American Journal of Botany Special Lecture
Rothwell, Gar .
Descent with Modification; uniting paleontology and molecular genetics to integrate pattern and process in plant evolution.
In a surprisingly simple yet elegant expression, Darwin (1859) described biological evolution as Descent with Modification. Within a developmental framework, evolution can be understood as proceeding by successive alterations of ontogeny, which are mediated via regulatory genetics and reflected by mature plant structure. Traditional paleontological practice employs transformational series of mature morphologies that track evolutionary alterations through time, for testing phylogenetic hypotheses, and for reconstructing the overall pattern of plant phylogeny. Up to the present, neither nucleotide sequences nor experimental manipulations of development have become directly available to the paleontologist for testing evolutionary hypotheses within an ontogenetic framework. Nevertheless, diagnostic structural finger prints of both plant development and developmental regulatory mechanisms are preserved in the mature morphology and anatomy of plant structures, and developmental evolutionary processes can be inferred from those structures. Polar auxin regulation of plant growth produces structural fingerprints for tropic responses, for the patterning of stellar architecture, and for secondary vascular tissue production in progymnosperms,seed plants, and arborescent lycopods. And, those fingerprints provide evidence for inferring the processes underlying parallel evolution of giant trees among lignophytes and lycophytes. Other developmental fingerprints reveal that the diagnostic structural features of fern and seed plant leaves evolved in different sequences within each clade, thus falsifying the hypothesis that megaphylls have a single origin among euphyllophytes.
Paleo-evolutionary/developmental plant biology has tremendous potential for fully integrating pattern and process in plant evolution.
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1 - Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, OR, 97330, USA
Presentation Type: Special Presentation
Location: Franklin C and D/Hyatt
Date: Monday, July 9th, 2012
Time: 11:00 AM