Skewed distributions of LRS: beyond mean and variance

Abstract

AbstractMany field studies find that lifetime reproductive success (LRS) is highly skewed and often multimodal among individuals. Field biologists generate invaluable data on survival and reproductive rates, as a function of age and stage, that are used to parameterise structured models. These models often perform well at predicting population growth and mean LRS, but we do not know whether they accurately predict observed distributions of individual LRS. If the models fail to recreate these distributions, their use may be limited because the LRS is central to understanding life history evolution. We present powerful tools to generate distributions of LRS from age and/or stage structured models. Our methods reveal that structured models do perform well at generating distributions that agree with observations. Our approach also reveals why such skewed distributions arise, and helps resolve a debate about detecting signatures of selection in skewed distributions of LRS.