Authors: Amanda K Pettersen, Craig R White and Dustin J Marshall
Published in: Proceedings of the Royal Society B, volume 282, issue 1819 (November 2015)
Within species, larger offspring typically out-perform smaller offspring. While the relationship between offspring size and performance is ubiquitous, the cause of this relationship remains elusive.
By linking metabolic and life-history theory, we provide a general explanation for why larger offspring perform better than smaller offspring. Using high-throughput respirometry arrays, we link metabolic rate to offspring size in two species of marine bryozoan.
We found that metabolism scales allometrically with offspring size in both species: while larger offspring use absolutely more energy than smaller offspring, larger offspring use proportionally less of their maternally derived energy throughout the dependent, non-feeding phase. The increased metabolic efficiency of larger offspring while dependent on maternal investment may explain offspring size effects—larger offspring reach nutritional independence (feed for themselves) with a higher proportion of energy relative to structure than smaller offspring.
These findings offer a potentially universal explanation for why larger offspring tend to perform better than smaller offspring but studies on other taxa are needed.
Pettersen AK, White CR, Marshall DJ (2015) Why does offspring size affect performance? Integrating metabolic scaling with life-history theory. Proceedings of the Royal Society B, 282: 20151946. PDF 771 KB LINK doi:10.1098/rspb.2015.1946