ABSTRACT
Cell size plays a role in body size evolution and environmental adaptations. Addressing these roles, we studied body mass and cell size in Galliformes birds and Rodentia mammals, and collected published data on their genome sizes. In birds, we measured erythrocyte nuclei and basal metabolic rates (BMRs). In birds and mammals, larger species consistently evolved larger cells for five cell types (erythrocytes, enterocytes, chondrocytes, skin epithelial cells, and kidney proximal tubule cells) and evolved smaller hepatocytes. We found no evidence that cell size differences originated through genome size changes. We conclude that the organism-wide coordination of cell size changes might be an evolutionarily conservative characteristic, and the convergent evolutionary body size and cell size changes in Galliformes and Rodentia suggest the adaptive significance of cell size. Recent theory predicts that species evolving larger cells waste less energy on tissue maintenance but have reduced capacities to deliver oxygen to mitochondria and metabolize resources. Indeed, birds with larger size of the abovementioned cell types and smaller hepatocytes have evolved lower mass-specific BMRs. We propose that the inconsistent pattern in hepatocytes derives from the efficient delivery system to hepatocytes, combined with their intense involvement in supracellular function and anabolic activity.
Footnotes
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: W.M.K., J.K.; Methodology: M.C., A.M.L., T.P., W.M.K., J.K.; Software: F.K.; Validation: M.C., A.M.L., F.K.; Formal analysis: M.C.; Investigation: A.M.L., D.D.-K., T.P., K.P.; Data curation: A.M.L., F.K.; Writing - original draft: M.C.; Writing - review & editing: M.C., A.M.L., D.D.-K., T.P., K.P., F.K., W.M.K., J.K.; Supervision: J.K.; Project administration: J.K.; Funding acquisition: J.K.
Funding
The research was supported by the Polish Ministry of Scientific Research and Information Technology [1720/B/P01/2009/36] and funds from the Institute of Environmental Sciences Jagiellonian University [DS/BINOZ/INOS/757/2018]. The development of TOCS was supported by the Polish National Science Center [2016/21/B/NZ8/00303].
Supplementary information
Supplementary information available online at http://bio.biologists.org/lookup/doi/10.1242/bio.029603.supplemental
- Received September 6, 2017.
- Accepted March 7, 2018.
- © 2018. Published by The Company of Biologists Ltd
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.