An evaluation of factors that could lower the genetic effective size to adult census size ratio (Ne/N) in red drum (Sciaenops ocellatus)

Deviation from
idealized population
Predicted effect on
Ne/N (with respect to
idealized population)
Observation or statistical testHypothesized
effect on
observed Ne/N?
Fluctuating population sizeDecreaseN (1987) ≈ N (1998); temporal method Ne ≈ coalescent method NeSmall
Biased sex ratioDecreaseSex ratio does not deviate from 1:1 (P = 0.52; t-test)Small
Nondiscrete (i.e., overlapping) generationsIncreaseCorrection increases Ne by factor of 4.81Small
Population structure (migration-drift equilibrium with local inbreeding)DecreaseNe/N = 0.96 when F-statistics were substituted into equilibrium modelsSmall
Metapopulation structure (with variance in productivity among demes)DecreaseSee textLarge
Variance in reproductive success among individualsDecreaseP = 0.00007 required to solve for observed Ne/N; unrealistically small Small
Variance in productivity among demesDecreaseP = 0.058 required to solve for observed Ne/N, provided that variance in productivity is equal to variance in individual reproductive successLarge