indirect costs of reproduction and the tradeoff between offspring size and number: a framework illustrated by fitness costs and benefits of ovarian fluid

Theory describing evolution of offspring size often assumes that the production cost per unit volume is the same for small and large offspring. However, this may not be true if indirect costs of reproduction (e.g., material and energetic costs of supporting offspring development) scale disproportionately with offspring size. Here we show how direct and indirect costs of reproduction can be explicitly modeled within the Smith-Fretwell framework and how observations of size-number relationships can thus be used to evaluate indirect costs. We applied this analysis to measures of egg volume and fecundity for over 300 individuals of a coastal fish species and found that the tradeoff was much stronger than the expected inverse (fecundity scaled with volume-1.843). Larger offspring were thus more expensive to produce. For our study species, an important indirect cost was that larger eggs were accompanied by disproportionately more ovarian fluid. Calorimetry and removal experiments were used to..., , , # Data from: indirect costs of reproduction and the tradeoff between offspring size and number: a framework illustrated by fitness costs and benefits of ovarian fluid

[https://doi.org/10.5061/dryad.ksn02v7ch](https://doi.org/10.5061/dryad.ksn02v7ch)

## Description of the data and file structure

*California Grunion egg size number.csv* file contains data on egg size and batch fecundity of California Grunion

(*Leuresthes tenuis*). SL is standard length in cm; Wt is weight in grams; mean.egg.diameter is measured in mm; sd and n refer to standard deviation and number in the sample used to estimate the mean diameter. n/a indicates no data.

*California Grunion egg weight and energy content.csv* file contains data on size and energy content of groups of eggs.

Separate samples of the same egg batch were made to measure weight (wet and dry) and energy content (measured via calorimetry).

Diameter of eggs is measured in mm. 'avg.E' is mean energy content (calories per gram dry weight). n/...