The use of phylogenetic perspective in comparative plant physiology and developmental biology

The use of phylogenetic reconstruction for the testing of comparative hypotheses is a recent development in the fields of plant physiology and developmental biology. In this review, several uses of phylogenetic information are discussed, including (1) the use of phylogenetic trees for choosing experimental systems, (2) justifying the statistical independence of compared taxonomic groups, (3) identifying evolutionary direction using outgroup analysis, and (4) studying the evolutionary tempo of physiological and developmental change. Difficulties are also discussed, especially with respect to (1) mapping continuous, physiological traits onto the discrete, binary structure of phylogenetic trees, (2) constructing trees from traits that are independent of the physiological and developmental characters being mapped, and (3) respecting the statistical nature of phylogenetic trees. The bulk of the review is devoted to several examples from the literature that illustrate the power of a phylogenetic perspective in comparative studies. Reviewed examples include (1) elucidation of a novel pyrophosphate- dependent phosphofructokinase in the glycolytic pathway of phosphate- stressed plants in the Brassicaceae, (2) evolutionary pattern in the origins of polyploid endosper in angiosperm, (3) adaptive radiation of Hawaiian Island plants into dry habitats, and (4) evolutionary pattern in the origins of C₄ photosynthesis. The fields of systematics, comparative physiology, and developmental biology will continue to merge as their common reliance on phylogenetic perspective increases.