Abstract Detail

Genetics Section

Jobson, Richard [1], Nielsen, Rasmus [2], Laakkonen, Liisa [3], Marten, Wikstrom [3], Albert, Victor A. [4].

Positive Selection And The Molecular Evolutionary Energetics Of Active Suction Trapping In A Carnivorous Plant.

Most attention in the study of adaptation of organismal form has centered on developmental regulation. The homologous bovine protein structure of COX suggests that the residues hit by radical, positively selected, holoenzyme stabilizing mutations in the carnivorous plant lineage Utricularia, bladderworts, interact with homologues of the nuclear-encoded subunits VIIa and VIIc, which are involved in cytochrome c docking near the active CuA site of COX and enhancement of its electron transfer rate. Bladderworts trap plankton when water-immersed, negatively-pressured suction bladders are triggered. The reseting of traps involves an active ion pumping mechanism that requires considerable energy expenditure. Although the highly conserved respiratory machinery of eukaryotic cells is a seemingly unlikely target for selection that supports novel morphologies, we demonstrate that a dramatic molecular evolutionary rate increase in the principal subunit of mitochondrial cytochrome c oxidase (COX I) is caused by positive darwinian selection. Thus, the key adaptation in bladderworts arguably lies in the molecular evolutionary changes that have stabilized developmental evolution. Examples of convergent COX evolution in animal heart evolution and in expansion of the hominid neocortex underscore the fact that developmental regulatory changes may not be independently adaptive.

1 - Cornell University, Department of Plant Biology, Tower Road, Ithaca, New York, 14853-5908, USA
2 - Cornell University, Department of Biological Statistics and Computational Biology, Ithaca, New York, 14853, USA
3 - University of Helsinki, Institute of Biotechnology, Helsinki Bioenergetics Group, Programme for Structural Biology and Biophysics, Biocenter 3 (Viikinkaari 1), PB 65, Helsinki, FIN-00014, Finland
4 - University of Oslo, The Natural History Museums and Botanical Garden, P.O. Box 1172 Blindern, Oslo, NO-0318, Norway

Keywords:
Carnivorous plant
Utricularia
Ion transport
COXI
Evolution
Positive Darwinian selection
Respiration.

Presentation Type: Paper
Session: 53-11
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 3:45 PM
Abstract ID:870