PHYLOGENETIC PATTERN AND DEVELOPMENTAL PROCESS IN DROSOPHILA

Recent molecular and morphological results on the phylogenetics of Dro sophila and other Drosophilidae are reviewed. There is some consensus on the redefinition of Drosophila to make it a monophyletic group, exc ept for the controversial placement of the Hawaiian Drosophila and the subgenus Sophophora. The possibility of Hawaiian Drosophila as a grou p that is morphologically atavistic (e.g., with many character reversa ls) is discussed. Drosophila development is reviewed, with focus on un derstanding the developmental genetic and molecular bases of character convergence and reversal in drosophilid phylogenetics and its applica tions to homology decisions. The clustering of convergent characters o n cladograms is discussed as a consequence of developmental constraint s. The convergent evolution of broadened head shape in male drosophili ds is presented as an example. Molecular and developmental analysis of homoplastic characters pivotal to phylogenetic schemes, such as eye s etae in Drosophila sensu stricto and the Hawaiian species, can be of f undamental importance for homology assessment.