitness of a focal polyandrous female’s grandoffspring (hatchlings FJ) was analysed with respect to their parents’ extra-pair status (individuals A-E). Fitness
was measured as: i) survival to recruitment, ii) lifetime probability of having ≥1 hatched
genetic offspring and iii) lifetime probability of having ≥1 recruited genetic offspring. Only
hatchlings whose mother and father were both from mixed paternity broods (e.g.
hatchlings I and J from parents D and E) were included. Dashed and solid lines represent
an individual’s survival and reproductive success. Grey lines represent instances where
individuals did not survive or reproduce.
2
2) Sample size
Table S1 Sample sizes for analyses comparing i) survival to recruitment and ii) the
probability of having ≥1 hatched or recruited offspring between hatchlings with mothers
and social or genetic fathers that were themselves extra-pair young (EPY) or within-pair
young (WPY).
mother
extra-pair status
i)
ii)
EPY
WPY
total
EPY
WPY
total
social father
extra-pair status
EPY
53
83
136
32
44
76
grand total
WPY
16
48
64
0
40
40
200
116
genetic father
extra-pair status
EPY
56
82
138
28
47
75
grand total
WPY
14
67
81
4
53
57
219
132
3
3) Supplementary analyses of hatchling extra-pair status and sex
Chi-squared tests were used to test whether EPY or WPY parents produced more male than
female hatchlings, or EPY than WPY, thereby potentially confounding analyses of variation in
hatchling fitness components with respect to parental extra-pair status (tables S2 and S3).
The proportion of hatchlings that were themselves EPY was similar across the three
parental extra-pair status groups (two WPY parents, one EPY parent, two EPY parents) in three
of four datasets. In the fourth dataset (describing hatchling recruitment with respect to social
father extra-pair status) the proportion of EPY hatchlings was smaller when both parents were
WPY, but not significantly so (table S2).
The proportion of hatchlings that were EPY was similar in seven of eight comparisons of
EPY and WPY mothers and fathers (electronic supplementary material, table S3). In the eighth
comparison (for the dataset describing the probability of having ≥1 offspring given genetic
father status) more hatchlings were EPY for WPY fathers than for EPY fathers, but not
significantly so given multiple comparisons (table S3). The proportion of male hatchlings was
similar in all three parental extra-pair status groups, and between EPY and WPY mothers and
fathers, for all four datasets (tables S2 & S3).
4
Table S2 The number (n) and percentage (%) of hatchlings that were extra-pair young (%EPY) or males (%male) and had two withinpair young (WPY) parents (WP/WP), one EPY parent and one WPY parent (WP/EP) and two EPY parents (EP/EP). Bonferronicorrected p-values (p) and chi-squared test statistics (χ2) indicate whether the proportion of hatchlings that were EPY or male varied
significantly with their parent’s extra-pair status. Data are presented for all four datasets analysed: i) and ii) probability of survival to
recruitment with social and genetic father extra-pair status respectively; iii) and iv) probability of having ≥1 offspring with social and
genetic father extra-pair status respectively.
dataset
Offspring extra-pair status (% EPY)
Offspring sex (% male)
WP/WP
WP/EP
EP/EP
WP/WP
WP/EP
EP/EP
parents
parents
parents
parents
parents
parents
total
n
%
n
%
n
%
χ2
p
n
%
n
%
n
%
χ2
p
n
i)
3/48
6%
24/99
24%
11/53
21%
6.94
0.12
21/48
44
56/99
57
31/53
59
2.72
1.00
200
ii)
22/67
33%
21/96
22%
14/56
25%
2.50
1.00
30/67
45
57/96
59
32/56
57
3.63
0.64
219
iii)
3/40
8%
6/44
14%
8/32
25%
4.41
0.44
18/40
45
24/44
55
18/32
56
1.13
1.00
116
iv)
16/53
30%
13/51
25%
4/28
14%
2.48
1.00
23/53
43
30/51
59
17/28
61
3.33
0.76
132
5
Table S3 The number (n) and percentage (%) of hatchlings that were extra-pair young (%EPY) or males (%male) with extra-pair young (EPY) or
within-pair young (WPY) mothers and fathers. Bonferroni-corrected p-values (p) and chi-squared test statistics (χ2) indicate whether the proportion
of hatchlings that were EPY or male differed significantly between EPY and WPY mothers or fathers. Data are presented for all four datasets
analysed: i) and ii) probability of survival to recruitment with social and genetic father extra-pair status respectively; iii) and iv) probability of having
≥1 hatched or recruited offspring with social and genetic father extra-pair status respectively.
dataset
Offspring extra-pair status (% EPY)
EPY
mother
Offspring sex (% male)
WPY
mother
EPY
father
WPY
father
EPY
mother
total
WPY
mother
EPY
father
WPY
father
n
%
n
%
χ2
p
n
%
n
%
χ2
p
n
%
n
%
χ2
p
n
%
n
%
χ2
p
n
i)
17/69
25
21/131
16
1.65
0.80
29/136
21
9/64
14
1.06
1.00
39/69
57
69/131
53
0.14
1.00
79/136
58
29/64
45
2.37
0.48
200
ii)
18/70
26
39/149
26
0.00
1.00
31/138
22
26/81
32
1.99
0.64
40/70
57
79/149
53
0.18
1.00
81/138
59
38/81
47
2.40
0.48
219
iii)
8/32
25
9/84
11
2.73
0.40
14/76
18
3/40
8
1.70
0.76
18/32
56
42/84
50
0.16
1.00
42/76
55
18/40
45
0.73
1.00
116
iv)
8/32
25
25/100
25
1.34
1.00
13/75
17
20/57
35
4.54
0.12
19/32
59
51/100
51
0.39
1.00
45/75
60
25/57
44
2.77
0.40
132
6