Variation in the NP/Ne ratio as a function of the male:female sex ratio in populations that are otherwise ideal. Values in the table show total numbers of males and females, M:F sex ratio, expected numbers of each sex that produce at least one offspring (Male NP, Female NP), effective population size (Ne), and the overall NP/Ne ratio across both sexes. Expected NP was calculated using the dbinom function in R to predict the number of null parents, and Ne was calculated using Wright’s formula Ne = 4*Males*Females/(Males + Females). As the sex ratio becomes more female biased, female Np increases almost linearly with the number of females, whereas overall Ne is increasingly constrained by the asymptotic value of Ne = 4*Males. As a consequence, the ratio Np/Ne more than doubles when sex ratio changes from 1:1 to 1:10
| Males . | Females . | Sex ratio . | Male NP . | Female NP . | N P . | N e . | N P/Ne . |
|---|---|---|---|---|---|---|---|
| 50 | 50 | 1:1 | 43.4 | 43.4 | 86.7 | 100.0 | 0.87 |
| 50 | 100 | 1:2 | 47.6 | 77.9 | 125.4 | 133.3 | 0.94 |
| 50 | 150 | 1:3 | 49.1 | 110.6 | 159.8 | 150.0 | 1.07 |
| 50 | 200 | 1:4 | 49.7 | 142.9 | 192.6 | 160.0 | 1.20 |
| 50 | 250 | 1:5 | 49.9 | 174.9 | 224.8 | 166.7 | 1.35 |
| 50 | 300 | 1:6 | 50.0 | 206.8 | 256.7 | 171.4 | 1.50 |
| 50 | 350 | 1:7 | 50.0 | 238.6 | 288.5 | 175.0 | 1.65 |
| 50 | 400 | 1:8 | 50.0 | 270.3 | 320.3 | 177.8 | 1.80 |
| 50 | 450 | 1:9 | 50.0 | 302.0 | 352.0 | 180.0 | 1.96 |
| 50 | 500 | 1:10 | 50.0 | 333.7 | 383.7 | 181.8 | 2.11 |
| Males . | Females . | Sex ratio . | Male NP . | Female NP . | N P . | N e . | N P/Ne . |
|---|---|---|---|---|---|---|---|
| 50 | 50 | 1:1 | 43.4 | 43.4 | 86.7 | 100.0 | 0.87 |
| 50 | 100 | 1:2 | 47.6 | 77.9 | 125.4 | 133.3 | 0.94 |
| 50 | 150 | 1:3 | 49.1 | 110.6 | 159.8 | 150.0 | 1.07 |
| 50 | 200 | 1:4 | 49.7 | 142.9 | 192.6 | 160.0 | 1.20 |
| 50 | 250 | 1:5 | 49.9 | 174.9 | 224.8 | 166.7 | 1.35 |
| 50 | 300 | 1:6 | 50.0 | 206.8 | 256.7 | 171.4 | 1.50 |
| 50 | 350 | 1:7 | 50.0 | 238.6 | 288.5 | 175.0 | 1.65 |
| 50 | 400 | 1:8 | 50.0 | 270.3 | 320.3 | 177.8 | 1.80 |
| 50 | 450 | 1:9 | 50.0 | 302.0 | 352.0 | 180.0 | 1.96 |
| 50 | 500 | 1:10 | 50.0 | 333.7 | 383.7 | 181.8 | 2.11 |
Variation in the NP/Ne ratio as a function of the male:female sex ratio in populations that are otherwise ideal. Values in the table show total numbers of males and females, M:F sex ratio, expected numbers of each sex that produce at least one offspring (Male NP, Female NP), effective population size (Ne), and the overall NP/Ne ratio across both sexes. Expected NP was calculated using the dbinom function in R to predict the number of null parents, and Ne was calculated using Wright’s formula Ne = 4*Males*Females/(Males + Females). As the sex ratio becomes more female biased, female Np increases almost linearly with the number of females, whereas overall Ne is increasingly constrained by the asymptotic value of Ne = 4*Males. As a consequence, the ratio Np/Ne more than doubles when sex ratio changes from 1:1 to 1:10
| Males . | Females . | Sex ratio . | Male NP . | Female NP . | N P . | N e . | N P/Ne . |
|---|---|---|---|---|---|---|---|
| 50 | 50 | 1:1 | 43.4 | 43.4 | 86.7 | 100.0 | 0.87 |
| 50 | 100 | 1:2 | 47.6 | 77.9 | 125.4 | 133.3 | 0.94 |
| 50 | 150 | 1:3 | 49.1 | 110.6 | 159.8 | 150.0 | 1.07 |
| 50 | 200 | 1:4 | 49.7 | 142.9 | 192.6 | 160.0 | 1.20 |
| 50 | 250 | 1:5 | 49.9 | 174.9 | 224.8 | 166.7 | 1.35 |
| 50 | 300 | 1:6 | 50.0 | 206.8 | 256.7 | 171.4 | 1.50 |
| 50 | 350 | 1:7 | 50.0 | 238.6 | 288.5 | 175.0 | 1.65 |
| 50 | 400 | 1:8 | 50.0 | 270.3 | 320.3 | 177.8 | 1.80 |
| 50 | 450 | 1:9 | 50.0 | 302.0 | 352.0 | 180.0 | 1.96 |
| 50 | 500 | 1:10 | 50.0 | 333.7 | 383.7 | 181.8 | 2.11 |
| Males . | Females . | Sex ratio . | Male NP . | Female NP . | N P . | N e . | N P/Ne . |
|---|---|---|---|---|---|---|---|
| 50 | 50 | 1:1 | 43.4 | 43.4 | 86.7 | 100.0 | 0.87 |
| 50 | 100 | 1:2 | 47.6 | 77.9 | 125.4 | 133.3 | 0.94 |
| 50 | 150 | 1:3 | 49.1 | 110.6 | 159.8 | 150.0 | 1.07 |
| 50 | 200 | 1:4 | 49.7 | 142.9 | 192.6 | 160.0 | 1.20 |
| 50 | 250 | 1:5 | 49.9 | 174.9 | 224.8 | 166.7 | 1.35 |
| 50 | 300 | 1:6 | 50.0 | 206.8 | 256.7 | 171.4 | 1.50 |
| 50 | 350 | 1:7 | 50.0 | 238.6 | 288.5 | 175.0 | 1.65 |
| 50 | 400 | 1:8 | 50.0 | 270.3 | 320.3 | 177.8 | 1.80 |
| 50 | 450 | 1:9 | 50.0 | 302.0 | 352.0 | 180.0 | 1.96 |
| 50 | 500 | 1:10 | 50.0 | 333.7 | 383.7 | 181.8 | 2.11 |
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