Andrew H. Knoll and N. Michelle Holbrook NSF Grant NSF 0106816
Developmental biologists study processes that give rise to form in plants and animals. Paleontologists are interested in development, as well, because variations in developmental patterning must fuel the changes in form documented by the fossil record. Plant fossils are uniquely well suited for the synthesis of developmental and paleontological perspectives on morphology. Plant cell walls constrain developmental pathways, and walls preserved in fossils record patterns of growth and development in ancient plants. Further, the requirements for photosynthesis have resulted in the repeated evolution of functionally and morphologically similar structures in plants through time. Studies of living plants suggest that universal relationships exist between particular leaf forms (including leaf shape and venation patterns) and developmental dynamics. To date, however, this relationship has been probed in only a limited number of plants. PIs will examine leaf development in all living groups with laminar leaves, particularly a variety of fern lineages, to determine the level of correlation between basic characteristics of venation patterns (which can be recovered from fossils) and growth dynamics. They will track the growth hormone auxin in growing leaves to determine the extent to which its important role in vascular patterning is conserved across all plants, and compare developmental aberrations in fossil and extant leaves as an independent test of the developmental similarity of leaves with similar form. Their goal is to produce a new developmental framework for interpreting the rich fossil record of leaf evolution.
