Darwin does it again

June 13, 2011

Darwin does it again

Development of Leaves with Dissected Lamina.  Plate from Mercklin, 1846a

Plate from Mercklin (1846a). (Image courtesy of the Botany Libraries of Harvard University.)

The name Charles Darwin is synonymous with modern evolutionary thought. While best known for advancing the theory of natural selection, Darwin had a hand in numerous areas of evolutionary biology. In the field of evolutionary developmental biology (“evo-devo”), Darwin devoted an entire chapter of On the Origin of Species (1859) to arguing that modifications during animal embryogenesis lead to morphological novelty. However, only one sentence in the book focuses on the evolution of plant form.

To trace the origin and history of plant evo-devo, Ned Friedman, director of the Arnold Arboretum and Arnold Professor of Organismic and Evolutionary Biology, and Professor Pam Diggle of the University of Colorado, combed through the historical record. The results of their investigation—published in the April issue of the journal Plant Cell—represent the first historical treatment of plant evo-devo. It should come as no surprise that their study suggests that Darwin was the first to connect the role of development to the evolution and transformation of plant form.

Behind that single sentence in On the Origin of Species lay a comprehensive knowledge of botany and an understanding of how modifications to plant form were possible. Examining Darwin’s notes, Friedman and Diggle found that Darwin had studied the work of the first comparative plant morphologists, including Duchartre and Barnéoud. Using comparative approaches and a sensitivity to detail, these early botanists discovered that even though the mature form of an organ—say a flower—can differ significantly between species, the initial form traces back to a common morphology. Yet it was Darwin who first took this idea and connected it to evolutionary principles: successive modifications lead to novel morphologies.

Friedman and Diggle’s journey through history and their clarification of the origins of plant evo-devo were made possible through the archival resources of the Horticultural Library of the Arnold Arboretum of Harvard University and other libraries around the world.

Friedman, W. E. and P. K. Diggle. 2011. Charles Darwin and the origins of plant evolutionary developmental biology. Plant Cell 23: 1-14.

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