Interacting effects of identity, size, and winter severity determine temporal consistency of offspring phenotype

Abstract

Offspring size can strongly influence offspring fitness; however, the importance of female identity to offspring size determination is poorly understood, despite the potential for identity effects to drive offspring size adaptation and population dynamics. We tracked reproductive investment (skein mass) and mean egg diameter, mass, and density produced by individual female yellow perch (Perca flavescens) over four spawning years to determine the influences of maternal identity, size, and winter severity to reproductive trait variation. Individual identity significantly influenced egg diameter and mass, but did not affect egg density or skein mass. All egg traits were negatively influenced by winter severity prior to spawning, and egg mass and diameter were also negatively related to maternal size. Our results suggest that individual effects can comprise a large amount of the intrapopulation variation in reproductive traits in populations, which may be unaccounted for in studies examining only environmental or phenotypic effects. Accounting for potential identity effects would likely improve our understanding of constraints on offspring size plasticity and potential responses of offspring size in populations experiencing environmental change.