Figure 8.3 Offspring number versus offspring size. Among 14 populations and species of goldenrod plants, individuals that produce more seeds also produce smaller seeds, demonstrating that a trade-off exists between the two life history traits.
Data from P. A. Werner and W. J. Platt. Ecological relationships of co-occurring goldenrods (Solidago: Compositae), The American Naturalist 110 (1976): 959–971.