The influence of variation in female fecundity on effective population size

摘要: Abstract Understanding the relationship between effective population size ( N e ) and number of adults in a is important for predicting genetic change small populations. In general, expected to be close /2, i.e. range /4–3 /4, provided that powerful effect bottlenecks on reducing factored out (using harmonic mean N). However, some very low published estimates / have been underestimated. Here one such factor, variation female fecundity, investigated. Its depends standardized variance fecundity (per breeding season), measure generally independent fecundity. Empirical this from 16 animal studies yielded an average value 0·44, maximum less than 1·5. To investigate values, three kinds were modelled: random (seasonal); individual; age-related. Fixed individual differences among females reduce most. /10, resulting must usually 10 or more. Random need even larger achieve same reduction. One possible mechanism, loss whole families, requires high family mortality (90% more). The third model, increases linearly with age, ineffective at causing marked decrease . Given finding unusual conditions are required below examined critically: lowest ratio, natural oysters, was found questionable because immigration into by cultivated oysters.