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Insect egg size and shape evolve with ecology but not developmental rate


Over the course of evolution, organism size has diversified markedly. Changes in size are thought to have occurred because of developmental, morphological and/or ecological pressures. To perform phylogenetic tests of the potential effects of these pressures, here we generated a dataset of more than ten thousand descriptions of insect eggs, and combined these with genetic and life-history datasets. We show that, across eight orders of magnitude of variation in egg volume, the relationship between size and shape itself evolves, such that previously predicted global patterns of scaling do not adequately explain the diversity in egg shapes. We show that egg size is not correlated with developmental rate and that, for many insects, egg size is not correlated with adult body size. Instead, we find that the evolution of parasitoidism and aquatic oviposition help to explain the diversification in the size and shape of insect eggs. Our study suggests that where eggs are laid, rather than universal allometric constants, underlies the evolution of insect egg size and shape.

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Data availability

The dataset of insect eggs is publicly available at Dryad ( with doi:10.5061/dryad.pv40d2r and has been described elsewhere24. The phylogenetic posterior distributions are provided as Supplementary Information (phylogeny_posterior distribution_misof_backbone.nxs and phylogeny_posterior_distribution_rainford_backbone.nxs).

Code availability

All code required to reproduce the analyses and figures shown here is available at


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This work was supported by the National Science Foundation (NSF) under grant no. IOS-1257217 to C.G.E., NSF GRFP DGE1745303 to S.H.C. and by a Jorge Paulo Lemann Fellowship to B.A.S.d.M. from Harvard University. We thank members of the Extavour laboratory and B. Farrell, C. Dunn, D. McCoy, D. Rice, A. Kao, E. Kramer, J. Boyle, L. Bittleston, M. Srivastava, M. Johnson, P. Wilton, R. Childers and S. Prado-Irwin for discussion, and the Ernst Mayr Library at the Museum of Comparative Zoology at Harvard, and specifically M. Sears, for assistance in gathering references.

Reviewer information

Nature thanks Clay Cressler and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Author information

S.H.C. and S.D. conceived the project and generated the dataset. S.H.C. performed statistical analyses. B.A.S.d.M. performed phylogenetic analyses. All authors contributed to experimental design, interpretation and writing.

Correspondence to Samuel H. Church or Cassandra G. Extavour.

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Supplementary information

Supplementary Information

This document contains Supplementary Methods, Supplementary Figures S1-S24, and Supplementary Tables S1-S22. These provide additional methodological details, a more complete description of the diversity of insect eggs, ancestral state reconstructions, and evolutionary model fitting results.

Reporting Summary

Supplementary Information

This file contains the Egg Dataset Bibliography. This document is a list of the 1,756 published sources that were used to generate the assembled dataset of insect egg traits.

Supplementary Information

This nexus file contains 100 phylogenetic trees randomly sampled from the posterior distribution, assembled using the Rainford et al. 2014 (ref. 26 in the main text) phylogeny as a backbone.

Supplementary Information

This nexus file contains 100 phylogenetic trees randomly sampled from the posterior distribution, assembled using the Misof et al. 2014 (ref. 25 in the main text) phylogeny as a backbone.

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Fig. 1: The shapes and sizes of hexapod eggs.
Fig. 2: The allometric relationship of egg shape and size evolves across insects.
Fig. 3: Developmental features do not co-vary with egg size.
Fig. 4: Shifts in oviposition ecology are associated with changes in egg morphology.


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