Molecules, Biodiversity, and Adaptive Evolution

The American Genetic Association (AGA) is the oldest professional society that is devoted to study the mechanisms and consequences of heredity. The AGA publishes Journal of Heredity and promotes researches in such fields as population/ecological genetics, molecular evolution, bioinformatics, developmental genetics, and physiological/ biochemical genetics (e.g., see Crow 2004). Although it is not widely known, in addition to its annual meetings, the AGA also provides financial support for other scientific meetings as well. On June 17–20, 2004, the AGA cosponsored the international meeting of ‘‘Genomes and Evolution 2004’’ with the International Society of Molecular Biology and Evolution (SMBE) at Pennsylvania State University, in State College, Pennsylvania. In this meeting, the AGA sponsored symposia on ‘‘Adaptive Evolution’’ and ‘‘Molecules and Biodiversity.’’ The AGA has a tradition of recognizing a Wilhemine E. Key Lecturer each year. Professor Walter Gehring from University of Basel in Switzerland was the recipient of the AGA 2004 Key Lecturer award and delivered a keynote lecture on ‘‘Development and Evolution of Eyes and Photoreceptors.’’ The articles collected in this volume, which are derived from oral and poster presentations at the two symposia, give us some hints about exciting new research directions on molecular diversity and adaptive evolution. In the first article, ‘‘New Perspective on Eye Development and the Evolution of Eyes and Photoreceptors,’’ Gehring shows that the master control gene, Pax 6, can induce ectopic eyes in both insects and vertebrates, arguing strongly for a monophyletic orgin of the eye. He also hypothesizes that the origin of photoreceptor cells in metazoa can be traced to a colonial protist and/or to photosynthetic cyanobacteria. In the second article on a similar subject, ‘‘Adaptive Evolution of Eye Degeneration in the Mexican Blind Cavefish,’’ W. R. Jeffery shows that Hedgehog midline signaling inhibits eye formation by inducing lens apoptosis in the Mexican blind cavefish embryos and suggests that eye degeneration in cavefish is caused by adaptive evolution. In ‘‘Phytochrome Evolution in Green and Nongreen Plants,’’ S. Mathews reviews the current level of our understanding of the evolution of light sensing molecules, photochromes, in early angiosperms, Arabidopsis, and a family of parasitic plants. In ‘‘Evolution of New Hormone Function: Loss and Gain of a Receptor,’’ D. M. Irwin and K. Wong reveal that although three glucagon receptor genes (glucagon, GLP-1, and GLP-2) have distinct functions in regulating metabolism in mammals, glucagon and GLP-1 in fish exhibit similar physiological functions by maintaining the functionally important DNA segments. In ‘‘FoxP2 in Song-Learning Birds and Vocal-Learning Mammals,’’ D. M. Webb and J. Zhang show that song-learning birds and vocal-learning whales, dolphins, and bats do not share specific amino acid substitutions, which have caused a selective sweep of speech and language development during human evolution. In ‘‘Retention of Latent Centromeres in the Mammalian Genome,’’ G. C. Ferreri, D. M. Liscinsky, J. A. Mack, M. D. B. Eldridge, and R. J. O’Neill examine the roles of centromere repositioning on the evolution of chromosome structure and syntenic order as well as theories of the permutability of centromere location within a chromosome in mammals using evidence gained in human and the tammar wallaby. In ‘‘To B or Not to B a Flower: The Role of DEFICIENS and GLOBOSAOrthologs in the Evolution of the Angiosperms,’’ L. M. Zahn, J. Leebens-Mack, C. W. dePamphilis, H. Ma, and G. Theissen review the function, phylogeny, and expression of genes involved in the DEFICIENS (DEF) and GLOBOSA (GLO) MADS-box subfamily and suggest that the original function of these genes in the angiosperm could have been different. In ‘‘The Ecological Genetics of Homoploid Hybrid Speciation,’’ B. L. Gross and L. H. Rieseberg show that ecological selection plays a major role for promoting homoploid hybrid speciation and test a set of explicit questions using the sunflower species,Helianthus deserticola. In ‘‘Spatial Dynamics and Molecular Ecology of North American Rabies,’’ L. A. Real, C. Russell, L. Waller, D. Smith, and J. Childs study the temporal and spatial dynamics of a current rabies epidemic in North America by considering local environmental variables, genetic heterogeneity, and host specificity. In ‘‘Interaction of Rearing Environment and Reproductive Tactics on Gene Expression Profiles in Atlantic Salmon,’’ N. Aubin-Horth, B. H. Letcher, and H. A. Hofmann study the effects of rearing environment (either in a natural stream or in laboratory conditions) on